Rosa species Grandiflora

PEST

   NAME

     Two-spotted Mite, Red Spider Mite

     Tetranychus urticae

   ORDER

     Acarina

   FAMILY

     Tetranychidae

Description of the Pest

Also known as the red spider mite. Females are pale green or yellowish, depending on the host plant, and have two dark lateral markings; the mite becomes red in winter, retaining their dark markings. Nymphs are six-legged, with another pair of legs appearing as the mite matures. Males are smaller and narrower. Fully-grown adults are just visible to the naked eye. Two-spotted mites spread by crawling between nearby plants or movement of dead leaves.

Appearance and Distribution of the Pest

Found world-wide; an introduced pest in Australia. They congregate in protected places, such as under bark and at the base of trees, during winter. During spring, they become green in colour, and migrate back into the leaves. During heavy infestations, the leaves may be covered in visible webs, which they spin as they feed. Leaves may eventually wither and fall. Mites can spread via the movement of dead leaves, or in webs that have become attached to birds or large insects. They initially appear on the undersides of leaves.

Spruce Spider Mite (Oligonychus ununguis) is a tiny greenish black adult which lays eggs on twigs where they overwinter. The pale green young spiders suck the sap turning the leaves yellow to brown. Heavy infestations form webbing and the pest is found on Abies and Juniperus species.

Banana spider mite (Tetranychus lambi) is a major widespread pest of bananas.  It differs from two spotted mite by not producing copious amount of webbing.  It is highly active during the dry spring to summer period and with the onset of the wet season mite numbers are reduced.  The warm dry conditions that are created under plastic bunch covers is ideal for building up banana spider mite numbers.

Damage is normally confined to the underside of leaves appearing as rusty patches that coalesce along the leaf veins eventually turning the whole leaf brown-grey before it collapses.  Fruit is damaged, close to the bunch stalk causing the area to become dull red purple-black, which in turn becomes dry then cracks.

  Damage fruit

Control methods include careful water management during dry periods, and the reduction of dust from roadways.  Regular desuckering and leaf trimming of plants will assist with a good coverage when spraying miticides.

Life Cycle

Mites have a gradual metamorphosis, with several nymphal stages. Each female lays up to 100 eggs that hatch in 7-14 days, with several generations appearing throughout the year. Females may become inactive during cold weather.

Webbing         

Period of Activity

The Two-spotted mite is most active in hot dry conditions. Under optimum conditions, the population can double every four days. It produces large quantities of webbing for over-wintering nests. Many plants are only susceptible to this insect when cultivated under glass.

Damage Caused

Adults and nymphs lacerated the undersides of the leaves with there rasping mouth parts, although infestations on both surfaces are not uncommon. Infestations cause leaf mottling leaf fall; premature leaf loss causes loss of vigour and reduces the quality and quantity of future crops. Repeated infestations, year after year, may weaken root growth and kill herbaceous plants.

Susceptible Plants

A wide range of plants are attacked by the Red Spider Mite including annuals, fruit trees and vegetables, ornamental shrubs and trees.

Note

Many plant species are more susceptible to Red Spider Mite when they are cultivated under glass.

Other species of mite that are mentioned below have simular characteristics.

Calluna, Rose, Tropaeolum and Viola and species are infested with the Red Spider Mite (Tetranychus telarius) commonly in greenhouse situations.

Musa species are attacked by two spotted mite and banana spider mite damaging foliage and fruit.

Juglans species can be infested with up to four types of mites including red spider.

Cultural Control

Heavy rain or irrigation can reduce numbers; some plants may benefit from replanting in cooler locations. Generally, however, infested material should be completely removed and destroyed.

Preventative measures such as removing weeds or mulching around trees or shrubs or scrubbing the loose bark of susceptible trees during winter helps reduce numbers. During spring sticky bands can be wrapped around trunks close to the ground to trap the mites.

Biological Control

Natural predators include lacewings, ladybirds and thrips help keep the numbers down. Insecticide-resistant predatory mites (Typhlodromus occidenyalis) are also available commercially to control the Two-spotted Mite only on a large scale, as they require ample mites to survive.

Chemical Control

Spraying should be carried out as a last resort as many predators are killed during the operation and spraying can have the opposite effect by increasing numbers in the long term. Dimethoate will reduce numbers; however, Two-spotted mites are resistant to insecticides in some areas. Dusting with wettable sulphur may also prove effective.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Leaf Hopper (General)

     Various Leaf Hopper Species

   ORDER

     Hemiptera

   FAMILY

     Eurytomidae

Description of the Pest

Generally hopper grows up to 15mm in length, with "A"-shaped folded wings that give it a characteristic triangular cross-section. The adults often have bright coloured markings and the nymphs conjugate in colonies.   Adults can fly but will hop away immediately if disturbed and both nymphs and mature hoppers have piercing and sucking mouth parts.

The Passion Vine Hopper (Scolypopa australis) has clear triangular wings that have brown margins and black bands. The nymphs are wingless and white with tufts of hair on the end of the abdomen.

The Green Leaf Hopper (siphanta acuta) looks triangular with its steeply folded wings and can grow to 10mm long. The adults are generally a solitary feeder but the nymphs congregate on shoots.

Appearance and Distribution of the Pest

The adults and nymphs are present throughout the year in tropical to warm temperate regions and are dispersed by flying.

                 

Life Cycle

These insects have a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

Females deposit eggs in slits they make in the bark or on the leaves of the host, and several generations may appear annually on the same plant.

Egg and Nymph  

Damage Caused

Nymphs and adults are gregarious, and both stages may be found on host plants at the same time. If large numbers attack young new growth, sucking sap from leaf petioles and young stems, the host plant may become stressed. Severe infestations may weaken and eventually kill the plant with dieback and distorted leaves.

The nymphs exude a sweet secretion, which is attractive to ants that attend and protect the colony. The honeydew also causes sooty mould to occur as a secondary problem. Some species produce toxic saliva that kills the effected plant tissue; other species carry plant viruses.

Susceptible Plants

Most Eucalyptus, Acacia and Casuarina species are attacked by a variety of leafhoppers. Many other Australian native and ornamental plants are attacked.

Acer species are attacked by the leaf hopper (Alebra albostriella) which lays eggs under the bark causing minor swelling. Acer platanoides is particularly venerable.

Callistephus and Aster species are attacked by the Leaf Hopper (Macrosteles fascifrons) that generally causes little harm to the plant but transmits Yellow Disease, a viral infection.

Fern species are attacked by several types of leaf hopper, particularly the Passion Vine Hopper (Scolypopa australis). New fronds become deformed or misshapen as the insect sucks the sap causing dead patches to appear.

Parthenocissus species are attacked by the Green Leaf Hopper.

Rosa species are attacked by the Rose Leaf-hopper (Edwardsiana rosae), nymphs feed on the underside of leaves causing white blotches.

Sorbus aucuparia is attacked by the Japanese Leaf Hopper (Orientus ishidae) which causes the leaves to form a brown blotches with yellowish margins.

Cultural Control

Improving the culture of the host species may assist in maintaining vigorous growth, to minimise shock from infestations. It may be possible to remove them by hand, from young trees, using a small butterfly net if you are lucky.

Biological Control

Controlled by natural predation and the Green Leaf Hopper causes little harm and control is unnecessary.

Chemical Control

Under normal circumstances, it is impractical and unnecessary to treat mature trees however, hoppers on young plants may be treated with a contact insecticide. Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     San Jose Scale

     Quadraspidiotus perniciosus

   ORDER

     Hemiptera

   FAMILY

     Diaspididae

Description of the Pest

An armoured scale (sometimes known as hard scale). Adult females are yellow, soft bodies and the size of a pinhead, with a 2mm grey-brown, conical covering scale; males are smaller, ovoid with the raised section towards one end of the scale. This is a major pest in some areas and is difficult to detect, as they are small, resemble the twigs that they are on.

Appearance and Distribution of the Pest

Known throughout the world. It is quarantined in South Australia, where this scale is not seen.

Life Cycle

This insect has a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

There is a gradual metamorphosis, with several generations appearing in each year; the life cycle is about six weeks. Nymphs are six-legged and mobile, until they settle and begin to feed on the sap. Adult males emerge from their scale coverings as minute winged insects.

Period of Activity

Most activity occurs during the warmer months.

Damage Caused

All above-ground parts of the plant may be attacked. Scales may overlap, covering the bark of the plant; feeding scales inject a toxic substance, which may kill twigs and limbs in heavy infestations. Because it is a proclaimed pest, control is required by law: scale must be removed from all infested plants in an orchard, and export of infested fruit is prohibited.

Susceptible Plants

Deciduous fruit trees, especially apples, pears, stonefruit. Ornamental trees and shrubs such as Paeonia and Cotoneasters, Thuja species are also attacked.

Cultural Control

Sticky traps may be used to control crawlers; traps should be changed weekly. Dead or damaged parts of the plant should be removed and destroyed including fallen fruit. Small infestations may be removed by hand or squashed on the stems. Healthy plants are less susceptible to attack, so maintain vigour of the plant and avoid using high-nitrogen fertiliser that produces excessive soft young growth.

When pruning susceptible plants paint the cuts with antifungal sealant paint as scale insects are attracted to the sweet smell of the sap. This will reduce the infection rate of the plant.

Biological Control

Native ladybeetles, other predatory beetles and scale-eating caterpillars do not reduce numbers significantly.

Chemical Control

White oil and other oil sprays smother the insects, but do not destroy the eggs. Methidathion may be successfully used commercially.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Rose Scale

     Aulacaspis rosae

   ORDER

     Hemiptera

   FAMILY

     Diaspididae

Description of the Pest

Females are flat, rounded white scales, up to 3mm across; males are smaller and narrower. Nymphs (or "crawlers") are tiny and red.

                  Female Scale

Appearance and Distribution of the Pest

This scale is found throughout the world.

Life Cycle

This insect has a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

Females lay up to 40 eggs; two generations may be produced each year. Females live for up to one year, and several overlapping generations may appear on one plant. Stems may be completely covered by scale.

Male Scale

Period of Activity

Active throughout the year in warmer regions.

Damage Caused

Stems become encased in heavy infestations, causing loss of vigour and stunted growth.

Susceptible Plants

Typically found in encrustations on the stems and branches of roses, blackberries and raspberries.

Cultural Control

Remove and destroy heavily infested plants. Spray with white oil or soapy solution. Infestations on thick stems may be brushed off.

Biological Control

Predatory caterpillars may reduce numbers.

Chemical Control

Contact pesticides such as maldison are suitable in domestic infestations; in commercial settings, scale may be kept under control with applications of methidathion.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Cottonycushion Scale

     Icerya purchasi

   ORDER

     Hemiptera

   FAMILY

     Margarodidae

Description of the Pest

This pest is also known as Ribbed Scale or Bark-louse. The small soft bodied female is oval shaped, reddish-brown, and produces an extended fluted egg sack up to 10mm long that is covered with white, waxy threads. The crawlers are red with dark legs and the adult males are winged. The nymphs infest the ribs and veins of leaves, sucking the sap. Adults and nymphs suck sap with piercing and sucking mouth-parts and ants are attracted to the honeydew produced by feeding nymphs.

       Image by B. Sonsie

Appearance and Distribution of the Pest

This insect has a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

Adults appear during the warmer months and infest twigs branches and are found on the trunks of some trees.  Ants will usually be present as feeding nymphs produce honeydew, as will the Verdalia ladybeetle, (Rodolia cardinalis), which feeds on the nymphs.

This Australian native insect has been introduced to many countries such as the USA, India, Egypt and South Africa and was only brought under control by the introduction of the Verdalia ladybeetle.

Period of Activity

There are usually two hatches each year, in early spring and late summer.

Susceptible Plants

There are many plants that are attacked by this insect including Australian native species such as Acacia, Eucalyptus, Pittosporum, Hakea and Grevilleas.

Ornamental trees and shrubs are also attacked including fruit trees and citrus, Liquidambar, Salix, Nerium, Magnolia, and Rosa species.

Palm such as Archontophoenix and Howea species are also attacked particularly when grown as an indoor or glasshouse specimen.

Damage Caused

Heavy infestations may cause die-back, particularly where natural predators are absent (eg in glass-houses). The excretion of honeydew promotes sooty mold that restricts the leaves capability to photosynthesize.

Cultural Control

Dead or damaged parts of the plant should be removed and destroyed including fallen fruit. Small infestations may be removed by hand or squashed on the stems. Healthy plants are less susceptible to attack, so maintain vigour of the plant and avoid using high-nitrogen fertiliser that produces excessive soft young growth.

