Growing Mushroom: Mushroom Diseases and How to Control

Background

Mushrooms are classified as an edible fungus. With millions of harmful fungi all around, it can be challenging to cultivate mushrooms successfully. Major diseases have been recorded to pose and cause threats to the cultivation, which leads to the closure of production units. All this together, understanding the diseases and factors that contribute to their spread can make a huge difference. Below we take a look at the major diseases affecting mushroom production.

1. Green Moulds

There are different species of green molds that a cultivator may encounter. The Trichoderma, Aspergillus, Penicillium, and Cladosporium are some of the major species encountered in mushroom production. The mode of attack is characterized by a dense white mycelium, that grows on the top of the substrate. Later on, the color changes from white to green indicating the green mold attack.

Mode of spread

Primarily, poor compost preparation i.e., during pasteurization or sterilization facilitates entry and spread of green mold. The attack during production is greatly spread by flies, workers, equipment, and wind. Also, it should be noted that different conditions favor the growth of green mold. For example, nitrogen-rich compost may be more susceptible to attack by green molds or optimum climatical conditions that support their growth.

Disease management

Mainly, procedural preventive methods should be adopted. Firstly, compost pasteurization or sterilization should be done with the required standards. Secondly, insect-proof nets should be mounted to any opening in the production house. Thirdly, disinfectants should be placed at the entry of the production house. Proper sterilization of operation tools should be encouraged, and general worker hygiene should be adhered to.

2. Dactylium Disease (Cobweb Mold)

The disease presentation is like soft cotton on top of the colonized substrate. The heavy multiplying mycelium is referred to by many as cobweb mold. The attack starts with the formation of small spots, which later spread colonizing anything on their way. The colonized mushrooms, weaken, develops soft watery spots, and rot due to anaerobic respiration. The fungi mycelium has got different color variations from white, grey, to pink as it matures.

Mode of spread

The causal organism is hyponyce rosellus, which lives in the soil. Casing with untreated soil is the start of the infection. Spot infected casing layer shows symptoms of the disease during the early stages, that is, during the pining stage, unlike heavily infected casing layer that shows the symptoms during late stages. During spore production, a windy environment encourages the spread of the disease. Splashing of water to healthy casing materials also facilitates the spread.

Disease management

Soils infected with Hypomyces rosellus, a soil-borne fungus should be treated first before use. Through proper heating or chemical treatment, a grower can eradicate the fungus. High levels of humidity and air temperatures in the growing room have been noted to favor the first growth of the fungi mycelium. Reducing these factors should be considered in case of strong attacks. Post-harvest hygiene procedures, that is, removal of all debris from the beds, sterilization of equipment used, and sanitation of the farm in general should be adopted.

3. Verticillium spot (dry bubble)

The disease forms a leathery surface on the top of the mushroom caps. The leathery surface has got brownish appearance with black spots on them. Despite its appearance, the mushroom neither decays, produces drops of liquid nor any unpleasant odor, hence the name dry bubble. This quit the opposite with “wet bubble” disease. The fungus first appears less harmful and of no economic importance but later colonizes the whole crop if left untreated. Deformation of mushroom bodies is the main characteristic associated with the fungus.

Mode of spread

The source of the verticillium spot is an infected casing layer. Similarly, a production house poorly mounted with insect nets, contributes to the attack by verticillium. As the mushroom matures the verticillium spots change to greyish-brown in color. This is facilitated by the high levels of humidity, turning the spots to grey mold. Unhygienic personnel on the farm also facilitate the spread of the fungus.

Disease management

The causal agent Verticillium fungicola var. fungicola, can be denatured by exposing it to extreme temperatures or by use of chemicals. The production house should be well secured from flies and rodents’ infections that may lead to contamination. Early identification of the disease saves the production. A grower should make sure proper disposal is done to the discarded bags once identified.

4. Mycogone disease

Also, known as the white mold or the wet bubble disease. The diseases parasitize on the fruiting bodies of other mushrooms eventually devouring them. Mushroom bodies attacked by white mold lose their shape, becomes watery, and start to decay, hence the name wet bubble. The oozing liquid is of unpleasant odor. On top of that, small, white, and fluffy mycogone mycelium starts to develop under the casing layer. For mature mushrooms, an attack is mainly noted at the base of the stipe. The color changes from brown to white then a fuzzy mold mycelium is seen.

Mode of spread

The fungus Mycogone perniciosa habitat is the soil. Casing with contaminated soil is the primary cause of mycogone disease. Relatively higher humidity, facilitate the spread of the diseases. This occurs when droplets of liquid, amber in a color, form on the surface of the deformed mushroom tissue. The fungus is common due to its mechanism to produce two kinds of spores, one with a short life, and the other lasting several years. The spores are light, hence spread easily throughout the grow house.

Disease management

During harvesting, the use of a spoon is done to scoop the fluffy mycelium and wash the spoon with copper sulfate solution. Watering should be done only after the affected mushrooms have been removed to prevent infecting health beds. When casing, healthy soil and proper standards of hygiene should be observed.