Fagus sylvatica

PEST

   NAME

     Woolly Aphid

     Eriosoma lanigerum

   ORDER

     Hemiptera

   FAMILY

     Aphididae

Description of the Pest

Females are 2mm long, globular, purplish brown insects that are covered in woolly white wax threads and greyish powder that is secreted from there bodies.  Adults are almost exclusively females, some of which may be winged and produce about 100 brown flat larvae. Nymphs are smaller than adults and pale in colour. Woolly aphids are sap sucking insects that produce honeydew, encouraging sooty mold.

Appearance and Distribution of the Pest

This insect is found through the world and is primarily found on apple trees. It is first seen on the new woody growth where the bark is thin, buds or in wounds in the bark, forming colonies. Nymphs are distributed by wind or on clothing and infested plant material.

Life Cycle

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

The species reproduces asexually; 2-20 live female nymphs are produced daily. Some sexual forms produce eggs, which seldom hatch. Many generations appear each year. The immature form overwinters on the roots or near the ground on the trunk of the host.

Period of Activity

During winter (and during periods of unusually high temperatures), most activity is below-ground, or in sheltering cracks in the lower trunks of host plants. Otherwise, the aphids are most active through Spring and Summer, especially during humid conditions.

Damage Caused

Larvae suck sap on lateral growth, shallow roots and trunks of apples, where the wood is thin or has been broken as a result of injury (including old feeding sites). Feeding sites may become gnarled and trunks & roots disfigured; buds are destroyed and the overall vigour of the plant is reduced with less new growth. Excreted honeydew produces sooty mould, to which the waxy threads adhere; this interferes with photosynthesis, weakening the plant. Heavy infestations cause fruit to fall prematurely.

Susceptible Plants

Apple trees are the main host of this insect and are more susceptible when in poor health, this leads to low quality fruit and an overall loss of vigour.  Ornamentals such as Crab-apples, Cotoneasters, Hawthorns are also attacked.

Cultural Control

It is very difficult to eradicate this pest but numbers can be kept down to a non-problem level. Infested parts may be removed; however, reinfestation is likely due to migration of larvae from infested roots. Note that some host species have resistant rootstocks and are preferred plantings. When mowing or wiper-snippering around susceptible plants take care not to damage the bark on the trunk. Bark eating animals such as cattle, sheep or wallabies should be kept away from the plants. Other preventive measures include pruning during summer when the wounds heal quickly and all wounds should be painted with a antifungal sealant.

Biological Control

Ladybirds, lacewing lava, syphid fly and parasitic wasps generally keep the aphid in check if the plants are not sprayed.  

Chemical Control

Winter oil may reduce some over-wintering larvae populations. Insecticides, if used, will also destroy the parasitic wasp, which is an introduced and effective predator.

Note

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

PEST

   NAME

     Caterpillars (General)

     Various species

Description of the Pest

There are many types of caterpillars from moths or butterflies, cutworms, bag moths, case moths, leaf rollers leaf skeletonises. The larvae generally eat leaves, seeds, flowers or buds by chewing out pieces. The size of the piece will depend on the size of the caterpillar and generally they are voracious eaters. The method of eating varies such as the leaf skeletoniser which leaves a network of veins or whole leaves are consumed.

The larvae have mainly 4 or 5 pairs of prolegs except Loopers which have 2 -3 pairs of prolegs. The number of prolegs can help in identifying the insect.

Small and Large Types     

Casuarina Moth (Pernattia exposita) is gregarious, brown with a large head and tufts of hairs that line the slender body. It grows to 25 mm long and forms a tightly woven cocoon on the side of branchlets. The large female adult moth has a stocky body and generally slow moving, the male is smaller.

The larvae cause extensive damage to A. littoralis, A. stricta, C. cunninghamiana, C. glauca, and C. equisetifolia.

The hairy larva feed on the 'leaves" phyllodes, and stems, this can lead to ringbarking and death of branches.

Monitoring

Place sheets on the ground and disturb (shake) the tree for the larva drop to the ground on silken threads.

Spruce Budworm (Choristoneura fumiferana) is a reddish brown with a yellow stripe on its side and chews on the opening buds and the needles of the host. The adult moth is dull grey with brown bands and spots on the wings, appearing in early summer.  The larva is very destructive in northern hemisphere coniferous forests.