When pruning susceptible plants paint the cuts with antifungal sealant paint as scale insects are attracted to the sweet smell of the sap. This will reduce the infection rate of the plant.

Biological Control

Natural predators such as parasitic wasps may reduce numbers of active nymphs; parasitic wasps are bred commercially in some areas for this purpose and the main natural predator is the Verdalia ladybeetle, (Rodolia cardinalis). It should be noted, however, that wasps would avoid dusty conditions.

Other predators that assist in control are assassin bugs, lacewings, hover flies and scale eating caterpillars. A variety of birds also attack scales.

Chemical Control

Normally not necessary.

PEST

   NAME

     Budworms

     Helicoverpa species

   ORDER

     Lepidoptera

   FAMILY

     Noctuidae

Description of the Pest

Mature larvae are caterpillars up to 45 mm long; colour varies from yellowish-green to reddish-brown, most with stripes or darker body markings. Female moths have a wingspan up to 40 mm across, are reddish brown in colour; hindwings are pale at the base and dark along the edges.

Moths of Heliothis are very similar to that Helicoverpa armigera (Corn earworm).

Helicoverpa have a spot which is kidney shaped in the centre of the forewing,

The Adults of all species are attracted to lights at night.

                 

The larvae are smooth and vary in colour but have light coloured strips

Life Cycle

This insect has a Holometabolous life cycle, i.e. it has a larval and a pupal stage.

Females lay up to 1000 tiny white eggs, deposited singly, on the young growth of host plants.

Larvae pupate in the topsoil, after feeding for 2-3 weeks; the emergence of adults is triggered by appropriate moisture & temperature conditions during Spring. Long periods of cold and drought can delay the emergence of the adult moths for up to 5 months.

There are two main periods of infestation early summer and autumn.

Distribution of the Pest

Helicoverpa species (Heliothis species) are found throughout Australia.

Larvae have prominent prolegs

Period of Activity

Most active in Spring and Summer, after good rainfall and vigorous plant growth.

Damage Caused

Larvae attack chew on new growth, fruit, seed and flower buds. Fruit and flowers are damaged and yield is reduced. Entry holes in fruit enlarge and become more obvious as the caterpillar matures.

Bud worms which feed inside the flower buds can cause the buds to brown and not open.

Damage to a flower bud

Susceptible Plants

Attacks a wide range of fruiting and ornamentals plants, such as gardenias, carnations, roses, calendula, hollyhocks, snapdragons, etc. This is a major pest of commercially grown tomatoes, beans,

sweet corn, cotton, sorghum and peas.

Pseudotsuga menziesii, Picea, Pinus, Pseudolarix and Tsuga species are attacked by the Spruce Budworm (Choristoneura fumiferana). Symptoms include the new opening buds and needles are eaten by the dark red caterpillar that has a yellow stripe along its side. It is a serious pest to ornamental and forest trees and control is difficult.

Control

Cultural Control

It is difficult to control bud-worms once they enter the fruit or buds so it important to apply clay and pepper sprays or pyrethrum, while the young lava are feeding on the leaves.  Caterpillars may be removed by hand or infested flowers and fruit removed from the plant.

Biological Control

Genetically modified crops have been developed for cotton.

A virus NPV may be commercially available for cotton growers to control Helicoverpa armigera and H punctigera

Helicoverpa armigera & Helicoverpa punctigera), are parasitised by many different insects, including Chaetophthalmus dorsalis flies from the Tachinidae family.

Egg parasites include Trichogramma & Telenomus wasps

Larval parasites include         Micrropilitis demolitor, Netelia producta and Trachnid flies

Larval pupa parasites include Heteropelma scaposum and Lissopimpla excelsa

Pupal parasites include Ichneumon promissorius

Chemical Control

Control needs to occur before the larvae enter the fruit or flowers.

Note

It is your responsibility by law to read & follow the directions on the label of any pesticide

Monitoring

Shake plants twice a week on to a stiff white cardboard, once they start flowering.

Other Common Names; includes

Native Budworm (Helicoverpa punctigera) Tomato grub, Cotton bollworm, Corn ear worm, Tobacco budworm

Amendments by B. Sonsie Dip Hort Sc Burnley

PEST

   NAME

     Thrips (General)

     Various Thrip Species

   ORDER

     Thysanoptera

Description of the Pest

There are many species of thrips that attack living and dead plant material. The winged adults are black, yellow, white or brown with slender bodies and up to 2mm long. The folded fringed wings appear as silvery stripes and the smaller nymphs are difficult to see, but are wingless simular to the adults. Both adults and the first two nymphal stages have rasping and sucking mouthparts.

Thrip species

Boree Gall (Kladothrips species) adults are gall producing thrips that form smooth bubble-like or irregular spiny growths on the leaves. These galls can contain up to 1000 insects that also reproduce inside, and are trapped until the gall dries or splits open. Commonly found in inland areas attacking the phyllodes of Acacia species.

Glasshouse Thrips (Heliothrips haemorrhoidalis) is a slender up to 15mm long with small fringed wings. The adult lays eggs on the underside of leaves where the nymphs emerge as miniature adults but wingless. Then feed on the soft leaves leaving a silvery mottled appearance.

Appearance and Distribution of the Pest

Thrips are found from tropical to temperate regions preferring a cool mild winter followed by a dry sunny spring that produces abundant flowers and new foliage. It is dispersed by flying and can be carries great distances on the wind.

Life Cycle

These insects have a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

The female adult lays her eggs using an oviposit in a slit on flower stems or occasionally leaves. The eggs develop into four nymphal stages. The first two stages occur on the plant and the last two in the surrounding soil or in leaf litter, emerging as adults and flying to reinfect the plant. It takes ten to thirty days to develop from egg to adult depending on the temperature and rainfall. Under opium conditions thrips are produced in plague proportions.

Period of Activity

Thrips are most active during warm dry, calm weather, but dislike the soil to be too dry or wet.

Damage Caused

Thrips congregate inside the flowers damaging the epidermal layer, allowing sap to leak out. This causes the flower petals to become brownish and curl along the margins. They also attack the upper surface of leaves causing a silvery discolouration as they suck the sap. The effect is a reduction in fruit and seed production on the host plant.

Susceptible Plants

Generally many plants species are attacked by thrips including buds, petals and leaves that are soft are at most risk, such as Alyogyne , Baeckea, Hibbertia, Hibiscus and Leptospermum species. There is also a wide range of ornamentals suseptable to attack including apples, pears, citrus, stonefruit, grapes and strawberries.

Buddleja species may be attacked by the thrip (Hercinothrips femoralis).

Cordyline, Agave, Dracaena and Howea species, Ficus elastica are attacked by the Dracaena Thrips (Parthenothrips dracaenae) which feed of the leaves.

Knightia excelsa is attacked by thrips by feeding on the chlorophyll in the leaf causing significant paling of the leaves. Stresses plants are more susceptible and plants rarely die from attack.

Peperomia, Cissus, Tropaeolum and Passiflora species and some fern species are attacked by Glasshouse Thrips which can cause heavy damage in inclosed areas such as a glasshouse.

Watsonia species are attacked by the Gladiolus Thrips (Taeniothrips simplex).

Cultural Control

There is no satisfactory cultural control. Small infestations may be ignored or the plant may be hosed to reduce the numbers. Removal of surrounding leaf litter, weeds and cultivating the soil can also reduce the numbers and disturb the life cycle. Care should be taken not to remove flowering weeds under trees that are in bloom as the thrips may migrate on to the tree, alternatively flowering annuals can be planted under trees to attract the thrips away.

Biological Control

No effective natural control though birds; wasp and other predators eat thrips. Weather conditions such as heavy rain help reduces numbers.

Chemical Control

Thrips can be sprayed with Dimethoate or Maldison at least twice every ten days to kill newly hatched nymphs, but may have a detrimental effect on other insects such as bees.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Capsid bugs

     Lygocoris species

   ORDER

     Hemiptera

   FAMILY

     Miridae

Description of the Pest

Capsid bugs have piercing and sucking mouthparts. They have two pairs of wings, with the forewings thicker at the base and covering the hindwings at rest.

Adult bugs are up to 6 - 12 mm long the wings are coloured two thirds from the body becoming transparent at the end when flatly folded the transparent areas form an obvious diamond-shape. While feeding they secrete a toxic fluid that kills the surrounding cells. They look like large Aphids

Adult      Adult with piercing and sucking mouth parts

Life Cycle

These insects have a Hemimetabolous life cycle i.e. the nymphs resemble the adults.

Distribution of the Pest

Europe and the USA

Life Cycle

These insects have a Hemimetabolous life cycle, i.e. When the nymphs resemble the adults.

Period of Activity

The bugs are most active from late spring to late summer.

Damage Caused

After being attacked the young leaves towards the shoot tips expand and small holes with brown margins are formed. Flowers that are affected may fail to open or open unevenly with damaged petals.

The apple capsid bug (Plesiocoris rugicollis) attacks developing fruit forming blemishes on the skin but not affect the quality of the fruit.

Susceptible Plants

There are many ornamental plants that are attacked; these include Fuchsia, Chrysanthemum, Dahlia, Magnolia, Rosa, Hydrangea and Salvia species. Fruit and vegetables are also susceptible to attack.

Cultural Control

Difficult to control, infected buds may be removed during early spring.

Chemical Control

Infected buds may be sprayed in early spring

Note

It is your responsibility by law to read & follow the directions on the label of any pesticide.

Amendments by B. Sonsie Dip Hort Sc Burnley

PEST

   NAME

     Aphids

     Various Aphid Species

   ORDER

     Hemiptera

   FAMILY

     Aphididae

Description of the Pest

The common name varies and aphids may be referred to as black fly, greenfly, ant cows or plant lice.

These small insects have soft globular body that is from 1mm to 8mm long and vary in colour from green, yellow, black and pink, with the winged forms being elongated. Both adult and nymphs, have piercing and sucking mouthparts.

Aphids are found on buds, flowers, or leaves and stems, preferring soft new growth. On older leaves the aphids are found in protected positions, such as under the leaf. Certain species of aphids form galls as they suck sap and may be found on the roots of the plant. (E.g. Woolly aphids and Black peach aphids)

Most aphids possess a pair of characteristic tubular projections, known as cornicles; these secrete a pheromone and a waxy fluid, which is thought to protect them from some of their predacious enemies.

White exoskeletons, honey dew and sooty mould indicate the presence of Aphids

Balsam Twig Aphid (Mindarus abietinus) is greenish and covered in a white wax and is normally found on the young shoots of conifers bending and killing the needles. It is found on Abies and Picea species.

Aphid and their exoskeletons    on underside of a leaf

Black Citrus Aphid (Toxoptera aurantii) has a soft plump green body and the black coloured adults may or may not be winged. They feed in groups, curling leaves and producing honeydew attracting sooty mould.

Green Peach Aphid (Myzus persicae) is a soft plump green insect up to 0.2mm long and may be wingless. The nymphs are yellowish green and are responsible for spreading viruses in Dianthus species.

Spruce Gall Aphid (Chermes abietis) form cone shaped galls up to 12mm long resulting from the feeding. The wingless female adult lays eggs on the stems and the immature females overwinter on bud scales. Large infestation will weaken trees such as Picea abies and Pseudotsuga menziesii.

Tulip Bulb Aphid (Anuraphis tulipae) is small, waxy grey coloured and infests the underside of the bulb scales or rhizomes. They occur in the ground or on above ground parts and during storage.

Life Cycle

These insects have a Hemimetabolous life cycle, i.e. The nymphs resemble the adults.

During spring all eggs produced hatch as female nymphs. Adult Aphids are capable reproducing without fertilisation.  The males are only produced in some species as the weather cools down, and the day length shortens.

Aphids are capable of giving birth to living young and large populations build up quickly during summer. Over crowding causes the aphids to become smaller, less fertile and produce more winged forms that can migrate to other host plants.

There are many different types of aphids and the life cycle varies from warm to cold climates.

Typical life cycles

Distribution of the Pest

World wide

Period of Activity

In warm climates they are seen throughout the year, but aphids dislike hot dry or cold conditions and heavy rain will decrease the population. In cold areas aphid eggs are laid around a bud base or other protected areas of the plant during autumn and emerge as nymphs during spring, feeding on the new growth.

Numbers build up quickly in the warmer months of the year. Some species feed during winter on Sow thistles.

Susceptible Plants

There is a wide range of plants attacked, from roses to vegetables, shrubs and trees. Certain aphids attack a specific genus while others have a wide range of host plants. Many are capable of transmitting plant virus diseases.

