Agriculture: IMPORTANCE OF MUSHROOMS, PEST AND DISEASES IN MUSHROOM CULTIVATION AND THEIR MANAGEMENT

IMPORTANCE OF MUSHROOMS, PEST AND DISEASES IN MUSHROOM CULTIVATION AND THEIR MANAGEMENT

Mushroom is a form of plant life knows as fungus. Mushroom can be defined as a saprophytic macro fungus with a distinctive fruiting body. They grow wild in almost all type of soils, on decaying matter and wooden stumps etc.

It has been estimated that out of 10000 species of flashy fungi about half of them are edible and as many as 100 species are poisonous. About 2000 species from more than 30 genera recorded as prime edible mushroom but only about 50 of them are grown experimentally, 40 cultivated economically, 20 cultivated experimentally, about 4-5 are industrial scale.

Types of mushrooms

S.No	Name of the mushroom	Scientific name	Temperature	Relative humidity
1	Paddy straw mushroom	Volvariealla volvaceae	28-35ºC	80-95%	April-sept.
2	White button mushroom	Agaricus bisporus	14-16 ºC	90-95%	Sept-jan.
3	Oyster mushroom	Pleurotus florida	24-28 ºC	80-85%	Oct-feb.
4	Elm oyster mushroom	Hipsizygne almarius	25-28 ºC	75-85%	July-Feb.
5	Milky mushroom	Calocybe indica	30-35 ºC	80-95%	March-oct.

IMPORTANCE OF MUSHROOM CULTIVATION

1. Mushrooms are known as vegetable meat and form a good supplement for protein diet.

2. Analysis of some common edible mushroom showed that they contains 89-91% water, 0.97-1.26% ash, 2.78-3.94% protein, 0.25-0.65% fat, 0.09-1.67% crude fibre, 5.3-6.28% carbohydrates and energy value of 24.4-34.4 Kcal. Being free from fat and starch they serve as good diet for diabetics and obesity persons.

3. They have high percentage of all nine essential amino acids and very high in lysine and tryptophan, the two amino acids deficits in cereals.

4. Mushrooms are almost free from fat except for linoleic acid and are richer than most vegetables in water soluble vitamins (B1, B2, Niacin, B12, and Pantothenic acid)

5. They are good source of minerals i.e. P K Ca Cu and Na. They are low in calories (less than 30g/100g) with very less traces of sugar and no cholesterol.

PESTS AND DISEASES OF MUSHROOM AND THEIR MANAGEMENT

Bacteria, fungi, nematodes, mites and insects are most commonly encountered biotic causes of disorders. The involved organisms/cause should be correctly identified before attempting to control the problem. It’s essential to understand the biology of the organism, wherever involved (how it gained entry, how its spread, how it can control) and after this, a suitable method of controlling the pest or pathogen should be devised. Basically farm hygiene is the best approach to the control of mushroom disorders.

The incidence and severity of the pest problem are directly related to the degree of control of the growing environment. The available technology of air conditioning, air movement, humidification, air filtration, insulation and post-harvest storage have mad pest management much easier. The availability to preciously control the production environment can lead to the production of pest-free pesticide-free and high quality mushroom at reasonable cost.

FUNGAL DISEASES

(A) DRY BUBBLE

Causal organism- Verticillium fungicola

Dry bubble disease of mushroom

SYMPTOMS

· Whitish mycelial growth appear on the cashing soil which turn greyish yellow. If infection take place in an early (pin head stage), the typical onion shaped mushroom are produced.

· The stem is thicker than the cap, which is often not distinguishable from the stem.

· At the later stages of infection crooked and deformed mushroom can be seen.

· When a part of the cap is affected hare-lip symptoms is noticed. The affected mushroom turn greyish.

CONTROL

· Use of sterilized casing soil, proper dispose of spent compost, control of insects/nematodes/mites and better hygiene are essential to avoid primary infection.

· Spraying with Dithane Z-78, Sporgon at 1.5g/m² nine days after casing, Topsin M, Chlorothalonil, Prochloraz and Daconil are effective in checking dry bubble.

· Control local infection by spraying the affected patch with 2% commercial formalin.

· Dry bubble can be managed effectively by adopting strict hygienic measures, using properly pasteurized compost and sterilized casing mixtures and maintaining ideal environmental condition.