Banksia Moth (Danima banksiae) is a caterpillar up to 60 mm long and is brown with black and white markings on its sides and when disturbed it arch backwards and reveal an extruded red underside, close to its head. The grey adult moth has an orange coloured body with a wing span that is up to 80mm across with black and white markings.

Banana moth (Opogona sacchari) is in the order Lepidoptera. This nocturnal moth as a wing span up to 25 mm wide and is bright yellowish brown with a dark brown spot on the wings.  It has a life cycle that lasts approximately 3 months with the eggs hatching in 12 days and the whitish larva with a reddish brown head is up to, 26 mm long, and lives for 50 days at 15° C. In warmer climates life cycle is quicker with up to eight generations per season. The female moth uses a ovipositor to lay up to 500 eggs in groups of five amongst the crevices of the plant. The voracious larvae tunnel into the plant, avoiding light.  In bananas it infests developing fruit and in ornamental plants it prefers the fleshy stems, particularly in cacti, begonias, African violets and is also a serious pest of Pritchardia and Chamaedorea species. Symptoms include tunnelling activity, which may be difficult to see then dead areas appear on the stems. As the caterpillars destroyed xylem tubes leaves begin to wilt and the plant may collapse and die. In European countries it is a glasshouse pest that is controlled chemically.

Pritchardi species      Banana moth larvae

European Pine Shoot Moth (Rhyacionia buoliana) lays eggs on Pinus species during late spring on the new buds and the emerging caterpillars in late summer feed on the shoots causing them to fold and become deformed, eventually dieing.  A major problem in the pine forests of the northern hemisphere

Large Grass Yellow Butterfly (Eurema hecabe) is a small attractive yellow butterfly. with a wing span of 40 mm that lays its eggs on the feathery leaves on Acacia species such as A. baileyana, (Cootamundra wattle), A. spectabilis (glory wattle). Other plant foods include Cassia spp, Caesalpinia spp, Senna spp. Albizia julibrissin (silk tree) A. paraserianthes (Albizia) sp Aeschynomene sp (Budda pea), Indigofera australis (Australian indigo's), Sesbania cannabina (yellow pea-bush), Senna surattensis (Glossy shower), Leucaena leucocephala (wild tamarind).

The small lava are up to 15mm long, green with white lateral bands and feed on the leaves at night in small groups, hiding under the leaves during the day. Large infestations may strip trees and require control. The larva of this insect does not feed on grasses. The adults are important pollinators of many Australian native plants. Various sub species of this insect are found through out Asia.

Gypsy Moth (Porthetria dispar) lava is a hairy grey caterpillar that is marked with blue and red dots along its back and can grow to 75mm long. It is capable of defoliating large trees and is a major problem for several species. A major problem in the northern hemisphere.

Lawn Armyworm

Lawn Armyworm (Spodoptera mauritia) is a plump, smooth caterpillar that is darkish brown to black with multiple stripes and pattens along its body. It can grow to 50mm long and tapers from the head. They are gregarious and move around in groups, like an army. If disturbed the larva drop to the ground and curl up, "faking death"  The larva pupate in the soil. They are a pest of grasses and monocotyledon crops mainly.

This insect is also found throughout Asia.

Monitoring

Drench a known area with old fashion soap 2L / 1000 cm 2. Note the numbers of larvae emerging.

Oblique-banded Leaf Roller (Choristoneura roseceana) lava feeds on the leaves and forms a nest by drawing the leaf margins together using silk threads. The adult moth is up to 25mm across the wingspan and is reddish brown with three darker brown bands across the wings. This is a problem in the apple growing areas of North America. It feeds on Maples, hawthorns, crab apples, Blackberry (bramble) and raspberries.

Red Humped Caterpillar (Schizura concinna) is a lava has a red head and humps with yellow and black strips on the body. It grows from eggs that were laid on the underside of leaves by the adult greyish brown moth that has a wing span up to 30mm across.

Tailed Emperor Caterpillar (Polyura pyrrhus spp. sempronius) adult is a large butterfly with a wing span up to 110 mm with four long tapering tails and the rear of the wings. The fleshy caterpillar with four obvious backward facing horns on a shield shape head. It is dark green with yellowish bands and transversal stripes over its back and grows up to 80 mm in length.

