Dry Bubble: Verticillium fungicola

Dry Bubble

• Pathogen: Verticillium fungicola
• Common Names for this disease include: Verticillium disease, brown spot, and dry bubble
• The pathogen causes considerable yield losses in cultivated mushrooms
• Artificial inoculation with the pathogen delays pinhead formation by 5 days, and reduces the number and weight of fruit bodies by 2.26-47.2% and 2.19-38.01% respectively
• Verticillium is carried to farms via infected casing soil, and spreads through infected equipment, hands, and clothing
• Sciarids and phorids transmit 84-100% and 76-100% of V. fungicola into two different media, respectively under laboratory conditions
• It also perpetuates through resting mycelium from dried bulbils and in spent compost
• Disease development is optimum at 20°C
• From infection to symptom expression takes 10 days for distortion symptoms and 3-4 days for cap spotting at 20°C
• The pathogen grows best at 24°C
• Initial Symptom: Whitish mycelial growth on the casing soil, tending to turn greyish-yellow
• Early Infection: Production of typical onion-shaped mushrooms, sometimes appearing as small undifferentiated tissue masses up to 2cm in diameter
• Later Infection: Affected mushrooms are greyish with grey mouldy fuzz
• Developed Sporophores: Localized light brown depressed spots. Adjacent spots coalesce and form irregular brown blotches
• To manage dry bubble, the following is recommended: Use sterilized casing soil and proper disposal of spent compost
• Proper hygiene and sanitation are essential to avoid primary infection
• Heat treatment of infected casing layer at 63°C for one hour completely prevented spore germination
• Spraying casing soil with 100*106 Trichoderma propagules/litre/m2 controls V.malthousei
• In laboratory conditions, leaf extracts of Callistemon lanceolatus, Cannabis sativus, Citrus sp., Euclyptus sp., Dhatura sp., and Dhatura sp. can be used as a biological control
• In laboratory trials, V.malthousei was controlled on a large scale when Bercema-Zineb 80 used at 0.1 - 1.2%
• Application of chlorothalonil as a drench reduced the incidence of V.fungicola
• Spraying with prochloraz manganese at 60g/100m2 within 7 days of casing and subsequently at 2-week intervals can achieve good control of V.fungicola -Fungicides like triadimefon (1g/m2) and prochloraz (1g/m2) are also effective

Wet Bubble

• Pathogen: Mycogone perniciosa
• Common Names include: Wet bubble, white mould, bubble, and Mycogone disease
• Wet bubble in white button mushroom incited by Mycogone perniciosa Magn, is a serious disease in major mushroom-growing countries
• Bubbles or mole (M. perniciosa), first described from Paris in 1888, is responsible for the heaviest losses in mushroom beds in France, England, and the United States
• Management of this disease has been reported to assume serious proportions in mushroom growing countries like the United Kingdom, Netherlands, USA, China, Taiwan, South Africa, Brazil, Hungary, Australia, and Poland
• In India, it was first reported in 1978 from some mushroom farms in Jammu and Kashmir
• Recognised symptom types include: infected sporophores and sclerodermoid masses
• When infection took place before the differentiation of stipe and pileus the selerodermoid form resulted
• Infection after differentiation resulted in the production of thickened stipe with deformation of the gills
• Symptoms shown are short, curly, pure-white fluffy mouldy growth of the pathogen on malformed mushrooms
• Cross section of deformed sporophores without cottony growth showed a black circular area just beneath the upper layer
• Aerated steam at 54.4°C for 15 minutes can eliminate M. perniciosa from casing soil
• Use plastic pots to cover mushroom showing wet bubble symptoms during cropping season to prevent spread
• Three methods of prevention include: steam sterilization, formaldehyde fumigation, and fungicidal application of mushroom beds
• Screening and selection of disease resistant strains can also be used
• Benomyl spray at 0.5-4g/m2 immediately after casing is effective for protecting the crop
• Carbendazim, benamyl, chlorothalonil, and prochloraz manganese complex into casing mixture have been reported very effective for management
• A spray of 0.8% formalin on to casing surface immediately after casing, but this concentration can be harmful if used at a later stage

