Mycogone

Mycogone perniciosa.

This mushroom disease has a few often used names: «Mycogone», «Wet bubble», «white mold», «vesicular disease».

The word «Mycogone» is of Greek origin: Myco – «mushroom of fungus», and the suffix «gone» means a reproductive body. This mold got its name because it tends to parasitize on a mushroom fruit body.

Mycogone mycelium on a mushroom fruit body
Mushrooms that have been affected by the disease on an early stage turn into a shapeless mass, covered with the parasite’s white and fluffy mycelium. As the deformed mushroom develops, it becomes brown and starts to decay. Due to the watery decaying and the shape of affected mushrooms, this disease got the name «Wet bubble». Moreover, little droplets of liquid amber in color appear on the surface of mushroom tissue, especially at a very high level of humidity. On this stage, the mushroom begins to rot and that is accompanied by a objectionable odor. Under dryer conditions, the deformed mushrooms can have hideous offshoots, but their tissue will remain dry, like with the Verticillium disease (dry bubble or fungus spot).

Also, besides the deformation symptom, small, white and fluffy spots of Mycogone mycelium that parasitize on the mushrooms developing under the casing layer, appear on the surface of the casing layer. If ripe mushrooms become diseased, only the base of their stipe is affected. First, its color changes to brown, and later, white and fluffy mold mycelium appears. If the diseased stipes are left on the beds after the mushrooms are cut, they can become the source of the disease spreading. Sometimes, a brown stripe on the stipe can indicate damage, along with symptoms that look like sectors of damaged and wilted plates, covered with the typical white mycelium of the parasite.

Under dry conditions, the mushrooms affected with Mycogone have hideous offshoots, but their tissue remains dry, like with the Verticillium disease

At a high level of humidity, droplets of liquid amber in color appear on the deformed mushroom tissue – this is a typical sign of Mycogone
Mycogone is a disease that often occurs on mushroom farms. It can be of very severe (when there are practically no healthy mushrooms left on the beds), and not that much (unitary diseased mushrooms). Everything depends on:

• the time when the infection occurred;
• the degree of infection;
• and the mushroom grower’s attitude toward this problem.

The primary source of Mycogone infection is mostly the casing layer. The mold’s habitat is soil, and when it gets into the casing layer and/or the farm, a disease outbreak happens.

The more the casing layer is infected with the Mycogone perniciosa fungus, the greater the yield loss. Small areas of infection indicate a low level of the casing layer infection or a later entrance of pests into the mushroom culture. This can happen when the sanitary regulations are not followed (the use of dirty instruments, crates and equipment by mushroom pickers), or a secondary infection (that is when the fungus enters other growing rooms) because there are no air filters, and the presence of flies on the farm or wastes, that are infected with Mycogone.

The disease can spread by spores and pieces of mycelium, adhering to any objects that touch the fungus.

Mycogone perniciosa forms two kinds of spores:

• conidiospores (unicellular, thin-walled spores, with a relatively short life, very light, therefore, they can be carried by wind);
• chlamydospores (consist of two cells, thick-walled, brown spores, that life for several years).

Both kinds of spores are spread easily when the beds are irrigated. This is why the irrigation should be carried out only after all mushrooms affected with Mycogone are removed. It’s best when this operation is carried out by a team of specially trained «orderly» ,that inspects the beds everyday. All diseased mushrooms can be removed before harvest and the affected areas can be strewed with salt. Due to this, there are fewer chances for the fungus to be spread by pickers through spores and pieces of mycelium on hands and tools.

Diseased mushrooms must be harvested very carefully. In literature, the following recommendations are given:

• harvesting the diseased mushrooms with a spoon, lowering the mushrooms into a copper sulfate solution and disinfecting the spoon after removing each mushroom;
• strew the affected mushrooms with salt or cover them with plastic pot (the pots must laid as deep as possible, so it reaches the compost, and so that water doesn’t reach the affected mushroom);
• unitary areas of the fungus can be strewed with salt or watered with a formalin solution and then strewed with ground lime. These areas can be completely removed the next day, grasping the casing layer of a larger diameter.

But the main mean of protection - is the exclusion of the initial infection of the farm, that is the observance of the sanitation and hygiene regulations, and storing the materials used for the preparation of casing soil in a place where infection can’t get in. Disinfect the casing layer after its preparation and store it in a clean room.

If the infection occurred anyway, the possibility of its spreading must be brought down to a minimum. Even one source of Mycogone that has been left without attention, can be a source of infection of a great amount of mushrooms and can cause a considerable yield loss. It is very hard to fight the disease. The spores of this mold can adhere to any surfaces in the rooms, on building walls, it is carried by personnel, with mushroom wastes etc, infecting the whole farm that way.