It is commonly found solitary or in small groups. Found over much on mainland Australia. The adults are attracted to overripe fruits they become drunk on this and so are easy to capture. The larvae feed on many plants including, Acacia baileyana (Cootamundra Wattle, A. spectabilis (Glory wattle), Delonix regia (Poinciana), Cinnamomum camphora (Camphor laurel) Robinia pseudoacacia (Black or false locust) Lagerstroemia indica (Crepe Myrtle), Argyrodendron actinophyllum (Black booyong), Celtis spp (Hackberry), Brachychiton spp (Kurrajongs) Gleditsia triacanthos (Honey locust).

Verbena Moth (Crambodes talidiformis) lays its eggs on the outside of the plant and the small green caterpillar that attacks seed pods by entering and eating the contents. It half emerges while pupating appearing as a small brown bump circled by a black ring. Native to North America

White Tussock Moth (Hemerocampa leucostigma) produces lava that is up to 50mm long. It has a red head with a yellow body that is marked in black and has four tufts of hair. The caterpillars pupate on the branches and the eggs laid by the adult moth overwinter on the trunk and are covered in a white waxy material. They are found on Aesculus species. A pest in North America of Oaks.

Life Cycle

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

Distribution of the Pest

Many species are found throughout the world from tropical to temperate regions and most of the adults are capable of by flying

Many hairy caterpillars can be irritating      Leaf Skeletonised

Period of Activity

Most active during the warmer months from spring to autumn.

.

Damage Caused

Leaf Rollers

Caterpillar Inside a Tomato

Susceptible Plants

A wide range of native and exotic plants are attacked and can be a major problem in commercial crops or turf grasses. Plants with soft-textured foliage (eg vegetables, some indoor plants) are preferred, but trees and shrubs are commonly attacked.

Malvaceae Abutilon spp, Hibiscus spp and other members of the family are attacked by the castor oil looper, Croton caterpillar (Achaea janata) which feed on leaves. The tip borer Cotton tipworm (Crocidosema plebejana), Rough bollworm (Earias huegeliana) which feeds on young stems, flowers and seeds. A leaf miner (Phyllonorycter spp)

Acer saccharinum and Fagus species are attacked in North America by the Maple Leafcutter (Paraclemensia acerifoliella) that forms a small cocoon in leaves that it skeletonises.

In Australia Case moths and Painted apple moths (Teia anartoides)

Ailanthus altissima is attacked by the Cynthia Moth (Samia cynthia) light green lava, which eats leaves and the Ailanthus Webworm (Atteva aurea) which are olive-brown caterpillars that form web nests in the leaves.

Antirrhinum species are attacked by the Leaf Tier (Udea rubigalis) lava. This caterpillar eats pieces out of leaves and binds them together forming a nest. It is more commonly found in glasshouse culture.

Berberis species may become infested with the Barberry Worm (Omphalocera dentosa). This small caterpillar is black with white spots, up to 14mm long and feeds on young shoots and leaves. It also binds the shoots with a silken thread to form a nest.

Betula species are attacked by the Leaf Skeletonizer (Bucculatrix canadensiella). The small adult moth has brown wings with a whitish underside and its yellow green, 7mm long lava skeletonise the undersides of the leaf turning it brown.

Brachychiton, Senna and feathery-leaved Acacia species are attacked by the Tailed Emperor Caterpillar, particularly in dryer periods.

Catalpa species are attacked Catalpa Sphinx (Ceratomia catalpae). This large yellow and black Caterpillar grows to 76mm long and attacks the leaves.  Large infestations can completely stripped a tree and control is carried out by spraying.

Calendula and Canna species are attacked by the Woollybear Caterpillar (Diacrisia virginica) which has yellow and black lines down its body is up to 50mm long and eats the leaves or flower buds. In Canna species the chewed holes tend to be in a straight line across the leaf.

Celtis species are attacked by the Spiny Caterpillar (Nymphalis antiopa) which is reddish, up to 50mm long and feeds on the leaves at the top of branched in groups.

Cheiranthus species are attacked by the Diamond-backed Moth (Plutella maculipennis) lava, which is a small green caterpillar to 14mm long that feeds on the underside of leaves and may form a shot hole appearance. It forms a small cocoon to pupate in and in cooler climates it may be found in glasshouses.

Cotinus, Fraxinus, Betula, Cornus, Crataegus, Aesculus, Tilia, Acer, Quercus and Populus species are susceptible to attacked by the Oblique-banded Leaf Roller (Archips rosaceana)

Iris and Antirrhinum species are attacked by Verbena Moth.