Adults and nymphs feeding    A colony of aphids

Acer species are attacked by several aphids including the Norway Maple Aphid (Periphyllus lyropictus) which is a greenish with brown markings and secret honeydew, preferring Acer platanoides. Other aphids include (Drepanaphis acerifolia) and (Periphyllus aceris) which are commonly found on the underside of leaves.

Acer species are also attacked by the Woolly Maple Aphid (Phenacoccus acericola) which covers the undersides of the leaves with a cotton-like mass

Alnus species are infested with the Alder Blight Aphid (Prociphilus tessellates) which is blue-black adult that forms woolly masses on the down-turned leaves. The nymphs overwinter in bark crevices.

Aquilegia species are attacked by several aphids including (Pergandeidia trirhoda) which is a small, flat cream coloured insect that is found on young branches and the underside of leaves.

Betula species may be attacked by the European Birch Aphid (Euceraphis betulae) which is small and yellowish or the Common Birch Aphid (Calaphis betulaecolens) which is large and green producing ample honeydew for sooty mold to grow on.

Callistephus species may be attacked by the Corn Root Aphid (Anuraphis maidi-radicis) causing the plant to become stunted, the leaves wilt and turn yellow. The aphids feed on the roots producing honeydew and are dispersed to other host by ants. It is also attacked by the Potato Aphid (Macrosiphum solanifolii).

Carya species are attacked by Gall Aphids (Phylloxera caryaecaulis) which is found on the leaves, twigs and stems forming galls and turning them black.

Chaenomeles and Gladiolus species, new growth and leaves become infested with the aphid (Aphis Gossypii)

Cupressus macrocarpa may become infested with the Cypress Aphid (Siphonartrophia cupressi).

Cyclamen species are attacked by the aphid (Myzus circumflexus) and (Aphis gossypii) which can infest healthy plants.

Dendranthema, Dianthus  and Crocus species are attacked by several types of aphid including the Green Peach Aphid (Myzus persicae) and the Chrysanthemum Aphid (Macrosiphoniella sanborni).

Hibiscus species are attacked by the aphids (Aphis craccivora)  and (Aphis gossypii), both congregate towards the branch tips and may cause leaf curl. Normally only seen in sub-tropical climates.

Aphids on a stem    Mandevilla species

Larix species is attacked by the Woolly Larch Aphid (Adelges strobilobius). The winged adults deposit eggs at the base of the needles during spring and white woolly areas appear attached to the needles where the adult aphids feed. The young aphids overwinter in the crevices of the bark.

Mandevilla species is attacked by aphids that congregate towards the branch tips and may cause leaf curl.

Pinus species is attacked by several species of aphid including Pine Bark Aphid (Pineus strobi), Pine leaf Aphid (Pineus pinifoliae) and the White Pine Aphid (Cinara strobi).

Primula species are attacked by four species of aphid including foxglove, and green peach aphid.

Rudbeckia, Delphinium, Chrysanthemum and Helianthus species are attacked by a bright red aphid (Macrosiphum rudbeckiae).

Sorbus aucuparia is affected by the Rosy Apple and Woolly Apple aphid which attacked the foliage and young shoots.

Spiraea species are attacked by the Aphid (Aphis spiraecola) which feeds on the young shoots and flowers.

Tropaeolum species are attacked by the Black Bean Aphid (Aphis fabae), which is found in large numbers on the underside of the leaves, turning them yellow and causing them to wilt then die.

Tulipa, Iris, Freesia, Gladiolus and Zephyranthes species are infested with the Tulip Bulb Aphid.

Ulmus species are infected by two types the Woolly Apple Aphid (Eriosoma lanigerum), which curls and kills young terminal leaves and the Elm Leaf-Curl Aphid (Eriosoma ulmi) which occasionally attacks the trees.

Viburnum species are attacked by the Snowball Aphid (Anuraphis viburnicola). This aphid congregates at the end of the branches causing the leaves to curl and become deformed under which they hide.

Aphids on Quercus robur

Damage Caused

Buds that have been attacked may not open, leaves and twigs become twisted or distorted and wilt. The aphids also produce honeydew, which is sticky and attracts sooty mould (fungus). This fungus forms a thick layer over the leaf, fruit or stems reducing the plants photosynthesis capability. The sooty mould spoils the plants appearance and its fruit, as does the insects white exoskeletons.

Control

Cultural Control

Aphids may be removed from a plant by hosing them off with water (limited success) or applying soapy water to aphids.. Another organic sprays can be efficient in controlling aphids. Aphids  may also be removed physically by hand for small colonies on spine less plants. Species that live under ground are difficult to control but cultivation of the surrounding soil may help in controlling the infestation. (limited mainly to annual or commercial crops)

Reflective mulch around the plants also reduces numbers by repelling the insect this material is available commercially. (Reflective mulches are mainly used in market gardens for avoiding the Green peach Aphids) Resistant rootstocks are available to avoid some root feeding aphid of commercial plants, e.g. Vines and fruit trees

Biological control

Aphids are attacked by several insects includes parasitic wasps or predators such as ladybirds/ lady beetles, hover flies, lacewings, spiders.

   Parasitised aphids

Chemical Control

Aphids may be controlled by spraying with a contact or systemic insecticide. The type of application used will depend on the plant is being attacked.

Aphids can be suffocated and therefore controlled with the use of e.g. White oil, Pest oil, Soapy water from soap such as Lux Flakes ®

Note

It is your responsibility by law to read & follow the directions on the label of any pesticide

Monitoring

Aphid are attracted by yellow colour and traps such as boards painted yellow and covered in glue or sticky substance will attract and trap the insects.  There is also a commercially sticky yellow tape that can be attached to susceptible plants

Amendments by B. Sonsie Dip Hort Sc Burnley

PEST

   NAME

     Fuller's Rose Weevil

     Various Rose Weevil  

Species

   ORDER

     Coleoptera

Description of the Pest

The Fuller's Rose Weevil (Asynychus cervinus) is greyish-brown and grows to 7mm long and is found in Australia. The female adult has faint white marks on its sides and feeds on leaf margins and flower buds. It lays its eggs under loose bark or in curled dead leaves that have fallen to the ground. The light grey lava is up to 6mm long burrow down feeding on the roots, where they overwinter.

The Fuller's Rose Weevil (Pantomorus godmani) female adult is greyish-brown, up to 8mm long with diagonal white stripes across its wing covers and feeds on leaves at night. It is found in northern and southern USA. The lava feed on the roots and overwinters under ground.

Distribution of the Pest

Fuller's Rose Weevil's are found throughout the world and are distributed by walking to a new host or are transported on infested plants.

Life Cycle

These insects have a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

The adult female can live up to three months during which it can lay up to ten groups of thirty eggs and the lava, can remain under ground for up to nine months before emerging as adults.

Period of Activity

The adult is most active from summer to autumn.

Damage Caused

Generally the adults chew leaves, preferring new foliage or flower buds and on mass can cause sever damage to the host. The roots are attacked by the lava and may cause yellowing of the foliage and small plants such as Lycopersicon species may be killed.

Susceptible Plants

There are many plants that are attacked by these pests, particularly broad leafed types.

Camellia, Citrus, Dahlia, Gardenia, Passiflora, Prunus, Rosa and Rubus species are susceptible to the Fuller's Rose Weevil (Asynychus cervinus).

Acacia, Begonia,  Camellia, Canna, Chrysanthemum, Cissus, Citrus, Dianthus, Diospyros, Dracaena,  Fuchsia, Gardenia, Hibiscus, Lilium, Pelargonium, Penstimon, Plumbago, Prunus persica, Quercus, Rhododendron,  Rosa and Vinca, species.

All are susceptible to attack by the Fuller's Rose Weevil (Pantomorus godmani).

Cultural Control

Small infestations may be removed by hand at the adult stage and fallen leaves or debris should be removed from around the base of the plant. Sticky traps at the base of the plant may inhibit the adult climbing the plant.

Chemical Control

Plants may be sprayed with Carbaryl when the adults are first seen.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Leafcutting Bee

     Megachile species

   ORDER

     Hymenoptera

   FAMILY

     Megachilidae

Description of the Pest

Adults grow to 15mm in length; they resemble honey bees in size and shape, but are black in colour, with lines of pale hair on their abdomens. They have modified chewing mouthparts. They are solitary, cause little damage, and are often important pollinators.

                  Hair on abdomen

Appearance and Distribution of the Pest

Leafcutter bees occur in Australia, Europe and North America.

Life Cycle

These insects have a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

Period of Activity

Most active during the warmer months.

Damage Caused

As their name suggests, leafcutter bees cut oval or circular pieces (up to 10mm across) from the margins of the leaves of susceptible plants, which they use to line their nests, which they construct in natural cavities.

Susceptible Plants

A wide range of ornamentals are susceptible, particularly Rosa, Syringa (lilacs), Camellia, Wisteria, and Prunus species.

Cultural Control

The insects may be swatted when seen but, as they cause little serious damage, this is unnecessary.

Biological Control

There is no effective (or necessary) biological control.

Chemical Control

Not usually indicated.

PEST

   NAME

     Nectar Scarabs

     Phyllotocus species

   ORDER

     Coleoptera

   FAMILY

     Scarabaeidae

Description of the Pest

Adult beetles have a characteristic scarab shape, up to 6mm in length, with exaggerated hind legs. The head and thorax is dark brown; the wings have orange-brown longitudinal striations. Larvae appear as small white curl grubs. Both larvae and adults have chewing mouth parts.

Flower Scarab Beetles (Protaetia apecies). Thiese active beetles are stout and broad up to 20mm long. The colouring is normally brown with some having small pale markings on the wing covers. It is commonly found feeding on Myrtaceae or Proteaceae flowers (pollen) or shoots of Acacia species. It is a solitary feeder and may cause dieback of the host.

Appearance and Distribution of the Pest

Nectar scarabs are Australian natives but are rarely found in the Northern Territory. They are distributed by flying to a new host plant.

Life Cycle

These insects have a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

It has a complete metamorphosis producing one generation every one to three years, depending on the species. The eggs are laid during spring normally near the surface of the soil and the lava burrow into the soil. The lava overwinters deep in the soil and pupates during spring.

Period of Activity

Most active during the warmer months, when plants are flowering.

Damage Caused

Larvae feed on decaying vegetable matter and cause little damage. Adults swarm on host plants in large numbers, feeding on pollen and nectar; when swarming they may also feed on the flower parts.

Susceptible Plants

Many plants are attacked by this insect including Acacia, Eucalyptus, Melaleuca and Callistemon species. Ornamentals such as Rosa and Dahlias species are also attacked.

Cultural Control

Small infestations may be removed by hand but certain species such as the Flower Scarab Beetle drop to the ground and pretend to be dead. This is an opportunity to collect them on a piece of plastic if it is spread around the plant.

Biological Control

No known controls.

Chemical Control

Contact insecticides such as Carbaryl are effective, but not normally necessary.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Western Flower Thrips

     Frankliniella occidentalis

   ORDER

     Thysanoptera

   FAMILY

     Thripidae

Description of the Pest

Adults are tiny (1mm) long cigar-shaped insects with banded abdomens, and two pairs of feathery wings. Nymphs have yellow bodies. Adults and nymphs have rasping and sucking mouth parts.

Appearance and Distribution of the Pest

Found throughout Australia.

Life Cycle

This insect has a Hemimetabolous life cycle, ie. When the immature nymphs resemble the adults.

Later (non-feeding) nymphal stages occur in leaf litter or surrounding soil. Adults mature in a fortnight under ideal conditions; they may survive for six weeks and produce up to 300 eggs over this period. Many generations appear each year.

Period of Activity

Most active during warmer dry months

Damage Caused

Adults and nymphs feed on plant tissue of flowers, shoots and fruit. Flowers develop silvery discoloration; shoots and fruit may become deformed. Eggs are also laid in the plant tissue, causing further physical damage and making the plant susceptible to wilt.

Susceptible Plants

A wide range of flowering and fruiting plants, both native and exotic, including Dendranthema, Gerbera, Gypsophila, Rosa, Fragaria, Lactuca, Lycopersicon, Cucumis and Vicia species are attacked.

Cultural Control

No effective control.

Biological Control

No effective control.

Chemical Control

Wester flower thrips are resistant to many insecticides and only the adult and lava stage is susceptible to insecticides such as Omethoate or Maldison. Consult your agricultural authority for current advice.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Painted Apple Moth

     Teia anartoides

   ORDER

     Lepidoptera

   FAMILY

     Lymantriidae

Description of the Pest

Adult males are 25mm long and have a 25mm wingspan, with brown forewings and yellow hindwings with black edges. Females are also 25mm long, but wingless. Larvae are furry brown caterpillars, up to 30mm long, with four prominent tufts of reddish brown hair behind the head, and two horn-like tufts of black hair projecting forward. The caterpillar's hair may cause skin irritation.