(B) COBWEB DISEASE

Causal organism- Clodobotryum dendroides

Cobweb disease of mushroom

SYMPTOMS

· Small circular, white patches of the mycelium are first seen on the surface of the casing.

· As the disease progresses, a fluffy white mould grows over the mushroom. Eventually mushroom effected by cobweb disease turn brown, being to rot and die off.

· In severe attacks a dense white mould develops over casing and mushroom change from a fluffy cobweb to dense mat of mycelium. The white colour can turn pink or red with age.

CONTROL

· Thoroughly disinfect the casing soil with live steam or formaldehyde and/or treat with 150g Benomyl per 100m² upon casing.

· Sterilizing the casing mixture even at 50ºC for 4 hours can kill the pathogen.

· Clean the beds on schedule, remove the stem of cut mushrooms and young half dead mushroom.

· Temperature and humidity during picking should not go beyond 60ºF and 90% respectively.

· Fungicides can be applied to the surface of casing, Benzimidazole and prochloraz manganese and chlorothalonil can be applied in the initial casing mixture or spread on between flushes.

· Use of Bavistin+TMTD at g/m² is better. Dust between flushes with zineb or mancozeb, 100 g/m² once in a week or spray the beds with a weak solution of formalin (0.2%-0.3%).

· Treat the small spots of cobweb mould immediately with salt or formaldehyde.

· When the room has not been cooked out, water the beds immediately upon emptying to prevent spreading of spores.

(C) WET BUBBLE DISEASE

Causal organism- Mycogone perniciosa

WET BUBBLE DISEASE

SYMPTOMS

Young pinheads develops monstrous shaped which often don’t even resembles mushroom. The short, curly, pure white fluffy mould of mycogene can easily be observed on and around the infected mushroom. The colour of infected area becomes greenish brown due to the formation of dark colour chlamydospores. Clear, brown coloured drops caused by putrefying bacteria exude from the bubble. At this stage, bubble is weak or completely rotten and emits unpleasant odour.

CONTROL

· Good hygiene, use of properly sterilized casing soil and spraying with Diathane Z-78 (0.3%) at weekly interval provide good control.

Typical Onion Shaped Mushroom Symptoms of Dry Bubble

Thickened Stipe: Wet Bubble Infection

(D) GREEN MOULD

Causal organism- Trichoderma sp.

SYMPTOMS

Green mould disease

Different species of Trichoderma occurring in compost, on casing soil in the span bottles and on grains after spawning. Fruiting bodies produce dark brown on greenish lesions/spots discolouration on the pileus as well as the stipe. Trichoderma viridae produce reddish brown discolouration along the stipe by killing the tissue. Sunken, non-coalescing lesions are also produce on the pileus. Trichoderma koningii grow as cottony web causing wet rot. It also produces superficial purple brown spot with a dry cracked surface. The wefts remains grayish for a long time and sporulation is slower. The lose sage green clusters of spore heads develop on affected tissue of mushroom. The infection also start on dead tissue of mushroom that remains on the compost after harvesting. The effected caps turn brown on one side and discoloured areas are not depressed or sunken. Trichoderma hamatum is frequently seen growing during spawn run but it also causes brownish spots on mushroom caps under high humidity. On young pinheads, spots are enlarged and cracking of caps become more conspicuous. The lesions, in later stages extends to stipe also. A number of species of Penicillium including P.cyclopium or generally encountered in the compost straw heaps, grain spawn and casing soil.

CONTROL

· Green mould can be prevented by good hygiene, proper pasteurization and conditioning of compost, sterilizing the supplements before use and mixing them thoroughly after spawn run, using the correct concentration of formalin (max.2%) and weekly spray with diathan Z-78 (0.2%) or bavistin (0.1%), TBZ (0.2%) or treatment with Zineb or calcium hypo chloride (15%).

