Mushroom Culture

Diseases and mould problems in mushroom cultivation and their management (Contd..)

4) WHITE PLASTER MOULD:

• The mould appears as white patches in between or on the compost surface during spawn run stage or also in the casing layer . It inhibits the growth of mushroom mycelium causing yield loss to the extent of 5 – 30 per cent.

Causal Organism:

• Scopulariopsis fimicola is the fungus responsible for the contamination.

Favourable factors:

• Under or over -composted conditions having high pH (above 8.0) favour the growth of this mould .

Control methods:

• Mixing of compost ingredients in recommended quantities, proper wetting and turning of compost under hygienic conditions have been highly recommended . Removal of mould from the compost layer and spray of benomyl or carbendazim ( 0.05 % ) are recommended for its control . In case of high pH and moisture content of compost, delayed turning or conditioning and addition of gypsum is recommended.
• 
  

Fig. 13.14 & 13.15 shows: (a) Patches of white plaster mould in compost bed, (b) the conidiophore and conidial spores of Scopulariopsis fimicola

5) INKCAP OR COPRINUS:

• Long stemmed mushrooms with small caps are often seen coming out of the compost which soon turn black , collapse and get decomposed.

Fig. 13.16 to 13.18 Inky Cap weed, Fig. 13.19 & 13.20 shows: Appearance of fruit bodies of Coprinus spp.as weed fungi or competitor moulds in compost and straw beds during mushroom cultivation process

Causal Organism:

• Several species of Coprinus like Coprinus comatus , C. logopus , C. atramentarius , C. fimetorius etc; have been observed appearing in mushroom beds .

Favourable Factors:

• Coprinus spores generally enter through compost ingredients, chicken manure, improperly pasteurized compost, casing material and also through air. Their appearance indicates ammonia still present in the compost, a sign of improper pasteurization and turning or higher quantity of nitrogenous materials, including chicken manure added to the compost .

Control measures:

• Maintenance of hygienic conditions, mixing of quality ingredients while preparing compost at proper ratio, proper turning and pasteurization of compost is necessary Addition of too much nitrogenous material and water should be avoided.

6) YELLOW MOULD ( CONFETTI , VERT-DE-GRIS , MAT DISEASE ):

• Since a number of fungi produce yellow mycelial growth in the compost ( yellow Mould ) or beneath the compost in the form of yellow layer ( mat ) or in the form of circular colonies ( confetti ) or distributed all over the compost ( Vert – de – gris ) , these are known by different names .

Causal Organism:

• The mycelium of Chrysosporium luteum is white at the initial stage that turns yellow to dark tan with dull white sporulation .
• 
  

Fig. 13.21 & 13.22 shows: (a) Occurrence of mat disease in mushroom bed, (b) the mycelial structure of fungus Chrysosporium sp. with conidiophores and spores

Epidemiology:

• The sources of inoculum are mainly the compost ingredients, chicken manure, air, spent compost and wooden trays . It further spreads through workers’ hands or clothes, mushroom flies, mites, faulty technique of water spray ( splash ) and the picking tools .

Control measures:

• Proper hygiene, removal and burial of mould affected spent compost at a distant place, proper turning and pasteurization of the compost and casing mixture, use of light and misty water spray technique, covering the windows and ventilators with fine wiremesh, use of filtered air and spray of Benomyl ( 400- 500 ppm ) and Blitox ( 0.25 % ) have been found effective in controlling the disease.

7) SEPEDONIUM YELLOW MOULD:

• This mould is found growing in between the compost layer or at the bottom layer. The fungus is initially white but turns yellow or tan coloured at maturity .
• 
  

Fig. 23 & 13.24 shows: (a) Mushroom beds infected with Sepedonium yellow mould, (b) the microscopic structure of Sepedonium sp producing two types of conidia

Causal Organism:

• Sepedonium chrysospermum Bull ( Fries ) and S. maheshwarianum Muker. have been found mainly responsible for the occurrence of the mould .