                  Wingless Female

Appearance and Distribution of the Pest

An Australian native, most commonly found in temperate and subtropical regions. Originally known as the painted wattle moth, feeding exclusively on acacias, it has adapted to feed on apples and other species.

Life Cycle

This insect has a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

Larvae pupate in loosely woven cocoons; eggs are laid on the empty cocoons.

Period of Activity

May be active all year, particularly during the cooler months.

Damage Caused

Larvae may skeletonise leaves; small plants may be defoliated. Because females are flightless, infestations are localised.

Susceptible Plants

A wide range of plants are affected, including apples, Acacias, Melaleucas, Grevilleas, and many exotics. Some fern species are also attacked.

Rosa species leaves are attacked by larva.

Cultural Control

Remove small infestations of larvae and cocoons by hand.

Biological Control

None known.

Chemical Control

Maldison, Carbaryl or other contact pesticides are effective; a wetting agent is necessary to penetrate the larval hair.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Light Brown Apple Moth

     Epiphyas postvittana

   ORDER

     Lepidoptera

   FAMILY

     Tortricidae

Description of the Pest

Adults are small, bell-shaped light brown moths; females grow up to 20mm long and are pale brown; males are smaller with orange-brown coloured patterns. Larvae are up to 20mm long with slender yellowish-green, segmented bodies and brown heads. Larvae have chewing mouth parts. When brushed from the plants, they remain suspended from silk threads.

Appearance and Distribution of the Pest

Lightbrown apple moths occur throughout Australia, and have been introduced into Europe.

Life Cycle

These insects have a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

Life cycle takes 2-3 months, with up to three generations appearing each year.

Period of Activity

Most active when fruit are maturing.

Damage Caused

Larvae spin silk threads, and may bind young leaves together to form a shelter to feed from. Young larvae feed on the leaves and the mature larvae attack fruit.

Susceptible Plants

A wide range of ornamentals that are susceptible to attack including; Olearia and Rosa species, apples, grapes, citrus, persimmons and stonefruit. Immature grapes are particularly susceptible to damage by the larvae.

Fern species are also attacked joining pinnae together for shelter in which they feed or leave the nest at night to feed on the surrounding fronds. They are most active during the summer months.

Cultural Control

Small numbers may be removed by hand; fruit may be covered with fine netting to prevent infestation.

Biological Control

Natural predators and parasites.

Chemical Control

Carbaryl is effective.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

PEST

   NAME

     Japanese Beetle

     Popillia japonica

   ORDER

     Coleoptera

Description of the Pest

The adult beetle has an iridescent bluish-green body with streaked grey, wing cases and is up to 12mm long. The eggs are laid in lawn or grassy areas where the small larva feed. Both adult and larva have chewing mouth parts. The insect originated in Japan and was introduced into eastern USA and southern Canada.

This insect has a Holometabolous life cycle, ie. When metamorphosis is observed during the pupal stage.

Image by Ohio State University

Period of Activity

The adult is active and the eggs are laid from summer to autumn although the female adult normally lays its eggs in the first seven to ten days of its life.

Life Cycle

The tiny white eggs are up to 1.5mm long and are deposited on the soil where they can absorb moisture. After hatching the whitish larvae are a typical curl grub and identified by a serious of bristles in a 'V' shape on its raster.  There are three larva stages with the mature larvae growing to 32mm long, then pupate in the soil. The pupa is cream at first becoming red-brown and growing to 14mm long. Adults are oval shape, metallic green 10mm long by 7mm wide with brownish wing covers and five tufts of whitish hairs on either side of the abdomen.

Adult beetles emerge in early summer and find a suitable host plant to feed on, and then release an odour that attracts other emerging beetles to that plant. The females attract the males by emitting a pheromone and matting can occur on the host plant or on the ground. Fertilised females burrow into the soil up to 100mm to deposit up to five eggs then returning to the host plant and mate again. During the summer period the female deposits up to 60 eggs and under hot conditions the eggs can hatch within nine days. Under cooler conditions it can take up to thirty days for the eggs to hatch. Emerging larvae feed on the roots of the host plant.

Damage Caused

The adults skeletonize leaves and chew on buds or flowers, sometimes completely defoliating the host plant. The skeletonised leaves soon wither and die. Turf grass becomes spongy under foot as a result of tunnelling and the grass has a withered appearance in irregular patches that will not respond to watering. On inspection by lifting the turf numerous larvae can be found feeding on the roots.  

Susceptible Plants

There are many broad leafed plant species that are attacked including fruit, vegetables and ornamental plants. Roses are badly affected and may have up to 50 adults on a single bloom.

The larvae attack the roots of Turf Grass such as Poa pratensis (Kentucky Bluegrass), Lolium perenne (Perennial Ryegrass), Festuca arundinacea (Tall Fescue) and Agrostis palustris (Bent).

Many trees are particularly susceptible to attack and should not be planted around turfed areas such as golf courses. These include; Acer palmatum (Japanese Maple), Acer platanoides (Norway Maple), Quercus palustris (Pin Oak), Aesculus species (Horse Chestnut), Hibiscus syriacus (Rose of Sharon), Platanus occidentalis (American Sycamore), Prunus cerasifera (Cherry Plum), Prunus x blireana (Blireana Plum), Prunus campanulate (Taiwan Cherry), Prunus x yedoensis (Tokyo Cherry), Rosa species, (Rose), Salix species (Willow), Tilia species (Linden) Ulmus species (Elms) and Parthenocissus quinquefolia (Virginia Creeper).

Vitis, Alcea, Zinnia, Hibiscus and Dahlia species are also attacked.

Cultural Control

It is difficult to control infestations of Japanese Beetles, but certain measures such as keeping soil dry during the first larval stage or avoid planting trees that are susceptible to beetle attack around lawn areas will help. Small infestations may be removed by hand during the early morning and small crops may be covered in netting for protection.

Biological Control

There is no effective natural control, but certain species of parasitic wasps help control. Soils may be infected by Bacterial Milk Disease which after a couple of years can be efficient in controlling larvae, but infected areas should not be sprayed during this period as this may kill off the bacterium.

Chemical Control

Smaller plants may be sprayed with a contact insecticide when the insect is first seen or turf areas can be sprayed with a systemic chemical.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

Note: Plants affected by this pest are the Rabbit Resistant plants not the susceptible plants.

 

PEST

   NAME

     Rabbits

     Oryctolagus cuniculus & Sylvilagus species

   ORDER

     Lagomorpha

   FAMILY

     Leporidae

Description of the Pest

There are a eight different genera in the family classified as rabbits and include the European Rabbit (Oryctolagus cuniculus) which has infested Australia and the Cottontail rabbit  (Sylvilagus spp.) which consists of 13-species with 9-species found in North America.

Generally rabbits have an egg-shaped body that can range in size from 200 mm to 500 mm long and weigh up to 2 kg.  They have long ears that are adapted for detecting predators and powerful large hind legs allowing them to move fast.  The body is covered in buffed, long soft fur that is brown or grey and the mouth has two sets of incisor teeth which are located one behind the other.

The cottontail rabbit grows up to 450 mm (18 in) tall and weighs 1.36 kg (3 lbs).

Appearance and Distribution of the Pest

Generally rabbits live in a variety of habitats including meadows, woodlands, forests, grasslands or deserts and wetlands living in groups with some underground in borrowers.  The European Rabbit has been introduced to many parts of the world and in 1859 Thomas Austin brought 24 breeding pairs to Australia which subsequently escaped and quickly bred throughout Victoria and New South Wales and  by the 1900's the rabbits had reached the Northern Territory and Western Australia.

Life Cycle

The life span varies with each species. Cottontails for example can live for one year to a maximum of three years in the wild but in captivity they can last for eight years, during which time they can raise between 2-6 litters per year and produce up to 18 kittens during the breeding season. In the cooler northern parts of North America the size and number of litters are generally smaller only 2-3  but in southern regions such as Mexico or Australia, European rabbits can produce 5-6 litters per year, normally commencing during spring time and continuing throughout the year. Each litter can consist of 2-8 or more kittens. Under ideal seasonal conditions a mature doe (female) can mate again several hours after giving birth and has a gestation period from 28-30 days.  

Period of Activity

Generally rabbits eat throughout the year but in cooler countries such as North America they are more active during the spring to summer period but in warmer climates such as Australia rabbits can cause significant damage throughout the year.

Damage Caused

in Australia the effects of rabbits on the landscape has been a devastating resulting in the loss of an unknown number of plant species and a ring barking of young trees in orchards or forests.  Major erosion problems have also resulted from warrens or plant denuded landscapes which are left vulnerable to the elements.

A rabbits generally will eat most flowers or the bark of woody plants, grasses of all types and most agricultural crops (vegetables).

Susceptible Plants

Rabbits mainly consumed grasses or garden vegetables and a broad range of ornamental plants.  In cool climates where snowfalls rabbits eat twigs, bark and buds from the dormant plants. When rabbits are hungry they will eat most plants but attached to this file are rabbit resistant plants that are less palatable. Their resistance will vary depending on the stage of growth as new shoots are very desirable to rabbits.

Cultural Control

Control methods include trapping, hunting and exclusion with the use of fences, all of which had a marginal success. Many predators utilise rabbits as a food source for example foxes, feral dogs and cats, hawks or owls and human hunters.

Biological Control

In Australia to biological diseases have had reasonable success. In 1950 Myxomatosis was released into the rabbit population and resulted in the numbers dropping from 600 million to 100 million. Remaining populations became immune and steadily increased numbers to 300 million by the 1990s.  The calicivirus was accidentally released in 1996 and culled populations significantly in regions of extreme heat but was less effective in cooler regions where the rabbits were exposed to a lesser calicivirus that immune them.

Chemical Control

Baiting and chemical repellents programs relied on the territorial habits of rabbits as they rarely forage further afield from their territorial areas.

Note

Landholders should seek advice from their local government agencies.  This advice will include fumigation or destruction of warrens, fencing and shooting.

DISEASE

   NAME

     Root Knot & Other Nematodes

     Meloidogyne & other species

Description

Root Knot Nematode or eelworms are transparent thin nematodes that are an organism up to 0.5mm long and attacks the roots by injecting saliva that stimulates the surrounding cells to form galls. The adult male lives in the soil and the female are found in the roots, laying up to 2,000 eggs in a mass in the soil adjoining the roots.

                 

Symptoms

Above ground the plant infected by Root Knot Nematode develops slowly and is stunted. During hot weather the plant wilts easily as it is unable to keep up with the transpiration rate and under extreme conditions the plant dies. The young nematodes attack the roots forcing there way up the root tips forming galls. On inspection the galls are found centrally located along the roots and are up to 20mm across. The galls slow the rate of nutrients and water passing through the plant and as the galls break down they allow opportunity for other diseases to enter the plant.

The roots are severely damaged if the galls are physically removed.

Other species of nematode have simular symptoms and are individually discussed below.

Source and Dispersal

The nematodes are found in soil or in infested plants and are dispersed by water, soil movement and attached to tools or shoes.

Nema Head

Favoured Conditions

It prefers sandy soil types and a warm moist weather conditions.

Life Cycle

Affected Plants

A wide range of plants are attacked by the Root Knot Nematode  including tomatoes, potatoes, carrots, tobacco, hibiscus, gardenia and roses. Some species of nematodes are plant specific such as (Meliodogyne incognita) which attacks Hemerocallis, Celosia and Viola species, forming small wart-like swelling on the roots.

Alternanthera, Begonia, Dianthus, Psidium, Thunbergia and Weigela species are attacked by the Root Nematode (Meloidogyne incognita). This forms small swellings on the roots causing the top growth to be stunted and not responding to improved culture. In cool climates it is found on plants in glasshouses.

Buxus species are attacked by the Meadow Nematode (Pratylenchus species) that turn the leaves a bronze colour and cause stunting of the plant. These microscopic nematodes enters through the roots and eventually result in the death of the plant.

Lagunaria patersonii is attacked by a simular nematode, the Root Burrowing Nematode (Radopholus similis) that feeds by burrowing in the outer root tissue.

Lavandula species that are grown in the northern United States are susceptible to the Peanut Root Knot Nematode (Melioidogyne hapla).  Berberis species are also susceptible.

Tulipa species are attacked by Bulb and Stem Nematode (Ditylenchus dipsaci) which forms brownish streaks along the stem that may blister and may cause wilting. The flowers petals become distorted and the general vigour of the plant poor.