COMPETETORE MOULDS / INDICATOR MOULDS / WEED MOULDS

(1) FALSE TRUFFLE- TRUFFLE DISEASE

Whitish, solid, wrinkled and rounded to irregular fungal masses of false truffle

Truffle

Causal organism- Diehiliomyces microsporus

It is the limiting factor in the cultivation of A.bitorquis in our country. In A.bisporus sps, it is mostly noticed during late February or early march in the plains of northern India in the winter crop. The white colour of the mycelium turns creamy yellow at a later stage. It appears as small wefts of cream coloured mycelium in compost and casing soil, usually more conspicuous in the layer where compost and casing mixture meet and also on casing gradually, the mycelium growth becomes whitish, solid, wrinkled, round, to irregular fungal masses resembling small brains at maturity, these turn pink, dry and reddish and finally disintegrate in to powdery mass emitting a chlorine like odour. The fungus does not allow the mycelium to grow and compost turn dull brown the spawn in affected patches turns soggy and disappear

CONTROL

· Compost should be prepared on a concrete floor and never on uncovered soil.

· Pasteurization and conditioning of the compost should be carried out carefully.

· Temperature be not allowed to rise above 26-27⁰C during spawn run and after casing.

· During cropping temperature should be kept below 18⁰C.

· Casing soils known to harbour traces of spares should not be used.

· Young truffles must be picked and buried before the fruit bodies turn brown and spares are ripe.

· Wood work, trays or side boards of shelf beds should be treated with a solution of sodium pentachlorophenolate at the end of the crop.

· Effective cooking out kills mycelium and spores of the pathogen in the compost.

· In the initial stages treat the affected patches with formaldehyde (2%) solution

(2) OLIVE GREEN MOULD:

Causal organism - Chaetomium olivaceum and C.globasum

Olive green mould

SYMPTOMS:

An inconspicuous greyish white fine mycelium appears and become visible on the surface 10 days after spawning. Initial spawn growth is delayed and reduced, fruiting structures that took like green cockle burns. 1/16 inch in diameter, develop on straw in isolated spots of the affected compost. The compost develops musty occurs. C.globossum is also noticed on spawn bottles.

CONTROL:

· The fermentation period of the compost should not be too short.

· The compost should be active, not too wet and with a good structure.

· Nitrogen, Ammonium sulphate, Urea, Chicken manures or similar materials should not be added just before filling.

· There should be sufficient time for peak heating and sufficient supply of fresh air during pasteurisation.

· Higher temperatures for longer time should be avoided.

· Benomyl, Thiophenate methyl, TBZ, Vitavex, dithane z-78, dithane M-45, Thiram, and captan are effective under in vitro conditions.

· Dithane Z-78 checks the secondary spread.

(3) BROWN PLASTER MOULD

Causal organism: Papulospora byssina

SYMPTOMS:

Brown plater mould

Brown plaster mould causes around 90% yield loss in A. bisporus and complete crop failures of oyster mushroom. Incidence of the disease has been recorded from 20-80%. It appears as whitish growth on the exposed surface of compost and casing soil in trays as well as on sides in bags due to moisture condensation. This develop further into large dense patches gradually changing colour through shades of tan, light brown to cinnamon brown, ultimately becoming rust coloured. No mushroom mycelium grows on places where plaster mould occurs.

CONTROL:

· Strict hygienic measures should be followed.

· Composting should be done carefully, using sufficient gypsum and not too much water.

· Peak heating should be of sufficient duration and at proper temperatures.

· The compost should not be too wet before or after peak heating.

· Localised treatment of infected patches with 2-4% formalin is cc

· Spraying of systemic fungicides like benomyl, carbendazim, Thiophante methyl and vitavex at 0.1% concentration is also effective.

4) YELLOW MOULD (Mat-Disease or Vert-De-Gris).

Causal Organism: Myceliophthora lutea

Yellow Mould

SYMPTOM:

The yellow moulds may develop in a layer below the casing (mat disease), from circular in the compost (confetti) or they may be distributed throughout the compost. M.lutea forms a yellow brown corky mycelial layer at the interphase of compost and casing, which is difficult to detect during the impregnation of casing layer by the spawn and even during the first break.

CONTROL:

· Proper pasteurization of the casing mixture is very essential.

· Fungus is killed at the exposures for 6hrs at 51⁰C or 4hrs at 54⁰C.

Benomyl (400-500ppm) and blitox (400ppm) sprays are effective.

· Spraying with calcium hypochlorite solution (15%) is also effective.

5) SEPEDONIUM YELLOW MOULD:

Causal organism: Sepedonium spp.