Picea, Abies, Tsuga and Pinus species are attacked by Budworm commonly found in the northern hemisphere.

Populus and Carya species are attacked by the Red Humped Caterpillar which chews the leaves.

Quercus species are attacked by several caterpillars including Saddleback Caterpillar (Sibine stimulea) and Datana Caterpillar (Datana ministra) that feed on the leaves.

Samanea saman is attacked by several caterpillars (Ascalapha odorata, Polydesma indomita and Melipotis indomita). These caterpillars defoliate the tree but cause no long term problems.

Spiraea, Fraxinus, Betula, Cornus, Crateagus, Acer, Quercus and Populus species are attacked by the Oblique-banded Leaf Roller.

Ulmus, Salix, Crateagus, Tilia, Quercus and Populus species, Pseudotsuga menziesii are attacked by the Gypsy Moth (Porthetria dispar).

Ulmus species are attacked by the Spring Cankerworm (Paleacrita vernata), which chews the leaves during spring and the Fall Cankerworm (Alosphila pometaria), which also eats the leaves during autumn. Ulmus  species are also attacked by several caterpillars including the lava of the Leopard Moth (Zeuzera pyrina) and the Tussock Moth (Hemerocampa leucostigma).

Cultural Control

Small numbers may be removed by hand and squashed while others species such as the Casuarina Caterpillar drop to the ground when disturbed by hitting with a stick or shaking the plant. On the ground they can be squashed or collected and placed in a bucket of soapy water.  All rubbish around plants and glasshouses should be cleared as certain moths overwinter in such places.

Biological Control

There are many natural predators that reduce numbers including birds, lizards, frogs; other predators are wasps, viruses, and fungi.

Chemical Control

The small plant may be sprayed using Pyrethrum-based insecticide to reduce numbers or dusted with an equally environmental friendly chemical. In severe cases crops may be sprayed with Carbaryl.

Note

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

PEST

   NAME

     Oak Leafminer

     Phyllonorycter messaniella

   ORDER

     Lepidoptera

   FAMILY

     Gracillariidae

Description of the Pest

The adult is a very small moth; the cream-coloured larvae are up to 5mm in length and have chewing mouth parts.

Appearance and Distribution of the Pest

This is an European native insect and is found commonly throughout Australia.

Life Cycle

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

Period of Activity

Most active in cool to mild temperate climates.

Damage Caused

Larvae burrow into the underside of leaves, where the eggs were laid, causing blistering, which appears on the upper surfaces as pale blotches. The damaged leaves become brown and papery, resulting in a burnt appearance and leaf loss.

Susceptible Plants

Favoured plants include oak, chestnut, beech, apples, liquidambar, stonefruit, and apples.

Cultural Control

Removal and destruction of fallen leaves is a preventative measure to reduce numbers in the subsequent season.

Biological Control

None known.

Chemical Control

During early infestations, when larvae are active, systemic pesticides may be effective.

Note

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

DISEASE

   NAME

     Coral Spot

     Nectria cinnabarina

Description

A casual fungal problem that attacks broad-leafed shrubs and trees.

Symptoms

The fungus causes the twigs and branches to die back followed by rounded pustules that are pink to coral red producing spores. The branches become brittle and in extreme cases the plant dies.

Source and Dispersal

The fungus is derived from other infected plants and the spores are dispersed by wind. Infection occurs by entering the plant through wounds, normally the result of poor pruning techniques or wind damage.

Favoured Conditions

There are no current references to favoured conditions but generally fungal attack occurs during humid weather.

Affected Plants

A wide range of ornamental trees and shrubs are infected including Acer, Cercis , Morus, Juglans, Eleagnus and Magnolia species.

Non-chemical Control

Cut back and destroy infected branches and remove heavily affected plants. Use sharp tools when pruning, avoiding snagging the wood and use disinfectant on the blades between plants.

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

     Canker (General)

     Various Canker Species

Description

This is a fungal problem that enters the plant through wounds causing dieback of twigs and stems.

Symptoms

The stems become discoloured (pale brown) usually from a pruned point, working its way down the stem and normally intersecting or surrounded with live cambium. The bark splits or cracks, foliage dies 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.