Cob Web

• Pathogen: Cladobotryum dendroides
• Common Names: Mildew, Soft decay, Hypomyces mildew disease, Dactylium disease
• This disease causes extensive damage by soft rot, or decay of fruiting body
• Mushrooms of any age of development can be attacked
• Under artificial inoculation conditions, the loss in marketable mushrooms has been estimated
• The disease appears as small white patches on the casing soil, then spreads to the nearest mushroom by a fine grey-white mycelium
• A floccose white mycelium covers the stipe, pileus, and gills, eventually resulting in decomposition of the entire fruit body
• As infection develops, mycelium becomes pigmented, eventually turning a delicate pink cover
• In severe attacks, a dense white mould develops over casing and mushrooms, changing from a fluffy cobweb to a dense mat of mycelium
• White color can turn pink or even red with age
• A symptom that can appear, but is generally not associated with the disease, is cap spotting
• Disinfection of casing soil with live steam or sterilization of casing mixture at 50°C for 4 hours effectively eliminates the pathogen
• Regular cleaning, removal of cut mushroom stems and young half-dead mushrooms after each break, and controlling temperature and humidity helps control the disease
• Under laboratory conditions, leaf extract of Cannabis sativus, Ricinus communis, Callistemon lanceolatus, Citrus sp., Euclyptus sp., and Dhatura sp. have shown inhibition effects on C.dendroides
• Annual disinfection of houses and surrounding areas with 2% bordeaux mixture or with 5% formation solution at 0.5-1.0 l/m2, or fumigation with 2.0-2.5 l formaldehyde and 0.5-1.0 kg chlorinated lime/100 m3 can control the disease
• Best control can be obtained by applying bavistin + TMTD at 0.9 and 0.6g/m2, followed by TBZ and benlate (0.9g/m2)

Green Mould

• Pathogens: Trichoderma viride, T. hamatum, T. harzianum, T. koningii, Penicillium cyclopium, and Aspergillus spp
• Common Names: Trichoderma spot, Trichoderma blotch, Trichoderma mildew, and Green mould
• Species of Trichoderma reported as competitors and/or pathogens on button mushroom: T. viride and T. koningii
• A dense, pure white growth of mycelium may appear on the casing surface or in compost, resembling mushroom mycelium
• Later on, the mycelial mat turns green due to heavy sporulation
• The mould creeps to the surface of the casing layer and infects the new parts + developing primordia
• Mushrooms near the mycelium turn brown, may crack and distort, and the stipe peels similarly to mushrooms attacked that have dry bubble
• Preventative measures: very good hygiene, proper pasteurization/conditioning of compost, sterilizing supplements before/after spawning
• The correct concentration of formalin must be used
• Weekly sprays of mancozeb (0.2%), bavistin (0.1%), TBZ (0.2%), or treatment with zineb dust/Calcium hypochlorite (1.5%) have given effective control

False Truffle

• Pathogen: Diehliomyces microsporus
• Common Name: Truffle disease
• 1-80% natural incidence in the States of Himachal Pradesh, Haryana, Punjab, and Uttar Pradesh due to natural climatic conditions
• Limiting factor in the production of A. bitorquis in India given its higher temperature requirements
• Symptom: fluffy mycelium is white, but becomes creamy yellow
• Gradual progression: mycelial growth thickens and develops into whitish, solid, wrinkled, rounded to irregular fungal masses resembling smallbrains
• At Maturity: pink, dry, reddish color with chlorine-like odor, and compost turns dull brown + fungus growth prohibits mycelial growth
• The spawn turns soggy and disappears
• Composting should be prepared on a concrete floor
• Temperature should remain between 26-27°C
• Casing soils known to harbor traces of spores should not be used
• Harvest young before their fruit bodies turn brown
• Recommended: 70°C for 12 hours
• Thermal death point of aeciospores and mycelium has been reported to be 70°C for 1 hr. and 45°C for 30 minutes, respectively