Sepedonium Yellow Mould

SYMPTOMS:

This mould in the compost is initially white in colour turning to yellow or tan at maturity. It is generally present in the lower layers of the compost or at the bottom of the cropping bags. Various types of distortion in fruiting bodies are commonly observed. The toxins inhibit the spawn-run and ultimately mushroom mycelium disappears from the compost.

CONTROL:

· Strict temperature monitoring and control during compost pasteurization and an adequate post-crop cooking out are essential to eliminate the infestation.

· High efficiency air fillers should be installed.

· Incorporation of 0.5% carbendazim in compost and sterilizing the chicken manure with 2% formalin or 0.5% carbendazim is useful.

(6) INK CAPS, INK WEED/WILD MUSHROOM :

Causal organism : Caprinus spp

SYMPTOMS :

Ink cap appear in the compost during spawn-run or newly raised beds and outer surfaces of the compost piles during fermentation. They are slender, bell shaped mushroom, cream coloured at first, bluish black later and are usually covered with scales. Ink caps finally decay and form a blackish slimy mass due to autodigestion.

Ink Caps

CONTROL:

· Use properly pasteurised compost and casing soil.

· Avoid excessive watering, rogue out young fruit bodies of the weed.

(7) PINK MOULD

Causal organism: Cephalothecium roseum

SYMPTOM:

This mould has been observed as a white growth on the casing soil which turns pink in due course. Infection generally comes through air

Pink mould

CONTROL:

· Mould can be checked by spraying twice with thiram or captan (0.04%) on casing soil at 10 days interval.

(8) WHITE PLASTER MOULD:

Causal organism: Scopulariopsis fumicola

WHITE PLASTER MOULD

SYMPTOM:

This disease appears as white patches on the compost or casing soil. The patches or mycelium mats may be more than 50cm under favourable conditions. The white growth changes to light pink after a week of the formation of the spot. Spawn-run is reduced significantly. The pathogen is favoured by under or over composted compost which still remains the smell of ammonia and pH more than 8.0

CONTROL:

· Proper composting and addition of optimum quantities of water and gypsum are recommended.

· Sprays of benomyl (0.1%) and local application of formalin (4%) after the removal of mat are helpful.

9) LIPSTICK MOULD

Pathogen: Sporendonema purpurescens

SYMPTOM:

Lipstick mould

The disease first appears in spawned compost as a white crystalline-like mould, rather nondiscernable from spawn. As the spore of the mould mature, the colour changes from white to pink, to cherry red and then to dull orange or buff. White mycelial growth is more in loose areas of casing and can colonize well-conditioned compost. In crops where there is a serious virus disease, lipstick mould usually occurs as a secondary disease.

CONTROL:

Good hygiene is essential. Good pasteurization and conditioning of the compost will eliminate the pathogen.

BACTERIAL DISEASES

In India, bacterial diseases have been reported on A.bisporus, Pleurotus spp, and volvariella sp only.

On white button mushroom, only bacterial blotch is important in India.

(1) BACTERIAL BLOTCH, BROWN BLOTCH OR BACTERIAL SPOT :

Causal organism: Pseudomonas fluorescens

SYMPTOM:

· The pathogen induces lesions on mushroom tissues that are pale yellow initially but became golden yellow or chocolate brown later

· Blotches generally appear when mushrooms are in the early button stage, but can appear on mushroom at any growth stage.

· The spots enlarge and coalesce, sometimes covering the entire mushroom cap.

Brown Blotch or Bacterial Spot

CONTROL

· Spraying of chlorine solution (0.015%) at 0.5 litre/m²along with environmental control gives of bacterial blotch.

· Application of tetramycin at 9mg/sq foot, streptomycin (200) oxytetracycline(300).

· Pasteurization of casing soils by steam/air mixture and short wave length irradiation have been reported effective in eliminating the bacterial pathogen.

· Overheating should be avoided otherwise successive invasion of moulds would be very high.

VIRAL DISEASES

The various early names coined for mushroom virus disease give some indication of the diversity and variation of symptoms caused by viral infection. The symptoms, which have frequently been described may be expressed individually or in various combinations and in a wide range of severity. The symptoms of virus disease vary from reduced yield to distorted mushrooms.