Epidemiology:

• Spent compost, soil , air, improperly pasteurized compost / casing soil, wooden trays etc; are the primary sources of inoculum as the thick walled chlamydospores are resistant to peak heat temperature, if not pasteurized properly. The compost prepared by long method of composting have more chances to have this mould.

Control methods:

• Strict hygiene followed by proper pasteurization of compost at 59 – 60 º C for minimum four hours is recommended. Use of filtered air with high efficiency filters in the cropping rooms and cook out of compost at the end of the crop with steam at 70 º C for 10 – 12 hours are recommended. Sterilization of chicken manure with 2 % formalin and 0.5 % Carbendazim prior to composting has been found to give good result ( Vijay et al ,1993 ).

8) FALSE TRUFFLE:

• It is the most serious competitor mould found during A bisporus cultivation apart from its appearance in A.bitorquis beds. It is commonly found occurring in compost prepared by long method of composting , especially during summer months .

Symptoms:

• The mycelial colour is initially white at the start and hence difficult to differentiate with the growth of the mushroom mycelium, but soon turns creamy yellow at later stage . It appears as small, wefts of white cream coloured mycelium in compost and casing soil, mainly below the casing. The mycelium becomes thick and develops into whitish, solid , round toirregular, wrinkled fungal masses resembling calve’s brain which are the ascocarps of the fungus.
• 
  

Fig. 13.25 & 13.26 shows: The calve’s brain shaped ascocarps of Diehliomyces microsporus, the false truffle fungus

Causal Organism:

• The ascocarps of Diehliomyces microsporus are fleshy white initially which turn brown and reddish brown at a later stage.

Epidemiology:

• The fungus enters the cropping room through spent compost, chicken manure, casing material, old infected wooden trays and already infected rooms as the ascocarps can survive for a period of five years in soil and spent compost and for six months in the form of mycelium.

Control methods:

• The compost should never come in contact with the soil, hence it is always better to have a cemented composting yard , covered with a roof with slight gradient. Proper pasteurization of compost ( 59 º C for 3-4 hours ), systematic turning and conditioning is very much essential for complete elimination of the fungus. The casing soil should be sterilized at 65±1º C for 6-8 hours. The bed temperature during spawn run and cropping should be maintained below 18 º C as it is a very critical situation . Cook out at 70 º C for 10-12 hours will eradicate the fungus as the thermal death point of the fungus has been reported to be 70 º C for 1 hour (ascospore )and 45 º C for 30 minutes ( mycelium ) .

9) LIPSTICK MOULD ( Sporendonema purpurescens ):

• The mould is noticed as pink mycelial growth on the casing at several crackings or in loose areas of casing . Because of its pink coloured spores, it is known as Lipstick mould . It first appears as a white crystalline mould not differing from white mushroom mycelium in the spawned compost.

Fig. 13.27 & 13.28 shows: The mycelium , conidiophores and conidia of S. purpurescens

Epidemiology:

• The fungus enters mainly through soil, casing material and spent compost which is further disseminated through splashed water sprays and contact with workers’ hands.

Control methods:

• Proper hygiene and pasteurization of compost at proper temperature eliminates the fungus.

10) OEDOCEPHALUM MOULD (Oedocephalum fimetorium , O. spp. ):

• The mould appears as irregular, light silver grey patches on the compost surface during conditioning and at the time of filling or spawning . During spawn run the mould appears light grey in colour which soon changes to dark tan or light brown with the maturation of spores . It also appears on the casing surface .

Control methods:

• Hygienic measures and proper pasteurization of compost has been found to eliminate the mould .

11) CINNAMON MOULD (Chromelosporium fulva , Ostracoderma fulva, C . ollare with their perfect stage as Peziza ostracoderma):

• Due to its cinnamon brown colour in the compost or casing layers in the form of circular white mycelial patches, it is known as Cinnamon Brown Mould. It appears as circular white patches of white mycelium which changes its colour to light brown, then light golden brown and ultimately to cinnamon with granular appearance.

Control methods:

• Proper hygiene and sterilization of casing avoiding bed temperature above 65 ºC, proper composting and pasteurization will eliminate the fungus. Dithane Z-78 and Dithane M-45 sprays (0.2 %) have also been found to control the mould .