                  Nematodes damage

Turf Grass are susceptible to several Parasitic Nematodes including (Helicotylenchus species), (Xiphenema Species), (Hemicycliophora species) and (Ibipora lolii). All turf grasses are susceptible and the nematodes are active from spring to autumn requiring a soil temperature 15 ºc. The leaves become chlorotic and have a weak appearance as a result of the damaged roots. Generally it is only a major problem when the nematode numbers are very high, otherwise control is not warranted.  

Cultural Control

Crop rotation in infected soils, avoid using plants from the Brassicaceae family for up to four years and plant species that are tolerant of nematodes, this will reduce numbers. Beds may be laid fallow for several seasons to deter nematodes, but numbers build up quickly once susceptible plants return.

Affected plants such as roses may have the bare roots dipped in hot water 45ºC for 15 minutes during the dormant period and contaminated growing media can be heat treated at 60ºC for 30 minutes before being used.

Any infested plants should be removed and destroyed or deposed off site.

Improve the soil structure and avoid acidity by the addition of lime or dolomite. Garden beds may also be pre planted with marigolds or mustard to deter nematodes, but should be removed or thoroughly composted prior to planting as they can push nematodes towards the crop. Green manure crops may be grown prior to planting and infested soil may require up to three seasons of manure crops to bring nematodes under control.

Biological Control

The encouragement of earthworms reduces nematode numbers as they accidentally eat them in there normal course of growth.

Chemical Control

The soil can be treated with a nematicide such as fenamiphos in a domestic situation. Commercial growers may fumigate the soil prior to planting with the appropriate chemicals.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Virus (Generally)

     Various Virus Species

Viruses can infect any plant and there are hundreds of types, but unlike fungi and bacteria viruses can only reproduce inside a living cell. Viruses are small requiring a magnification of x 10,000 to be seen and infection can be transmitted from one plant to another causing a variety of symptoms. Infected cells normal function, in the plant is diverted to aid the virus to reproduce by supplying nutrients and energy.  The virus can spread from cell to cell or travel through the vascular system in the plant and may only infect a specific part of the plant, normally the new growth or the whole plant.

Lethal Yellowing

This fatal disease is not a virus, but of uncertain origin that is associated with mycroplasmas or mycroplasma-like-organism and infects palms, particularly Cocos nucifera (Coconut Palm).

The symptoms include premature dropping of the fruit at all stages (shelling) and these have brown-black water soaked areas under the calyx.  The second symptom is the blacking of the new inflorescence as it is exposed from the spathe. Male flowers are also blackish and fruit will not set.

The third stage of this infection causes the lower fronds to turn yellow, eventually engulfing the entire crown. The fronds turn brown and easily fall from the plant and the infection kills the entire plant within 3 to 6 months with the crown falling away leaving a bare trunk.

Some palm species only exhibit the third stage making it difficult to diagnose, but generally a solitary frond will turn yellow, known as 'Flagging' and indicates Lethal Yellowing.

It is known to be transmitted by a plant-hopper (Myndus crudus) and currently there is no practical control.

Mosaic Virus generally is a viral problem that involves several viruses altering the production of chlorophyll in the leaf. It may only be seen on certain parts but the whole plant will be infected.

Symptoms

Mosaic Virus on Roses form variable yellow pattens on some of the leaves that are fine lined, imitating the veins with blotches or larger marks forming streaks.

Mosaic Virus on Cabbage, cauliflower and broccoli form yellow rings on immature leaves that turn shades of green as the leaf matures and eventually turning purplish-black in cooler weather.

The virus (Marmor iridis) infects Iris and Watsonia species leaves develop pale green streaks on the leaf that become larger then turn brown eventually killing the leaf. The virus prevails in the rhizome from season to season and is a serious problem reducing and damaging flower production.

Phloem Necrosis (Morsus ulmi) is a serious disease of Ulmus species. The initial symptoms occur at the apex and on branch tips where the leaves droop as the petiole is affected. The leaf margins curve upwards and the leaf turns greyish then yellow and then falls, overall giving the tree a sparse appearance. As the virus matures it infects the phloem tubes turning them yellowish, and then brown eventually killing the cells. The roots die and the entire tree may gradually decline over eighteen months, or in acute cases a tree may die within three weeks.

Pumpkin and zucchini are attacked from a virus commonly known as 'Watermelon virus' which affects the leaves by making them mottled in light or dark green and may become distorted. This inhibits the size of the plant and the fruit may have sunken areas with concentric rings.

Tobacco is infected by a Tobacco Mosaic virus (Marmor tabaci) and a Ring virus (Annulus tabaci).

Tulip Breaking (Marmor mite) causes yellowish-white, light coloured striping or spotting of the flower and reduces the size and vigour of the plant in Tulipa species. It may also affect the growth of the bulb and offsets and is more prevalent in double-flowering varieties.

Yellows (Chlorogenus callistephi) is a viral disease that causes leaves to turn yellow and produces shoots that are simular to Witches Broom or flowers that have poor colouring. The infection will not kill the plant as it overwinters and spreads infection from the living host via the Leaf Hopper (Macrosteles fascifrons). It is not found in the soil or in seeds but is a major problem for Aster species.

Source and Dispersal

The source and the dispersal vary depending on the particular Virus that is involved. In roses the virus overwinters on fallen leaves or pruned pieces of plant material. It is also found on infected plants and is spread by infected propagation material. Aphids transmit this Mosaic Virus.

Infected cabbage, cauliflower and broccoli are an excellent source for aphids, such as the green peach aphid to disperse.

Iris rhizomes are the source and the virus (Marmor iridis) is spread by aphids and infected rhizomes during propagation.

Phloem Necrosis is thought to be transmitted by the Elm Leafhopper (Scaphoideus luteolus) or by infected rootstocks.

Pumpkin and zucchini are infected from surrounding weeds or other infected plants by several aphids including the cotton aphid and the green peach aphid.

Generally plants are infected by viruses by, rubbing against each other or through grafting, budding and other vegetative means such as wounds. Insects also transmit viruses by sucking sap or transferring infected pollen.

Favoured Conditions

Viruses prefer warm humid climate.

        

Affected Plants

A wide range of plants are affected from a range of Mosaic viruses causing simular symptoms. These include roses, cabbage, cauliflower, broccoli, iris, pumpkin, zucchini, turnips, capsicum, swedes, stocks, alyssum and wallflowers. Shrubs and trees such as Ulmus species are also infected.

Abutilon species may be infected by the Mosaic Virus ((Marmor abutilon) which causes variegation of the leaves.

Aquilegi, Berberis Passiflora and Tulipa species are infected by the Cucumber Mosaic Virus (Marmor cucumeris). This causes yellow streaking or mottling in the leaves and dark coloured patches to appear on the flowers. It also stunts the plant and prevents flowering.

Lilium and Tulipa species are infected by the Mosaic virus (Marmor mite) causing yellow mottling on the leaves.

Palms are infected by Lethal Yellowing include, Pritchardia martii and Phoenix canariensis.

Non-chemical Control

With roses if the problem is minor it may be ignored as the flower production will be normal. Heavily affected plants should be disposed of.

Other plants that are infected should be removed and destroyed. The spread may be arrested by the eradication of aphids by applying soapy water.

Chemical Control

Once the virus is seen it is too late to spray. Preventative spraying to control aphids should be carried out in spring using Dimethoate. There is no satisfactory chemical control for viruses.

DISEASE

   NAME

     Rose Wilt

     Various Rose Wilt Viruses

Description

A combination of several viruses.  Commonly known as 'dieback'

Symptoms

It first affects young leaflets in compound leaves, by making them curl and arch backwards turning pale green to yellow.  The affected leaves then become dry and brittle, falling readily from the plant.  After defoliation the shoots or canes also brown and die, eventually causing the death of the plant.  Stunted plants with small leaves may also be infected although they don't show the obvious symptoms.

Source and Dispersal

Spread by other infected plants, aphids and propagation materials.

Favoured Conditions

No favoured conditions

        

Affected Plants

Roses only

Non-chemical Control

Remove and destroy infected plant and control aphid infestation to reduce the spread of the virus. This disease will kill the plant and there is cure is available.

Chemical Control

There is no chemical control for viral problems.

DISEASE

   NAME

     Rose Canker

     Coniothyrium fuckelii

Description

This is a fungal problem involving a weak fungus that enters the plant through wounds causing dieback.

Symptoms

The stems become discoloured (pale brown) usually from a pruned point, working its way down the stem and normally forming an angular intersection with live cambium. The bark splits or cracks and infected areas can develop tiny black fruiting bodies. Heavy infected plants eventually die, though certain varieties are resistant halting the spread of the infection.

                 

Source and Dispersal

The spores are found on infected dead plant material and can be dispersed by wind and splashing water.

Favoured Conditions

It prefers a warm humid conditions and plants that have a wounds derived from poor pruning techniques and insect or other damage, especially if water is allowed to settle on the wound.

        

Affected Plants

It specifically attacks rosed with some varieties more susceptible than others.

Non-chemical Control

Correct pruning techniques with sharp secateurs well below the infected areas. Ensure that there are no ragged edges, the angle of the cut allows water to run off and it is the correct distance from a bud.

Chemical Control

There is no satisfactory chemical control and prevention is imperative.

DISEASE

   NAME

     Powdery Mildew

     Various Powdery Mildew Species

Description

Powdery mildew covers arrange of fungal infections most with simular characteristics of white powdery areas appearing on the leaves and flowers.

     White powdery area     

Symptoms

Powdery mildew (Oidium species) affects the following five plant groups with slightly different characteristics.

Cucurbits firstly form white spots on the underside of the leaves. Under optimum conditions the fungus spreads to the upper surface covering the entire leaf causing it to die. It may also extend to the stems slowing the growth of the plant and may reduce the size of the fruit.

Grape leaves, flowers and fruit are attacked with the appearance of greyish-white powdery spots. Infected flowers set poor quality fruit and infected fruit splits open and dries out.

Pawpaw leaves become infected on the underside at first then spreading covering the entire leaf. The fruit forms irregular light grey spotted areas that damages the surface and under the surface causing the fruit to misshapen and reducing its market value.

Rose leaf and buds are covered in a fine white powdery coating and in severe cases it extends to the stems. When young leaves are infected they become distorted and older leaves develop blackened areas. Infected flower buds may fail to open and opened blooms may be discoloured or distorted.

Strawberries show different signs of infection with the leaf margins first rolling upwards then developing purplish irregular blotches along the veins.  The infected flowers may fail to set fruit and if fruit is produced it is small, hard fails to ripen. Semi mature fruit that is infected has dull appearance and may form cracks or split open.

The Powdery Mildew (Sphaerotheca lanestris) infects leaves and twigs. The under side if the leaf firstly has a white mealy growth that matures to felt-like brown mycelium that can cover the entire leaf, and the twig tips. It is only one of the many types that infect Quercus species.

Source and Dispersal

The spores overwinter in fallen leaves, dormant buds, seed and infested plants. It is dispersed by wind.

Favoured Conditions

Generally it prefers warm humid conditions, but failing to germinate when it is raining. The fungus that attacks Pawpaw prefers cooler conditions disappearing in the warmer months.        

Affected Plants

There are many plant species ornamental trees and shrubs that are attacked by Oidium species including; Roses, African Violets, Cucurbits, Grapes, Pawpaw, Strawberries, Hydrangeas, Ajugas, Antirrhinum, Oaks and Photinias.

Acer species are infected by the powdery mildews (Uncinula circinata) and (Phyllactinia corylea) but are not normally serious.

Aesculus species are infected by the powdery mildew (Uncinula flexuosa) which forms a white mold on the underside of the leaves.

Arenaria,Cuphea, Erica and Eschscholtzia species are infected by the powdery mildew (Erysiphe polygoni). This fungus is greyish or white and covers leaves or young shoots. Heavenly infected leaves turn brown and fall from the plant. The plant eventually dies.

Aster species are infected with the powdery mildew (Erysiphe cichoracearum) which is more prevalent on the lower part of the plant.

Ceanothus, Corylus, Platanus, Syringa and Weigela species are infected by the powdery mildew (Microsphaera alni) particularly London Plane. The mycelium forms a felt-like cover on the leaves.

Celtis species are susceptible to the powdery mildew (Uncinula parvula) and (Uncinula polychaete). This fungal problem can affect either side of the leaf, which can have spots or be completely coved in mildew. The fruiting bodies appear on the opposite side of the mildew.

Cornus species leaves are infected by the powdery mildew (Microsphaera alni) and (Phyllactinia corylea), covering the leaves in a whitish fungus.