The full range of symptoms that are encountered in non-hybrid mushrooms are also seen in hybrid mushrooms. In extreme cases all sporophore initiation is inhibited and the vigour of the mycelium is severely reduced while in other cases it is difficult to detect these symptoms.

The general symptoms observed are as below:

1. Mycelium does not permeate or hardly permeates the casing layer or disappears after the normal spread. Mushrooms appear only in dense clusters, maturing too early.

2. Mycelium isolated from diseased sporophores on agar shows a slow and degenerated growth as compared with healthy mycelium.

3. The delayed appearance of the pinheads of the first flush can be an important indication of the disease as well as the formation of fruiting primordia below the surface of the casing layer.

4. Symptoms of sporophores are highly variable. The following abnormalities can be found separately or in combination:

a) Slow mycelial growth, development of abnormal mushrooms.

b) Slow development of pinheads, dwarfing.

c) Delay in appearance of sporophores, reduced yield.

d) Off-white colour of the cap and early maturity.

e) Sporophores with elongated stems and small caps.

f) Elongated slightly bent stipes, sometimes with small early maturing pileus.

g) Premature opening of veil.

h) Mushrooms are loosely attached to the substrate and at the slightest touch are pushed over.

i) Accelerated post-harvested deterioration.

j) Watery stipes, streaking in the stipes.

k) Stipes are spongy and quickly turn brown on cutting and show an abnormal structure.

l) Thickened barrel-shaped stipes; the veil is attached to the thickest part of the stipe, thus lower than usually. Pilei are small and fat.

m) Brown, slimy, cap occur owing to a secondary bacterial rot, stipes are sometimes tapering. Downwards during the first flush, sometimes a few light brown caps can be observed.

n) Veils abnormal or absent, hard gills are common.

5) A specific musty smell can be perceived in a growing room infested with the disease. Whereas in Pleurotus, virus infection causes dwarfing or elongation of stipe. However, no distinct symptoms.

MANAGEMENT OF MUSHROOM VIRUSES

For adopting suitable management strategies for mushroom viruses, one has to keep in mind that the disease is spread by viable mycelium and spores of diseased mushrooms; early infection is dangerous, especially an infection simultaneous with or shortly after spawning. Up to the time of casing, the compost and mycelium must be protected. Owing to the lack of useful resistance with the species, control of the disease is based largely on the use of hygienic practices directed at the elimination of diseased mycelium and basidiospores from the production. Dieleman has suggested various approaches to reduce the spread of mushroom virus diseases which have been summarized below:

When the disease is not present –

1. Steam the compost for 12 hours at a temperature of 70°C. At emptying, remove the compost quickly.

2. Spray the wood with 2 per cent sodium pentachlorophenate to which 0.5-1.0 per cent soda (Sodium carbonate) has been added, after drying spray with water.

3. Disinfect doors, little holes in the floor, shutters, racks, floors and walls with formaldehyde (not with sodium pentachlorophenate). Also clean the manure yard and adjacent patches of ground with formaldehyde.

4. Before filling, fit spore filters, during growing time these spore filters should be replaced once or twice according to the amount of dust in the air. Use a fan for extracting air.

5. Immediately after spawning, use a pesticide against flies and cover the compost with paper. Keep the paper moist. Wet the paper twice a week with a 2 per cent solution of the 40 per cent commercial formaldehyde. Repeat till a few days before casing. Never use sodium pentachlorophenate here. Moisten the paper before removing it carefully.

6. Quickly remove cuttings and litter and destroy.

7. The entire farm and its surroundings should be maintained very clean and stay so. In the working corridor formaldehyde should be sprayed. Machines, refrigerator and other utilities should be disinfected with a formaldehyde solution.

8. At the first sight of contamination, the disease can be controlled best by immediately steaming out the concerned room.

When the disease is already present

1. Immerse the wood in a 4 per cent Sodium Pentachlorophenate solution to which 0.5-1 per cent sodium carbonate has been added.

2. Pick the mushrooms when still closed.

3. Keep each room as a separate entity with separate clothes, shoes, steps, buckets, picking knives, picking racks, fans etc. Kill off diseased patches with salt and cover with plastic, make the limits of the patches rather big. First pick from the healthy parts then from the diseased patches. Wash hands often.