Olive Green Mould

• Pathogen: Chaetomium olivaceum, C. globosum
• First occurrence in India was noted in 1975
• Yield losses ranging from 12.8-53.65% can occur
• Fungus signs consist of inconspicuous greyish-white fine mycelium in the compost, or fine aerial growth on the compost surface ~10 days after spawning
• Spawn may be delayed/reduced
• Cockle-burns-1/16 inch in diameter may arise and the compost can smell musty
• Normal spawn growth is often delayed
• C. globosum is seen on spawn bottles
• Compost fermentation should be long
• Should provide active compost that is not too wet and has a good structure
• Do not add nitrogen, ammonium sulphate, urea, chicken manure, or similar materials before filling
• There should be sufficient time for peak-heating and a sufficient supply of fresh air during pasteurization
• Higher temperatures during pasteurization should be avoided
• Fungicides including Benomyl, Thiophanate methyl, TBZ, Vitavax, Dithane Z-78, Dithane M-45, Thiram and Captan

Brown Plaster Mould

• Pathogen: Papulaspora byssina Hots
• Often located across most mushroom farms in India
• This strain appears when the spawn is running
• Has been isolated from compost and casing located in mushroom farms in Northern India
• Incidence rates are near 5 to 9%
• Whitish mycelial growth on the exposed surface
• The surface in trays, as well as the sides of bags are often condensed
• Progresses to large, dense patches as color lightens from tan, to brown, to cinnamon color
• No mushroom mycelium can grow where plaster mold is
• Composting should be done carefully
• Can use sufficient gypsum and not too much water
• Peak heating has to be of a sufficient duration and be at proper temperatures
• Spraying of systemic fungicides at 0.1% concentration should also be administered

Lipstick Mould

• Pathogen: Sporendonema purpurescens
• Common names: Lipstick, Red lipstick
• Reported in certain mushroom farms in Punjab and Himachal Pradesh
• Initial sign is spawned compost containing crystalline mould
• Matures to pink, cherry red, and orange colour
• High mycelial growth in loose casing areas
• Crops that also contain viruses are very prone to secondary growth
• Primary inoculum can come from soil
• Often primary dissemination comes from water
• Most often caused by chicken manure
• Very effective to maintain high hygiene, pasteurization, and proper conditioning of the compost

Yellow Mould

• Pathogen: Myceliophthora lutea, Chrysosporium luteum, C. sulphureum
• Fungi produce yellow mycelial growth in the compost
• The molds may stay below the surface
• Can also form circular colonies or may be distributed throughout
• Can disrupt casing and also impede spawn
• Stromas develop and severely inhibit mushroom production
• Sources of initial inoculum
• Other types stem from chicken manure
• Fungus easily survives through thick-walled bodies
• Typically thrive in moist environments and mild temperatures
• Pasteurization can limit risk
• Benomyl spray can be used
• Calcium sprays can also remove mold

Ink Caps

• Pathogen: Coprinus spp.
• Common name: Ink weed, wild mushrooms
• The appearance of inky caps during spawn run is commonly observed in mushroom beds in northern India.
• Ink caps also appear in the compost. It may also appear outside manure piles during fermentation
• Slender, bell-shaped mushrooms.
• Usually cream colored initially, then blueish-black afterward
• Grow in clusters and possess long, sturdy stems
• Decay and form blackish slimy mass because the fungus autotdigests
• Capsule widths are between 1.5 to 4 cm
• Early development begins in oval, and later develops into conical, white scales.
• The decaying caps form an umbrella.
• Primary factor to get infections is through the compost
• Nitrogen from chicken manure can facilitate the formation of caps
• Lack of nutrients and low temperature allow ink caps to thrive
• Pasteurization and control of the soil are advised