Black Canker (Phyaslospora miyabeana) forms dark brown spots with concentric rings on the upper leaf surface and grey spots on the stems. The tiny black fruiting bodies develop in the stem lesions. It is found on Salix species and persistent attacks will kill the tree.

The Canker (Cytospora valsa) causes the browning and death of branches in Picea abies and Picea pungens. This infection occurs normally from the base of the tree with infected needles falling, and white resinous patches appearing on the bark accompanied by cankers with tiny black fruiting bodies.

The Canker (Corynneum cardinale) is a casual fungus that invades wounds and infects living bark and associated cambium turning the foliage yellowish. As it spreads it girdles the branch killing it and ultimately the top of the tree dies out. Cankers eventually form in the trunk and ooze resin. It is found on Cypress.

   Platanus x hybrida

Cankerstain (Ceratocystis fimbriata f. platani) forms sunken cankers on the trunk and large limbs forming longitudinal cracks and roughened bark. Infected areas form callus around the margins which dies off and when cut open, dark coloured streaks are revealed extending to the central pith. These streaks then radiate out into uninfected wood resulting in the thinning of the crown and producing unusual small leaves. It is normally transmitted through poor tree surgery techniques and infected tools.

Cytospora Canker

Cytospora Canker (Cytospora chrysosperma) is a casual fungus that infects the young twigs, then moving to the stems, branches and trunk causing brown sunken areas to appear that is covered in red pustules. The fungus tends to attack trees that are in poor health. Control requires the removal of infected branches and improved culture to regain the plants vigour. Sorbus aucuparia, Salix and Popular species are susceptible.

Cypress Canker

Cypress Canker (Seiridium species) enters the plant through wounds or through insect damage causes the bark to spread revealing brown powdery spores that are accompanied by oozing resin. The canker eventually girdles the branch or trunk causing ringbarking and the death of the plant.

Nectria Canker (Nectria Cinnabarina) forms cankers on the twigs and small branches producing red fruiting bodies and eventually killing the tree. It is found in many parts of the world infecting a range of trees including hardwoods.

          Populus nigra

Poplar Canker (Cryptodiaporthe populea) infects the cambium layer damaging the bark and sapwood where the elongated sunken canker forms. Branches are girdled causing the upper portion to die off. This is a serious problem for Populus nigra var. Italica entering the plant through wounds or the leaves then spreading to twigs and branches. Control is difficult as removal of infected parts will not eradicate the problem, but encourage it. Young plants may be sprayed with a copper based fungicide to reduce leaf infection and heavily infected plants should be removed the burnt.

Stem Canker of Red Flowering Gum (Sporotrichum destructor) enters through wounds in the bark forming cankers in the trunk and branches, splitting the bark apart, revealing the wood and infesting the surface with powdery spores. This infection causes the leaves to wither and then the branches die, eventually killing the tree.

Stem Canker (Strumella coryneoidea) is a casual fungus that forms on the trunks of trees as a smooth, dispersed or sunken infection. On mature trees the infection sheds the bark with the canker forming callus tissue around the margins and the centre being exposed. These cankers then tend to extend up and down the trunk, only girdling over a long period of time. It is found on Quercus, Fagus, Aesculus species, and Acer rubrum , Nyssa sylvatica, Carya ovata and Morinda citrifolia.

Source and Dispersal

The spores are found on infected dead plant material and can be dispersed by wind and with 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

Cankers may infect a wide range of trees and shrubs with some species being specific to its host. Examples are listed below.

Abies species are infected by several cankers including (Cytospora pinastri), (Cryptosporium macrospermum) and (Scoleconectria balsamea). These fungi form dead sunken areas on the trunk and branches.

Alnus species are infected by a few cankers including (Nectria coccinea) and (Physalospora obtusa) these attack the branches causing die back.

Betula species may be infected by the Canker (Nectria galligena) that occurs in the forks of trees causing splitting and cracking of the bark by swelling, to reveal the canker. Callus rings may form around the affected areas as a defence mechanism triggered by the tree.

Buxus species are infected by the Canker (Pseudonectria rousseliana) which shows signs of poor new growth during spring with the leaves turning from light green to a tan colour. These leaves tend to lay flat along the stems and reddish pustules appear both on the stems and leaves. The bark becomes loose and on inspection reveals a darkish colour underneath. It is difficult to control and the canker can kill the plant.