4. Admit as few visitors in the diseased rooms as possible and keep the door towards the working corridors closed. Kill off pests in particular. Have a short picking period only (not more than 4 weeks).

Heat Therapy

When infected cultures were grown at 33ºC for 2 weeks, and hyphal tips then sub cultured and returned to 25ºC, many of the latter showed normal growth and did not contain virus.

Spawn Strains

Immunity to the virus disease of the cultivated mushroom, A.bisporus has been found in several strains of the white mushroom, A.bitorquis, collected from nature. Some strains of A.bisporus do not show symptoms as markedly as others. These are the brown, cream and off-white strains, or some smooth-white strains known to anastomose less frequently with others, or A.bitorquis can help to reduce the general virus inoculum and can enable economically worthwhile crops to be grown. Hybrid strains can anastomose with both white and off-white strains and therefore, their widespread culture may reduce the effectiveness of strain alteration as a means of virus control.

MUSHROOM PESTS

Mushroom are grown on a continuous cycle throughout the year, in a protected environment of warm, constant temperatures and high

Humidity.

When a potential pest is first noticed, it is extremely important to identify it correctly as control regimes for the various pests differ in enough aspects to cause control facilities if a misidentification occurs.

INSECT PESTS

1. SCIARIDS : (Lycoriella solani and L.auripila)

SYMPTOMS :

Mushroom flies

These are able to affect all stages of pest. Peak mushroom production. Larvae is tunnelling in the stipes, as the presence of tunnels in a cut mushroom, serious damage in economic terms, is the attack by larvae on the developing pinheads and buttons. Hence pin head/button can be hollowed out. Adult flies are capable of spreading the spores of verticillium. They will, if not controlled also act as a source of re-infestation for new crop.

CONTROL:

Access of sciarid adults to peak heat and spawn running rooms, must be prevented with the use of screening on ventilation ducts and efficient ceiling around doors. Where resistance to organophosphorus can be mixed into compost at spawning. Casing material should be treated with diflubenzuron to kill the larvae.

Diflubenzuron can also use as a post casing drench use sticky traps to monitor flies in the spawn running. Use effective screening of ventilation ducts, in the peak heat and spawn running room. Use knock down sprays during the first week spawn run and the first week of spawn run and the first week after the casing. Incorporate diflubenzuron in the casing.

2) PHORIDS: (Megaselia halterata)

Phorid fly (Megaselia halterata) on a mushroom cap

M.halterata larvae feeds only on mushroom mycelium and consequently able to cause reduction in the yield. The fields are normally most numerous in summer and late autumn.

They are also vectors of verticilium by acting as vectors flies pose a greater threat to the mushroom crop.

CONTROL :

· Dichlorovos is useful chemical as it has both contact and volatile action on flies.

· To kill larvae and compost diazinon (or) chloropyriphos must be incorporated at spawning.

· Care should be taken to keep the insecticides and spawn a part as far as possible during spawning process.

3) CECIDS:

Cecids fly

6 Species of cecid have been recorded on mushroom, but only 3 are common. Heteropeza, pygmaea, mycophila speyeri and M.barnesi, H.pygmaca occurs most frequently.

SYMPTOMS :

With H.pygmea the loss in marketable yield due to spoilage is attributable not to only to the presence of the larvae on mushroom. But also to bacteria which are present on their skin. These cause brown discoloured stripes on mushroom stripes and gils. The delicate gill tissue can then break down to produce tiny postules of black fluid.

CONTROL :

· Observe strict hygiene throughout the farm.

· Dip wooden trays in 2% Sodium Penta Chlorophenoxide.

MUSHROOM MITES

o Mites are abundant in the compost during phase 1 composting.

o Most of the easily visible species are predatory, seeding mainly on nematode. And other species of mite which are present at this time

(1) Tarsonemid mites : (Tarsonemus myceliophagus)

Mite’s infection

SYMPTOMS :

Mites cause a reddish brown discolouration and rounding of the base of affected mushroom stipes. However, where on infestations occurs soon after spawning, large populations may develop, with a subsequent increase in damage symptoms such that the whole of the sporophore may be discoloured

CONTROL:

Ø To kill mites at the end of cropping, a normal cookout should be ample because a 20min exposure

(2) Predatory mites : (Parasites fumetorum, Digamasellus fallax, Arestoseius ceratus)

SYMPTOMS:

They cause no symptoms on the mushroom crop but, as they can easily be seen running over the surface of the casing, mushroom and trays in search if their prey, they can be a source of irritation to pickers.

