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 sporangiaor pycnidiaor 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 reginaeflower
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 Rosaspecies 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 speciesand 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 Castaneaspecies, 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 ofUlmusspecies 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)isa 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(Curvulariaspecies) 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 Ringsare a fungal problem in Turf Grassand is caused by several species including (Lycoperdonspecies), (Marasmius species) and (Tricholomaspecies). 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 Quercusspecies..
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 Aesculusspecies
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 Grevilleaand Hakeaspecies 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, Festucaand Agrostisspecies.
Pad decay (Aspergilus alliaceus) infects Cereusand Opuntiaspecies 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 Holeis 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 Ranunculusspecies, it also infects cactus speciesby 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(Leptosphaerispecies) 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 Cactusspecies entering through the stomates or wounds. Heavily infected plants collapse and die.
Stem Rotor 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 Quercusspecies and other ornamental trees.
Witches Broommay 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, Leptospermumand Pinusspecies.
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 Necrosisis found in Liquidambarspecies and Stem Rot or Dry Rot infects Cactus species such as Opuntia and Pelargonium.
Abiesspecies are infected by several fungi that cause Leaf Castwhich turn the needles yellow to brown then fall prematurely.
Abutilonspecies 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.
Aglaonema species are infected by Root Rot(Pythium spp.). Symptoms include the roots turning black and mushy resulting in the wilting of plant and yellowing of the lower leaves. Control methods include using pathogen free stock for propagation and drenching soils in with the appropriate fungicide.
Alternantheraspecies 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, Kalanchoeand Schlumbergereraspecies are infected by Bipolaris Stem Rot(Bipolaris cactivora). This infection affects many cacti species causing rot in the stems with a blackish appearance.
Amelanchleris affected by the Witches Broom(Apiosporina collinsii).
Antirrhinumspecies 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.
Begoniaspecies 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.
Betulaspecies are affected by the Leaf Blister (Taphrina bacteriosperma) which curls the leaves and forms reddish blisters.
Chamaedoreaand 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.
Crocusand Gladiolusspecies are infected by the Dry Rot(Stromatinia gladioli), which causes lesions on the corms and rots the leaf sheath.
Crocus, Iris, Tulipa, and Narcissusspecies are infected Copper Web((Rhizoctonia crocorum).
Dianthusspecies 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 sykesiimay be infected by the Root Rot Fungi(Phymatotrichum omnivorum).
Fernspecies 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.
Forsythiaspecies are infected by Stem Gall (Phomopsisspecies). It forms rounded growths along the stems causing them to die and look unsightly.
Gladiolusspecies are infected by Penicillium Rotof 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 Spotsincluding (Glomerella cingulate), (Phyllosticta concentrica) and (Ramularia hedericola). All of which cause yellowish spots that develop into dry brown blotches that kill the leaf.
Larixspecies 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.
Orchidssuch as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalumspecies are infected by Phomopsis Rot(Phomopsisspecies). 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 coloratusimplicated). Dark spots appear on the pseudobulbs eventually causing extensive rot and killing the bulb.
Palmsare 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, Echinopsand Orchid species are infected by the