Dahlia species are infected by the powdery mildew (Erysiphe cichoracearum) that forms white powdery areas on the leaf surface.

Lagerstroemia species are infected by the powdery mildew (Uncinula Australiana) that forms white powdery growth on the leaves and may also distort the infected foliage.

Populus and Salix species are infected by a white powdery mildew (Uncinula salicis) that produces black fruiting bodies with a curled tip, but is not normally a major problem.

                  Quercus robur

Quercus species are susceptible to several powdery mildew fungi including (Sphaerotheca lanestris), (Erysiph trina) and (Phyllactinia corylea). Generally white mealy growth appears on the leaves, normally on the underside turning the infected areas brown and then the leaf dies. The infection may spread to the twig tips causing dieback. Control may be difficult and unwarranted on large trees but nursery stock may be sprayed with a fungicide during susceptible periods.  

Rosa species are also infected by the powdery mildew (Sphaerotheca pannosa).

Rudbeckia and Senecio species are covered in white fungus (Erysiphe cichoracearum) which infects leaves, flowers and stems. This results in the plant becoming stunted.

Senecio species are infected by the powdery mildew (Sphaerotheca fuliginea) which forms circular white powdery areas on the leaves.

Spiraea species are infected by the Powdery Mildew (Microsphaera alni) and (Podosphaera oxyacanthae).

Ulmus and Rhododendron (Azalea) species are also infected by (Microsphaera alni). Circular patches of white powdery growth appear on the leaves.

Veronica species are sometimes infected by the powdery mildew (Sphaerotheca humili) causing a white coating to appear on the leaves. Not normally a major problem.

                 

Zinnia elegans are commonly infected by the powdery mildew (Erysiphe cichororacearum), which appears on both sides of the leaves as a greyish powdery cover and may be transmitted by seed.

Non-chemical Control

Choose less susceptible species and when planting space the plants to allow good air circulation. Avoid overwatering and try to keep the foliage dry. Affected plants may be dusted with powdered sulphur or sprayed with a milk mixture to discourage mildew. Vegetables that are infected with mildew should be removed and replaced with new young plants, as they are more resistant to infection.

Chemical Control

Prenatitive spraying during warm humid conditions using a suitable fungicide such as wettable sulphur, bitertanol, carbendazim, fenarimol and triforine helps control the problem.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Grey Mould

     Botrytis cinerea, B. elliptica

Description

Grey Mold, Shoot Blight, Petal Blight is a fungus problem that generally forms water-soaked spots that rot and produces greyish sclerotia (fungal resting bodies) on the surface. They can be found throughout the year on dead tissue and on live material during under ideal climatic conditions. Damaged areas such as a tear in a leaf or an opening made by an insect are more likely to be infected.

Grey Mold on Begonia species

Image by B. Sonsie

Symptoms

The fungus attacks stems, leaves, flowers and fruit. In roses the fungus is primarily attacks the flowers producing pink rings on the petals and buds that become brown and rotten. This may extend down the peduncle to the stems causing dieback.

In other plants oval yellowish to brown spots appear, then the centre turns greyish and dries out and in humid weather the spots spread, joining up and infecting the entire leaf. This infection may also occur on the stems, and flowers may form abnormally or brown off and die.

When lettuce is infected it starts at the base causing a soft brown rot that may extend up the stem killing the plant, and pears flowers become infected then spreading to the fruit. This develops a sunken brown area that is soft and eventually is covered in grey powdery spores.  

                  Botrytis Blight on Senecio cruentus

Botrytis Blight (Botrytis tulipae) infects leaves, flowers and stems with flecks of brown spots that merge to form light grey rotted areas that have brownish margin that may destroy stems. Affected areas are covered in a grey mould during humid conditions. The spores overwinter in dark brown sclerotia, which are found on the outer scales of the bulb or at the base of the stem in Tulipa species.

Grey Bulb Rot (Rhizoctonia tuliparum), which infects the bulbs of Tulipa species, attacking the base of the leaves and rotting the bulb. When bulbs emerge during spring in infected soil's they soon die off. The greyish mold tends to be dry.

Source and Dispersal

The sclerotia (fungal resting bodies) are found on dead plant material or in the soil and remain viable for many years. The spores are dispersed by wind or splashing water.

Favoured Conditions

It prefers cool moist climate with morning dew.

Affected Plants

Grey Mold attacks a wide range of plants including roses, fruit trees, pelargonium, ferns, grapes and cyclamens. Heliotropium , Amaryllis, Lilium and Hippeastrum species  are also infected.

Agave species are infected by two fungal Leaf Blights (Botrytis cinerea) and (Stagonospora gigantea) that severely damage the leaves particular during wet periods or from excessive watering.

Cactus species are infected by soft rot or Grey Mould (Botrytis cinerea). Stems and pads turn are greyish with the upper surface, rotting then collapsing.  The dieing tissue becomes slimy and is covered with grey mould that develops black sclerotia, which propagates the disease.  It is more prevalent under warm humid conditions and control methods include removing infected parts and destroying them.  In glasshouse situations ventilation should be improved and watering should be restricted to create a drier atmosphere.

Cereus species and other cacti are infected by Grey Mold causing the segments to become discoloured and as the rot progresses it tissue becomes slimy and collapses. Black sclerotia forms on the affected areas that are covered in grey mold during humid conditions.

Cuphea species are infected by this blight.

Orchids such as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalum species are infected by Grey Mold or Petal Spot (Botrytis cinerea). Petal and flower stalks form small brown spots.

Paeonia species are infected by Botrytis Blight (Botrytis paeoniae) causing the leaves and flowers to form a grey mold then suddenly collapse and die.

Pseudotsuga menziesii   Douglas Fir is infected by Leaf and Twig Blight (Botrytis cinerea). This is a serious problem in wet conditions and is difficult to control.

Ribes species are attacked by Cain Blight (Botryosphaeria dothidea). The infection causes the cains to become blighted and wilt. To control remove damaged wood and destroy.

Non-chemical Control

Remove and destroy infected plants or fallen leaves. When planting, space as to allow good air movement to reduce humidity. Bulbs that are infected should be discarded and take care that bulb scales are removed from the soil to prevent further infection. Cactus and succulents that are infected should have the damaged areas cut out, or discard the entire plant. Under glasshouse conditions improve the ventilation and reduce watering to create a drier atmosphere.

Chemical Control

Under humid conditions spray regularly using a suitable fungicide such as thiram, mancozeb, dichloran and chlorothalonil.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Fungi (General)

     Various Fungal species

Description

A fungus is a plant that lacks chlorophyll and conductive tissue. Generally they are made up of branched threads called 'hyphae' and collectively form a vegetative body called 'mycelium'. The fungus is small but the fruiting bodies can become very large up to 600mm across such as bracket fungi or mushrooms. Common fungi are mould and mildews. problem that attacks the roots causing them to rot.

Fungus can reproduce many ways but primarily it is asexually, simular to cuttings of a plant and often occurs with minute portions of the mycelium (spores) separating. The spores can be arranged in a structure such as a sporangia or pycnidia or develop without an enclosed structure called a "conidia". Either way the fungus propagates very rapidly.  Sexually reproduction occurs when two nuclei unite and form sexual fruiting bodies (zygospore).

Strelitzia reginae flower

Symptoms

Fungus attacks all the above or below ground level parts of the plant living within the tissue of the plant and are very small and not normally detected until the fruiting body appears. However parasitic types such as powdery mildew or rust are visible on the outer surface of the plant.

Fungi hyphae may be divided by cross walls and known as "septate" while others with no cross walls are known as "nonseptate". These are the fungi responsible for cell leakage as in rot.

Back Mold (Chalariopsis thielavioides) affects understocks of grafted Rosa species by inhibiting the development of callus. It is whitish-grey maturing to black and can be found in the pith of the rose stem.

Black Root Rot (Chalara elegans).This recently introduced fungal disease in Australia (1993) affect plants by blackening the root systems and turning leaves yellow or purple. It is difficult to identify specifically as other pathogenic root diseases and nutritional deficiencies have simular characteristics.  

The asexual spores are dispersed by wind or water. It is also transmitted on insects and in contaminated growing media or plants preferring humid moist conditions.

This fungus affects a wide range of ornamental plants including; annuals, perennials and shrubs. Examples are Begonia, Boronia, Camellia, Cyclamen, Fuchsia, Gerbera, Grevillea, Impatiens, Pansy, Petunia, Rosa species and Snapdragon.

Black Stem Rot (Pythium splendens) normally is a rot that occurs in cuttings turning the stem progressively black and shrunken. The leaves fall and the plant becomes stunted, eventually dieing.

Bleeding Necrosis (Botyosphaeria ribis) attacks and kills the inner wood causing the bark to split open and bleed sap giving it an oily appearance.

Blight (Endothia parasitica) is a serious pest of Castanea species, entering the twigs and small branches, and then progressively travelling throughout the tree killing it. It may form cankers on the base of the trunk or in the dead branches above with the amber coloured fruiting bodies pushing there way through the bark.

Copper Web ((Rhizoctonia crocorum). This fungal disease appears in defined patches causing the corms in the centre to become a black powdery mass. Corms on the outer ring of the patch that are partially infected forming a felty mass of violet threads on the corm scales. These threads extend into the soil and large sclerotia forms in the soil and on the corms. Healthy corms become infected from contaminated soil that contains mycelium and sclerotia.

Dry Rot (Phyllosticta concave) forms small circular spots that increase to a diameter of 30mm, and then becomes sunken as the cells collapse. The infected area develops minute black fruiting bodies.

Dutch Elm Disease (Ceratocystis ulmi) is a serious fungal problem of Ulmus species that initially causes yellowing then wilting of the leaves that turn brown and die. This may be seen on certain branches of the tree and on inspection under the bark the sapwood reveals brown streaks. A cross section of the affected branch displays round spots that are dark brown. This infection normally spreads quickly throughout, killing the tree in one to two seasons.

Dieback in Camellia (Glomerella cingulate) is a pathogenic fungus that infecting existing wounds such as leaf scars or mechanical damage, forming a sunken area (canker) that spreads around the stem causing die back. The affected plant has new shoots that are brown-black and the tips curl, forming a 'Shepard's Crook' appearance. The leaves also die but are persistent on the plant and the spores are found in soil or on other infected plants.

Curvularia Leaf Spot (Curvularia species) in Turf Grass. This is normally a secondary weak fungal infection that forms spots on the leaves that lengthens turning the leaves greyish. The leaf shrivels then dies and infected areas appear as weak patches in the turf. Preventive measures include minimising leaf wetness and excessive use of nitrogen fertiliser.

Fairy Rings Blue Couch     

Fairy Rings are a fungal problem in Turf Grass and is caused by several species including (Lycoperdon species), (Marasmius species) and (Tricholoma species). Rings appear in the turf as fruiting bodies or dead grass and as lush green foliage. The mycelia expand radially in the turf feeding on soil nutrients and organic matter with water present.

Under severs conditions the mycelia consume all available nutrients resulting in the death of the turf. Lush turf can result from a less developed infection, where the decomposing hyphal releases nitrogen. This available nitrogen may be beneficial to the turf but some forms of nitrogen are detrimental.

Leaf Blister (Taphrina coerulescens) appears as yellowish circular raised areas on the upper side and depressions on the underside of leaves, up to 15mm across. As the fungus spreads the leaf dies but remains attached to the tree and this infection is commonly found on Quercus species..

Leaf Blotch (Guignardia aesculi) forms small or large water soaked spots that are reddish with a bright yellow margin and form black fruiting bodies in the centre. The affected leaf and petiole have a scorched appearance before falling, found on Aesculus species

Grevillea robusta     Leaf Scorch

Leaf Scorch (Verrucispora proteacearum) is a fungal disease that infects leaves causing large parts of the leaf to turn grey-brown, giving the appearance that it has been singed by fire. Black fruiting bodies appear on the affected areas and the leaf soon withers then dies. New, mature leaves are affected during very wet periods towards the end of the branches and Grevillea and Hakea species are susceptible.

Melting Out (Helminthosporium vegans) forms bluish black spots with straw coloured centres on the leaves and may be found on the sheath, encircling it causing Foot Rot. It infects grasses particularly Poa pratensis. There is another fungus that is simular Helminthosporium Blight (Helminthosporium dictyoides) that infects Poa, Festuca and Agrostis species.

Pad decay (Aspergilus alliaceus) infects Cereus and Opuntia species and occurs at during periods of high temperature.  The yellow spores at the epidermal layer through wounds and germinate on mass causing the area to become soft and spongy. An anthracnose called Shot Hole is a similar forming brownish spots the turn grey, and then black destroying pads. Control methods include physically removing damaged pads and allowing the Sun to heal wounds.