CONTROL:

Ø They are beneficial mites, so no measures should be taken to control them. Identify the pests on which the predatory mites are feeding and take appropriate measures.

3) REDPEPPER MITES:

The most common mites seen during mushroom cropping are the red pepper mites.

SYMPTOMS:

RED PEPPER MITES

These mites often swarm in vast members on the surface of the casing and the mushroom, giving them a reddish-brown colour, and it is from such behaviour that they get thin common name. They feed only on weed moulds.

CONTROL:

Efficient composting and peak heating of fresh (mushroom) manure to produce a medium selective for mycelium, is the most important way of avoiding trouble with red pepper mites. Observe strict hygiene throughout farm. Make sure that composting and peak heating are efficient.

Bad harvesting practices, such as leaving cut stipes on chugs on the beds, can also encourage the development of these nematodes as they will feed on the decaying mushroom tissue.

NEMATODES

Many different species of nematodes can be found associated with decaying organic matter. These nematodes that feed on decaying mater are saprophagus, & fungal feeders are mycophagous nematode.

The swarming of nematodes of the casing surface

1) SAPROPHAGUS NEMATODES:

SYMPTOMS:

They can spawn in vast numbers on the surfaces of the casing, where they can be glistening in the light to 49⁰C is lethal to them. Dicofel is very effective when used as disinfectant for washing all surfaces such as floors, walls, tools, filling and spawning lines.

Death of pin heads

2) MYCOPHAGUS NEMATODES :

Half-empty beds – the result of severe infection of the casing layer by nematodes

SYMPTOM:

If contamination occurs early, the numbers of nematodes can reach a level sufficient to destroy the mycelium. Subsequent bacterial action infested compost to become dark and sodden, often in defined patches, with a distinctive pungent smell. These patches can increase in size from the 2^ndflush onwards

CONTROL

Where insects or nematodes are present, then dry peat should be fumigated with methyl bromide or pasteurized by steam. Observe strict hygiene throughout the farm. Ensure that the temperatures during peak heat are satisfactory. Make sure that all the spent compost is removed from the farm.

Abiotic Disorders

Ø In addition to biotic agent which adversely affect the mushrooms, there are a large number of abiotic agents which create unfavourable environment for the proper growth of mushrooms resulting in the quantitative as well as qualitative loss.

Ø These abiotic agents include low or high moisture in the substrate, pH and temperature, CO2 concentration in the room, wind velocity, fumes and relative humidity.

Ø Many of these agents make the substrate nonselective for mushroom mycelium and encourage other moulds and pests while some interfere with the normal mushroom production.

Ø Management of environment is of great significance in mushroom cultivation and any deviation from the optimum requirements may lead to various kinds of abnormalities.

The following abiotic disorders are quite frequently observed.

1. Stroma

Common Name: Stroma, Sectors, Sectoring.

Stroma are noticeable aggregations of mushroom mycelium on surface of spawned compost or the casing. Discrete aerial patches of white mycelium form a dense tissue layer on the substrate surface.

Stroma can be easily peeled from the surface of compost or casing. Stroma form on the compost in small localized areas and the smaller patches can coalesce into larger areas.

After casing, stroma may form on the casing above a patch of compost-borne stroma or on casing where stroma does not exist in the compost. Stroma on casing develops in advance of pinning but rapidly putrefies once watering begins. Mushrooms can develop on stroma, but this is somewhat unusual.

A sector is a portion of spawn that is distinctive when compared to the general appearance of spawn. A sector may be extra-white, extra dense or extra-ordinary fluffy and is always different from the normal spawn. Sectors appear on or in the compost and on the casing, and tend to disappear as the crop ages.

Removing patches of stroma does not ensure growth of mushrooms in these areas, so removal of stroma is a matter for each farmer to decide. This disorder has been commonly observed in seasonal farms in HP where proper aeration is lacking.

2. Weepers

Common names: Stinkers, Leakers

· Mushrooms described as being ‘Weepers’ typically exude considerable amount of water from mushroom cap.