Castanea species are infected by the Twig Canker (Cryptodiaporthe castanea), a fungal problem that causes significant damage to the twigs and small branches, but tends to attack stressed trees.

Cercis and Ribes species are infected by the Canker (Botryosphaeria ribis) which forms small sunken areas on the stems causing wilting and eventually killing the branch by girdling. The cankers turn the bark black then split it open and the adjoining wood becomes discoloured. This is a serious problem for this and many other plant species.

Cotoneaster, Betula, Catalpa and Aesculus species are infected by the canker (Physalospora obtusa).

                  Cypress Canker

Cupressus species and Chamaecyparis lawsoniana are susceptible to Cypress Canker (Seiridium species) which causes leaf browning and then girdles the trunks resulting in ringbark. There is also another Canker (Coryneum cardinale) that has simular characteristics and is found in the northern hemisphere.

Cupressus sempervirens is infected by Cytospora Canker (Cytospora cenisia var. littoralis).

Larix species are susceptible to several fungal cankers including (Trichoscyphella wilkommii), (Trichoscyphella ellisiana), (Aleurodiscus amorphus), (Leucostoma Kunzei) and (Phomopsis spp.)

Nyssa sylvatica is attacked by three cankers including (Strumella coryneoidea).

Pinus species are infected by many types of cankers.

Platanus species are infected by Cankerstain.

Cytospora Canker on Salix babylonica

Pseudotsuga menziesii Douglas Fir is attacked by several cankers including (Cytospora species), (Dasyscypha ellisiana), (Dasyscypha pseudotsugae), (Phacidiopycnis pseudotsugae) and (Phomopsis lokoyae). These infections normally do not require control and are more prevalent on the coastal form.

Salix and Populus species are infected by several cankers including Cytospora Canker (Cytospora chrysosperma), Hypoxylon Canker (Hypoxylon pruinatum), Septoria Canker (Mycosphaerella populorum) and Branch Gall (Macrophoma tumefaciens). Many of these fungi can cause the death of the plant.

Thuja orientalis, Cupressus and Juniperus species are infected by the canker (Corynneum cardinale).

Tilia and Acer species are infected by (Nectria cinnabarina) attacking twigs or branches.

Tsuga species are infected by several cankers including (Dermatea balsamea) and ( Cytospora species).

Ulmus species are infected with up to eight fungal cankers including (Apioporthe apiospora) and (Nectria coccinea).

Vaccinium ovatum is infected by the canker (Coryneum microstictum) which attacks the stems.

Vinca species are infected by canker-dieback (Phomopsis livella) causing the shoots to wilt, turn brown and die. This can reduce the plant to ground level, and normally occurs during rainy periods.

Non-chemical Control

It is very difficult to control and correct pruning techniques with sharp tools for repairing wounds or prune well below the infected areas. Ensure that there are no ragged edges on the cuts and the angle should cut allows water to run off or dress the wound. Plant resistant varieties when available. Heavily infected trees should be removed to avoid spreading the disease.

Improve the culture of the affected plant to increase vigour for greater resistance.

Chemical Control

There is no satisfactory chemical control and prevention is imperative.

Note

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

DISEASE

   NAME

     Lichens

     Various Lichen Species

Description

A fungus and an alga growing in a symbiotic relationship.  The food producing alga is given support and shelter by the fungus.

Symptoms

Lichens are variable, occurring in many shapes, sizes and colours from flat to circular and may be leaf like crinkly or hairy.  The colour also varies from greenish grey to yellow or orange.  They occur on many surfaces including tree trunks, rocks, fences and roof tiles.  They cause little harm to living plants and certain types are attractive while others are unsightly.  

Fagus sylvatica     

Source and Dispersal

Contaminated areas, and is dispersed by wind or splashing water.

Favoured Conditions

Conditions are variable as some types prefer cool moist situations while others tolerate open exposed positions.

Affected Plants

There are many plants that form lichens on the bark, particular old woody trees that are in shaded moist positions. Shrubs and Palms also form coverage of lichens on there stems under moist conditions.

Archontophoenix cunninghamiana     

Non-chemical Control

Under normal circumstances, unnecessary but lichens can be removed by scraping or scrubbing.

Chemical Control

Not normally required but lichens can be killed by spraying the fungicide copper oxychloride but take care as the chemical may damage certain building materials.

Note

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

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.