Potato Gangrene (Phoma foveate) is a soil borne fungus that infects the roots during harvest primarly through wounds and develops during storage. The potatoes rot from the inside forming rounded depressions on the surface and have a strong odour of rotten fish.

Root Rot Fungi (Phymatotrichum omnivorum) and (Pellicularia filamentosa) cause the roots to rot and the plant suddenly wilts then dies.

Root Rot (Pythium debaryanum) forms water soaked dark brown streaks that affect all parts of the plant causing wilting then dieing. It infects Ranunculus species, it also infects cactus species by forming brown spotting and wilting that appears at the base of the plant then extends towards the top. It quickly spreads from plant to plant in collections and is controlled by avoiding over watering, excessive humidity and are using a sterilised soil when potting up.

This fungus also is responsible for damping off of seedlings in a glasshouse environment.

Spring Dead Spot     

Spring Dead Spot (Leptosphaeri species) is a fungal disease that infects Couch Grass. It first appears during autumn as pale bleaches areas up to 500mm (20in) wide and persists throughout winter. In spring the affected areas do not recover or recover slowly and on inspection the roots or rhizomes are rotted. Runners from the surrounding healthy turf will help with recovery and all signs of the problem disappear by mid summer.

Cactus species      Pachypodium species

Stem Rot (Helminthosporium cactivorum) forms well defined yellow lesions that mature into soft dark brown rot. It commonly infects Cactus species entering through the stomates or wounds. Heavily infected plants collapse and die.

Stem Rot or Basal Rot (Pellicularia rolfsii) is a soil borne fungus that infects the stem root junction and extends into the leaves. In orchids the leaves become discoloured, dry and detach from the base which is covered in a fungal growth that produces sclerotia. The sclerotia is whitish to yellow then becoming dark brown and can be viable for up to four years.

White Mold  (Ramularia desta f. odorati) occurs on both sides of the leaf and looks simular to powdery mildew but forms faint dull, reddish brown elongated spots on the leaf that may be depressed or along the margin where they have a watery appearance. Tufts of hyphae develop in the stomates.

Wilt (Ceratocystis fagacearum) causes leaves to curl then turn brown and the sap wood may also turn brown or black. Heavy infection may kill a tree within two seasons and is found on Quercus species and other ornamental trees.

Witches Broom may be a fungal problem that causes a proliferation of small axillary shoots to appear at the end of the branches. Little is known about this problem, though it affects a wide range of plants including Eucalyptus, Leptospermum and Pinus species.

Source and Dispersal

Fungus is found in the soil or on other infected plants and after releasing the spores, they are dispersed by wind or are transmitted in infected stock, insects and with splashing water.

Wilt is transmitted by infected root stocks, several species of insect and contaminated tools.

Dutch Elm Disease is transmitted by bark beetles such as (Scolytus multistriatus) and (Hylurgopinus rufipes). These beetles deposit eggs in the sapwood where the lava tunnel and pupate. The emerging beetles tunnel the bark and carry the fungus to fresh feeding sites on the tree. Infected beetles may also be transported to fresh sites in waist material.

Favoured Conditions

Prefers cool moist conditions with temperatures from 10º to 25ºC and is more common from autumn to spring when it is wet.    

        

Affected Plants

A wide range of plants and all parts can be infected by various fungal diseases. Bleeding Necrosis is found in Liquidambar species and Stem Rot or Dry Rot infects Cactus species such as Opuntia and Pelargonium.

Abies species are infected by several fungi that cause Leaf Cast which turn the needles yellow to brown then fall prematurely.

Abutilon species are infected by the Stem Rot (Macrophomina phaseolin) affecting the lower stems and is not commonly seen.

Achillea, Cuphea, Leucanthemum, Euphorbia species are infected by the Stem Rot (Pellicularia filamentosa) which enters through the roots and rots the base of the stem.

Alternanthera species are infected by the Leaf Blight (Phyllosticta amaranthi) which forms small brown spots on the leaves causing them to curl and die.

Aloe, Astrophytum, Copiapoa, Echinocactus, Espostoa, Ferocactus, Gymnocalycium, Kalanchoe and Schlumbergerera species are infected by Bipolaris Stem Rot (Bipolaris cactivora). This infection affects many cacti species causing rot in the stems with a blackish appearance.

Amelanchler is affected by the Witches Broom (Apiosporina collinsii).

Antirrhinum species are infected by the Blight (Phyllosticta antirrhini) that forms light brown spots on the upper-side of the leaf and on the stem. As the spots enlarge they turn greyish with black fruiting bodies in the centre, then become brown and killing the affected areas.

Begonia species are infected by the Stem Rot (Pythium ultimum) turning stems black then becoming soft and causing the plant to collapse. This is the same fungus that causes Damping-off.

Betula species are affected by the Leaf Blister (Taphrina bacteriosperma) which curls the leaves and forms reddish blisters.

Chamaedorea and other cain-like species are infected with Gliocladium Stem Rot (Gliocladium vermoseni) which forms a dark basil stem rot generally on damaged plants and produces orange-pink spores.  The mature leaves are first affected and eventually the stems or cains rot and die.

Crocus and Gladiolus species are infected by the Dry Rot (Stromatinia gladioli), which causes lesions on the corms and rots the leaf sheath.

Crocus, Iris, Tulipa, and Narcissus species are infected Copper Web ((Rhizoctonia crocorum).

Dianthus species are infected by Phialophora Wilt (Phialophora cinerescens) that causes the leaves to fade and plants to wilt. There is obvious vascular discoloration which is very dark. It is not found in Australia.

Erythrina x sykesii may be infected by the Root Rot Fungi (Phymatotrichum omnivorum).

Fern species are infected by Tip Blight (Phyllosticta pteridis). This blight produces ash-grey spots with purple brown margins and the fruiting bodies appear as black pimple like spots.  It is transmitted by air or moisture and in infected fronds become brown and die.  Control methods include sprang fungicide on leaves or reducing humidity and avoid wetting the fronds.

Forsythia species are infected by Stem Gall (Phomopsis species). It forms rounded growths along the stems causing them to die and look unsightly.

Gladiolus species are infected by Penicillium Rot of Corms (Penicillium gladioli). This disease forms deeply sunken reddish brown areas that become corky and produce a greenish fungal growth.

Hedera species are susceptible to several Fungal Leaf Spots including (Glomerella cingulate), (Phyllosticta concentrica) and (Ramularia hedericola). All of which cause yellowish spots that develop into dry brown blotches that kill the leaf.

Larix species are susceptible to Leaf Cast (Hypodermella laricis). This fungus attacks the needles and spur shoots turning them yellow at first then brown after which small black fruiting bodies appear on the leaves during winter.

There are several other fungi including (Cladosporium species) and (Lophodermium laricis) cause leaf blight or leaf casts.

Orchids such as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalum species are infected by Phomopsis Rot (Phomopsis species). This fungal problem forms a firm brown rot that appears on the leaves, pseudobulbs and rhizomes. The affected areas have yellow margins and the centre is covered in tiny black specks (fruiting bodies). Cattleya species are particularly susceptible. These plants are also infected by Psudobulb Rot (Mycolleptodiscus coloratus implicated). Dark spots appear on the pseudobulbs eventually causing extensive rot and killing the bulb.

Palms are infected by the fungus Butt Rot (Ganoderma sulcatum). The fungus entered the lower trunk normally as a result of mechanical damage (lawn mower). Symptoms include stunting of new growth and yellowing of the lower leaves. Fruiting bodies become evident at the base of the trunk. There is no effective control method and replanting in infected soil should be avoided.

Kikuyu Yellows     

Pennisetum clandestinum (Kikuyu) is susceptible to Kikuyu Yellows (Verrucalvus flavofaciens), thisis a water mould that infects the roots and causes them to rot. The infection extends up the stem and onto the leaves with yellow discolouration and can be limited to a small or large area up to 1m (3ft) wide.

It is found in warm temperate to sub tropical regions and dispersed in infected soil or plant material. There is no chemical control, nitrogen fertiliser masks the symptoms and complete fertiliser encourages stronger roots to fight the disease.

Pittosporum, Antirrhinum, Aquilegia, Echinops and Orchid species are infected by the Stem Rot or Basal Rot (Pellicularia rolfsii) commonly in the northern hemisphere and preferring humid glasshouse conditions.

Solidago species are infected by the fungal Scab (Elsinoe solidaginis) which covers the leaves and stunts the growth of the plant. Young plants may be killed.

Trillium species are infected by the stem rot (Pellicularia rolfsii) and ( Ciborinia trillii). This normally occurs in wet soils and is detrimental to the plants life.

Tsuga species are infected by Sapwood Rot or Butt Rot (Ganoderma lucidum) and (Coniophora puteana), which attacks the sapwood close to the bark, towards the base of the tree. Commonly killing the host.

Tulipa species are affected Blue Mold (Penicillium species) and the fungus (Rhizopus stolonifer) causing rot in the bulbs.

Vinca species are infected by the soil born Root Rot (Pellicularia filamentosa) which rots the stems and roots.

Viola species may be infected with the Scab (Sphaceloma violae) which attacks all parts of the plant including the seed capsule forming yellowish spots that turn brown and in leaves fall out. Stems and petioles can be girdled killing the upper part.

Viola species are also infected with the Stem Rot (Myrothecium roridum) which attacks the stems at ground level causing them to become dry and brittle. The leaves show symptoms by turning purplish-black and this fungus also infects Alcea and Antirrhinum species.

Non-chemical Control

Generally remove and destroy any infected plants or plant parts, when replanting, avoid using susceptible species for 3 years.  When growing crops space the plants to reduce the humidity and airflow and cultivate the soil to increase the drainage.  Remove weed growth from around the susceptible plants.

Avoid over watering the surrounding soil which encourages fungal development. In the case of trees remove any infected branches and heavily infected trees should be cut down and removed. This infected material should be disposed or burnt. Damaged trees should have the wounds dressed and sealed as a preventative measure particularly for Dieback in Camellia.

Deter Potato Gangrene by planting clean stock and be careful not to damage the crop when weeding. When harvesting the tubers choose a dryer period and be careful not to damage them.

     Fairy Rings

Fairy Rings in Turf are difficult to control and may appear or disappear sporadically. Cultural practice such as minimal thatch build-up, regular aeration and a reduction of organic matter spread on the turf will reduce infection.

Chemical Control

No suitable fungicides available, though drenching or spraying the soil with the fungicide dichloran helps control soil born fungi.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Anthracnose (General)

     Various Anthracnose Species

Description

This fungus is a casual organism that attacks leaves, flower, fruit, seed and twigs of the host.

Symptoms

Circular black spots appear primarily on the leaves or fruit but may also occur on the stems and flowers. The spots have a definite margin that may turn purple or black with age. As the spot enlarges the centre dries and may fall out giving the leaf a shot hole appearance or become sunken in some fruit while others form soft blackened areas. Infected leaves turn yellow then fall prematurely and fruit that is infected generally becomes black and rotten as it matures.

There are many variations in the symptoms depending on the type of plant and the species of fungus but generally as the fungal spots merge they form brownish to black dead areas.

Plane Anthracnose (Gnomonia platani) first appears on young leaves and as the leaves mature light brown spots appear along the veins and eventually engulf the entire leaf causing death. The twigs are also infected and often fall to the ground when dead and branches die after cankers appear lower down. This is a serious problem for Platanus occidentalis in North America.

Anthracnose in turf

The Anthracnose (Colletotrichum species) and (Microdochium bolleyi) infects winter Turf Grasses. At first yellow patches appears which turn red brown then the leaf blades turn whitish and die. This forms bare areas and (Colletotrichum species) forms spine-like fruiting bodies that are tiny and can only be seen using a hand lens.

Wither Tip (Colletotrichum gloeosporioides) forms spots on the leaves and flowers and the stems form cankers that cause wilting at the top of the branches. Commonly found on Aucuba species.

Source and Dispersal

The fungal spores are dispersed by wind from infected plants or parts of plants. It is also dispersed by splashing water or contaminated stock.

Favoured Conditions

The fungus prefers cool humid climates and is not commonly seen in warm coastal regions and may continue living in dead wood, leaf litter or harvested fruit.

Affected Plants

The Anthracnose species is found shrubs, vegetables, trees particularly fruit trees such as mango or macadamia and large trees such as Platanus species.