· When small water droplets exude from stem or cap, the mushrooms are called leakers. These water droplets may be few in number and relatively isolated from each other or may be sufficiently numerous to cover the mushrooms.

· The distinction between a ‘leaker’ and ‘weeper’ is that the water droplets remain as droplets on the leaker mushrooms while it actually falls or flows from a weeper.

· Weepers are usually noticed since they are quite unusual. A weeping mushroom can dissolve into a white foam. Water collects on the casing surface beneath a weeper and the area develops a putrid odour becoming a ‘stinker’.

· Factors that induce a mushroom to become a weeper are not known but low-moisture compost-less than 64% coupled with high moisture casing is where weepers are frequently seen.

· The combination of these two conditions often foster weeper mushrooms prior to and during the first break. Smooth white mushrooms seems to have some sort of protection against leakers and weepers. Other major types-off-white, cream, golden white are susceptible to this malady.

3. Flock, Hard Cap And Open Veil

Common Names: Flock, Hard Cap, Open Veil, Sagging Socks.

· Flock is a physiologically induced malformation of the mushroom’s cap and gill tissue.

· The cap opens pre-maturely and the gills of the affected mushrooms are rudimentary, poorly developed and have little pigmentation.

· The flocked mushrooms generally appear in first flush and may disappear in subsequent flushes but in some cases it continues increasing in subsequent flushes.

· Environmental conditions including diesel exhaust, oil-based point fumes and certain anticorrosive chemicals in steam boilers or certain diseases like dieback, brown plaster mould and false truffle induce flock symptoms.

4. Hollow core and Brown pith

· These two disorders seem to afflict cream strains much more than other strains, although off-white strains can have hollow core.

· When the bottoms of the stems are trimmed after harvesting, a circular gap is seen in the centre of the stem.

· This hole may extend the length of the stipe or it may be shorter.

· When the hollow cut end portion is brown in colour the sale price is considerably reduced.

· This abnormality seems to be related to watering and water stress.

5. Purple stem

Common Names: Purple Stem, Black Leg, Storage Bum.

· Cut stems of the mushrooms develop a deep purple colour within few hours of harvest or after being in cold storage (36ºF) overnight.

· At times colour is closer to black than purple and it occurs in all strains smooth white, off-white, cream and brown.

· Generally mushrooms from 3rd break to the end of the crop are most susceptible.

· Polyphenol oxidase, an enzyme increases in later-break mushrooms and this enzyme influences pigment formation.

· Conditions that predispose mushrooms to this phenomenon are unknown but the frequency and the amount of water applied before harvest seems to affect its occurrence.

6. Rose Comb

· Large lumps and swelling are visible on the mushroom cap.

· The gills often grow in the top of the cap tissue and even on the top of the cap.

· These misshapen gills make the swellings look spongy.

· The mushrooms can even burst or split and then turn brown.

· The abnormality is caused by gases or vapours coming from solvents, paint or oil products and polluted casing soil.

7. Scales or crocodiles

· Scales arise through the surface tissue failing to grow while the cap develops further.

· The main reason for scales being formed is poor climate control, in particular too much drying out or too great air velocities.

· Strong vapours of formaldehyde or pest-control products in excess can also cause the outer layer of the skin of half-grow mushrooms to tear off.

· As the mushroom continues to grow, the skin bursts and so-called ‘crocodile’ skin is formed.

· The off-white and cream mushroom strains are more sensitive to scales than white mushrooms.

· This is the most common and serious malady affecting button mushroom in seasonal farms in HP.

8. Long stemmed mushrooms

· The presence of long stems in combination with a number of other symptoms can indicate virus diseases but it is often the result of too high CO2 concentration so that the stems extend more (drumsticks).

· With the improvement of aeration such conditions can be avoided.

9. Brown Discolouration

· Browning of small pin heads or half grown mushrooms is very common on seasonal mushroom farms.

· This may be caused by high temperature, sprinkling at high water pressure (maximum pressure is 0.4 atm), chlorinating with too high a chlorine rate [maximum rate is 500ml (10%) per 100 litre of water per 100m²] or incorrect use of formalin, e.g. by spraying the mushrooms with a formalin solution.