                  Acer negundo

Acer species are infected by the Anthracnose (Gloeosporium aporcryptum). Irregular shaped light brown spots appear on the leaf, joining to form large dead brown areas and giving the leaf a scorched appearance. Leaves may be fully or partially damaged, often causing the leaf to die prematurely. During constant wet weather this can become a serious problem. Acer saccharinum (Silver Maple) and Acer negundo (Box Elder) are particular susceptible and small plants may be sprayed with a fungicide as the new foliage appears to help control infection

                  Agave species

Agave species are susceptible to Glomerella Leaf Blight (Glomerella cingulate). This causes dark coloured depressed spots to appear on the leaves. The leaf apex dies and the spreading rot in Orchid species can infect the pseudobulbs causing the death of the plant.  

Orchids such as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalum species are infected by Glomerella Leaf Blight (Glomerella cingulate).

Agrostis palustris (Bent Grass) is particularly susceptible to Anthracnose (Colletotrichum species) and (Microdochium bolleyi), but this fungal problem is also found on Cynodon dactylon (Couch), Lolium perenne (Ryegrass) and Festuca arundinacea (Tall Fescue). These grasses are infected in areas of poor drainage or where leaf wetness is prolonged. Low soil fertility may also contribute to infection and it is commonly found in coastal regions.

Anthurium species are susceptible to the Anthracnose (Gloeosporium minutum) which causes circular spots on the leaves, along the margins. These meld together forming dead brown areas that dry and fall out. It is commonly found in a glasshouse situation. The spadix is also infected by Spadix Blight (Colletotrichum gloeosporioides) which forms dark spots that enlarge, spoiling the flower.

Antirrhinum species are susceptible to the Anthracnose (Colletotrichum antirrhina) which attacks stems and leaves forming sunken oblong spots that are yellowish with a brown margin.

Cactus species are susceptible to anthracnose causing shot hole disease, which attacks the pads of Opuntia species (prickly pear). It appears and during the hot humid months of the year and is distinguished by the appearance of small brownish spots that turn grey with black spores under the drying skin. Control methods include removal of infected pads and treating wounds with disinfectant.

Digitalis species are infected by the Anthracnose (Colletotrichum fuscum). This fungus forms rounded spots that are purplish-brown and may have a purplish border. Fruiting bodies appear in the centre as the spots enlarge.

Leucadendron and Leucospermum species are susceptible to Anthracnose (Colletotrichum gloeosporioides). This causes the new growth to die back, leaf spots appear and cankers to form on the stems. It also causes damping-off of seedlings, which can be a major problem for Protea species as the fungus can be carried in the seeds.

Limonium species are infected by Wither Tip (Colletotrichum gloeosporioides). This is a serious disease causing spots on the leaf, flower and stems or rotting the crown.

Ribes species are attacked by (Pseudopeziza ribis). This infection causes circular brown-black spots on the leaves and premature defoliation of the plant. The spots may also appear on the petioles or stems. Infected areas may be sprayed with wettable sulphur weekly.

Schizanthus species are infected by Anthracnose (Colletotrichum schizanthi) which forms eater soaked areas on the stems and petioles, preferring new growth and maturing with canker-like lesions that girdle the stems.

Tilia species are infected by the anthracnose (Gnomonia tiliae), which forms light brown spots on the leaf venation, towards the tip and can defoliate an entire tree.

Spot Anthracnose (Elsinoe ilicis) infects Ilex cornuta forming black spots that may lead to leaf disorder.  Opuntia species are infected by (Gleosporium cactorum) in warmer regions.

Vaccinium ovatum is infected by (Gloeosporium minus) and commonly known as Fleck and appearing on the leaf and stems.

Viola species are infected by (Colletotrichum violae-tricoloris) which produces brown blotches with black margins on the leaves.

Non-chemical Control

Avoid watering plants from above or wetting the foliage especially in the late afternoon. When planting allow space between each plant for good air circulation. Remove affected foliage or wood by pruning and dispose off site.

Turf grasses should have well drained soils, high fertility and avoid excessive watering to reduce possible infection.

Chemical Control

Regular spraying where possible during the periods that are favourable for fungus development. Fungicides include;

Systemic types, Biteranol, carbendazim, triforine

Protectants; chlorothalonil, copper oxychloride, mancozeb, thiram, zineb

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Black Spot

     Marssonia rosae

Description

A fungal problem that is wide spread throughout the world.

Symptoms

Black spots appear on the surface of the leaves and are up to 12mm across. As the blackened area increases in size or melds with another it causes the leaf to curl then turn yellow. The leaves eventually die and fall, defoliating the plant.  The fungus also infects the stems causing dieback and loss of vigour in the plant. Affected plants tend to produce smaller blooms.

                 

Source and Dispersal

The spores are found on infected plants and fallen leaves and are distributed by wind.

Favoured Conditions

The disease is more prevalent during warm humid conditions with temperatures around 12ºC to 25ºC.        

Affected Plants

Rose plants with some of the cultivars more susceptible. There is a form of Black Spot (Coniothyrium hellebore) that attacks Helleborus species that forms concentric rings and turns the leaves yellow, flowers fail to open and stems die.

Non-chemical Control

Avoid overhead or late afternoon watering and keep foliage dry. Prune off infected parts and burn, heavily infected plants should be discarded.

Space the plant in order to improve air movement and use correct pruning techniques to open the centre of the plant.

Chemical Control

Chemical should be sprayed as the climatic conditions approach ideal and continued throughout that period at regular intervals. There are many chemicals on the market that can be used such as, bitertanol, carbendazim, chlorothalonil, copper oxchloride and zibeb.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Collar Rot

     Phytophthora citrophthora

Description

Pathogenic, Fungal, (soil)

Symptoms

Black soft areas appear at the base of the trunk becoming harder then splitting. Gum may ooze from the affected areas and as the rot spreads the tree is ringbarked and dies. Affected trees show signs with a lack of vigour and turn blackish at the base.

Ring barking     

Source and Dispersal

The spores are dispersed by splashing rain and spread in infest the soil.

Favoured Conditions

It prefers wet humid conditions in soil that is poorly aerated and drained around the base of trees. Weed growth around the trunk creates a favourable condition.

Affected Plants

Citrus species vary in resistance with cultivars such as 'Eureka" or ' Lisbon' as most susceptible.

Non-chemical Control

Prepare the soil before planting or around existing trees by improving the drainage and aeration. Remove weed growth and mulches from around the base of the trunk. Current infections may be treated by exposing the surrounding soil to air, lowering the humidity and clean back damaged areas on the trunk to fresh tissue. Avoid moisture being applied to the area.

Select plant that have a resiant rootstock to the fungus.

Chemical Control

There is no satisfactory chemical control.

Note

Always read the label for registration details and direction of use prior to application of any chemicals.

DISEASE

   NAME

     Fasciation

     A Mutation

Description

Non-pathogenic

Symptoms

Stems become enlarged and flattened and are normally associated with bunches of smaller leaves at the top of the affected areas.

                  Fraxinus augustifolia

Source and Dispersal

This is a genetic mutation and little is known of its source or its dispersal.

Favoured Conditions

It is unknown what conditions are favourable.

Affected Plants

Many ornamental plants are affected these include, Senna, Allocasuarina, Cottoneaster and Daphne, and Rosa species. Actinotus helianthi may also be infected.

Trees such as Fraxinus augustifolia are also affected causing deformities in branches or stems.

Non-chemical Control

Prune off  affected parts.

Chemical Control

Not applicable

DISEASE

   NAME

     Mosaic Virus

     Various species

Description

This is a casual viral organism that affects the leaves of the host.

Symptoms

Some of the host plant leaves becomes mottled towards the leaf margins, or completely yellow giving a variegated or marbled appearance. The leaves may also become distorted or crinkled. Flowers are also affected showing signs of colour breaking by forming patterns on the petals.  

                  Rosa species

Rose Mosaic (Marmor rosae) causes intermittent irregular yellowish areas on the leaf surface of Rosa species. These chlorotic pattens tend to be along the mid rib but are also found along the margins.  

Source and Dispersal

Propagation from infected plants will spread this disease. Certain species are also spread by insects such as thrips or aphids.

Favoured Conditions

There are no known favoured conditions but generally appears during the growing period.

        

Affected Plants

Many plants are infected by various Mosaic viruses such as Fragaria, species.

Camellia - particularly japonica and reticulata are infected by the Camellia Mosaic Virus. This virus is not thought to be transmitted by insects but through propagation methods such as grafting.  The yellow mottled appearance on the leaves could also be attributed to genetic changes, as all affected leaves develop a simular pattern.

Delphinium, Limonium, Mathiola, Primula, Petunia and Cucumis species are infected by the Cucumber Mosaic Virus (Marmor cucumeris).

Laburnum anagyroides is infected by the Laburnum Vein Mosaic virus which causes vein banding on the leaves.

Orchids such as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalum species are infected by Cymbidium Mosaic Virus and Tobacco Mosaic. Cattleya and other orchid species exhibit leaf necrosis in the form of rings or streaks and necrotic sunken areas that are brown or black on the mature leaves.  

Non-chemical Control

Remove and destroy contaminated leaves upon sight and take note that even if the plant appears to have only a little damage, the whole plant will be infected and replacing it is the only way to eliminate the problem.

Chemical Control

There is no chemical solution for viral infections.

DISEASE

   NAME

     Downy Mildew (General)

     Various Downy Mildew Species

Description

Generally Downy Mildew may occur as a result of several fungal species, but have simular symptoms. The fungus is normally host specific.

Symptoms

The upper leaf forms yellowish, green or translucent patches that become enlarged and eventually the leaf turns yellowish-brown, wilts and dies. It can extend down the petioles onto the plant causing it to collapse and on the underside of the patches downy spores form, these may be grey to mauve or brown to purplish.

                 

The Downy Mildew (Plasmopara halstedii) forms pale green spots on the upper surface of the leaves with corresponding white felty areas on the underside. The affected leaves contract, turn brown and die; commonly found on Senecio species.

Downy Mildew in Rose (Peronospora sparsa). Angular purplish to dark brown spots or areas develop on the upper leaf surface and under humid conditions, the underside of these areas develop fury fruiting bodies. Young and heavily infected leaves turn brown and fall. The flowers stalks and stems are also attacked with purplish blotches or streaks that may cause them to split. Young growth that is infected dies off and if the flowers are affected in bud blooms become deformed when open.

The spores overwinter on infected plants and fallen leaves and are dispersed by wind infecting new growth during spring.

Downy Mildew in Stocks (Peronospora parasitica). The upper leaf forms yellowish green patches that become enlarged and eventually the leaf becomes yellow, then wilts and dies. It also infects the stems and on the underside of the leaves patches downy grey to mauve-white pustules form where the spores are arranged in rows. This fungus is soil born and commonly dispersed by infected plants.

Source and Dispersal

It is normally found or dispersed on other infected plants. The spores are also spread by wind but are unable to germinate in dry conditions, requiring moisture on the leaf and a humid environment to grow.

Favoured Conditions

It prefers warm humid days with cool nights and spread quickly in closely planted seedlings or plants.

Affected Plants

A wide range of vegetables, annuals, perennials and shrubs are affected. Plants such as stocks and seedlings are at most risk commonly causing the plant to collapse and die.

Aster species are infected by the downy mildew (Basidiophora entospora).

Mathiola incana and Arabis species is infected by (Peronospora parasitica) causing stunting with downy mold on the underside of the leaves. Seedlings are at most risk commonly causing the plants to collapse and die.

Rudbeckia species are infected by the downy mildew (Plasmopara halstedii) causing yellowing of the foliage, wilting and in some cases death of the plant.

Turf Grasses are susceptible to the downy mildew (Scleropthora macrospore), which may not appear downy on the leaves but leaves affected are stunted, thickened or become broad and only under severe cases small yellow patches up to 100mm wide appear in the turf.

Veronica species are infected by the downy mildew (Peronospora grisea). Symptoms include leaves form pale spots on the upper surface while greyish mildew forms correspondingly on the underside.

Viola species ate infected with (Bremiella megasperma) which forms irregular greyish spots on the upper surface and felt-like growth on the underside.

Non-chemical Control

Infected plants must be removed and destroyed and avoid over planting seedbeds. Avoid watering from above or over watering to reduce humidity.  When planting out space the plants to allow good air circulation as a dry atmosphere halts or reduces the infection. Select resistant plant species when planting.

Improve drainage and aeration of the soil in affected Turf grasses and avoid overwatering.

Chemical Control

With seedlings drench the soil with a systemic root absorbing fungicide such as furalaxy. Plants can be sprayed with a protectant fungicide such as copper oxychloride or zineb if the weather conditions are favourable for fungal attack. Be certain to thoroughly cover the under side of the leaves.