Oyster mushrooms turn yellow: why, what to do

Oyster mushrooms are quite resistant to diseases and pests. It is for their unpretentiousness that mushroom growers appreciate them. However, even with them there are problems with artificial cultivation. It happens that the oyster mushroom turns yellow, and also dries and cracks. Most often, the reasons are in errors of care, the appearance of a disease or an attack by pests.

Why oyster mushrooms turn yellow

This can happen to oyster mushrooms at any time, regardless of the growing stage. They can turn yellow for the following reasons:

  • high humidity in the room;
  • too dry air;
  • inadequate ventilation;
  • drafts;
  • pests;
  • illness;
  • sharp changes in air humidity.

The color of the caps may become uneven. The appearance of yellow spots is due to the following factors:

  • poor substrate;
  • fungal or bacterial disease;
  • impossibility of evaporation of water droplets falling on oyster mushrooms during watering or with high humidity.

Yellowing of fruit bodies

What to do if oyster mushrooms turn yellow

First of all, you need to find out the reasons for this phenomenon. It is impossible to control the microclimate in the mycelium by eye, so you need to purchase a special device that will help maintain optimal humidity.

If oyster mushrooms are covered with a yellowish coating, then most likely the humidity is too high.

If the caps not only turn yellow, but dry out and crack, and the legs darken, then this indicates too dry air.

If the humidity is normal, but there are yellowish spots on the oyster mushrooms, this means that there is no ventilation or does not work well.

Drafts can cause cracks, so it is important that the ventilation system does not create them. Air flows should not go at the level of growth of oyster mushrooms, their path should be directed higher and lower.

Important! It is necessary to maintain constant air humidity in the oyster mushroom growing room (from 83 to 93%). For fruit bodies, its sharp jumps are destructive: they turn yellow, dry and crack, or vice versa, freeze.

To exclude infections, you need to rip off the fruiting body and do an analysis to identify the pathogen. Microorganisms can be in the substrate, so it needs to be checked. If a pest is found, it is necessary to treat it together with oyster mushrooms with special preparations.

Other diseases of oyster mushrooms and their elimination

There are other diseases of oyster mushrooms, due to which they can turn yellow. The mushroom picker should be well versed in them.


Oyster mushrooms can turn yellow with bacteriosis. They don't get this disease very often. This usually happens during the warm season, when the air temperature is quite high and the humidity is high. The symptom of this disease is the appearance of spots on the surface of the fruiting body, the color of which varies from beige to rusty brown. Gradually, their surface becomes covered with mucus.

The cause of the disease is a bacterial infection caused by Pseudomonas tolaasii. The pathogen can enter the fruiting body from the soil. You need to pay attention to the following signs:

  • yellow dots and spots are slippery when touched with hands;
  • the spots have no clear edges;
  • when pressed, the pulp is cotton and falls through;
  • the fruiting bodies give off a very unpleasant odor.

Oyster mushroom bacteriosis makes them unusable

It is impossible to determine exactly the presence of the disease and its causative agent by eye; it is necessary to conduct a laboratory analysis that will help identify it. If no infectious agent is found, then it is not bacteriosis.

If the red spots have well-defined borders, then this is not a bacterial infection. Dots and small specks (less than 1 mm) of a rusty, brownish-red color are damage caused by flying insects or larvae in the substrate.

If the spots are single and larger in size (from 2 to 3 mm), then these may be traces of drops of condensation or water that got on the fruit bodies during watering.

If the problem is in the soil, it is useless to treat oyster mushrooms. A fungus infected with a bacterial infection emits an unpleasant odor and becomes overgrown with spots. Diseased clusters must be plucked and destroyed.

With frequent lesions of oyster mushrooms with bacteriosis, it is recommended to add calcium chloride to the substrate.


If the fruiting bodies turn yellow, it can be caused by mushroom gnats, midges and other pests. The mushroom scientist usually does not notice the parasites themselves: he does not pay attention to single flying midges, and the larvae are inside the mushrooms.

Mushroom mosquitoes are especially dangerous, which significantly reduce the quality of mushrooms and the yield. Sciarids are most often found on oyster mushrooms. Their females lay their eggs in the substrate under the film next to the perforations. The larvae that emerge from them feed on mycelium. The development cycle of mosquitoes is shortened at high temperatures and lengthened at lower temperatures. Mature individuals do not fly far from the blocks with the substrate and, after mating, lay their eggs again under the film.

Mushroom midge larvae

In case of mass infection, they are able to completely destroy the rudiments of fungi. In addition, sciarids can be carriers of diseases and other pests.

If the mushroom shrivels and begins to turn yellow, you need to remove it from the substrate and examine the root under a magnifying glass. You can find the moves made by pests and the larvae of midges or mushroom mosquitoes themselves. Outwardly, they look like orange, white, or pink worms.

Rusty spots scattered over the surface of the fruiting body may also indicate the presence of larvae.

It is necessary to fight mosquitoes and midges by treating the room where mushrooms are grown, such as Fastak, Arrivo, Decis Lux, belonging to the pyrethroid group, as well as preparations based on organophosphorus compounds, for example, Nurel. To destroy the larvae, insecticides are introduced into the substrate while feeding the mycelium.

Attention! Pests can develop resistance to the drug with constant use. It is recommended to alternate funds from different groups.

Prevention of diseases of oyster mushrooms

First of all, it is required to create optimal climatic conditions.

The growing room must be well insulated so that condensation does not form on the walls and other microorganisms cannot grow on the ceiling.

It is necessary to carry out sanitary and hygienic measures, that is, to maintain cleanliness and control the development of diseases and the appearance of pests. Indoor floors and walls, equipment and tools should be cleaned and disinfected.

For prevention, treatment is carried out with such drugs as a solution of bleach, "Whiteness", chloramine, hydrogen peroxide and others. It is recommended to strictly adhere to the instructions when using them and periodically change the funds in order to avoid the addiction of harmful microorganisms to them. It is desirable that the floor and walls are smooth, so it is easier to wash them before proceeding with disinfection.

One of the most effective broad-spectrum drugs, directed against bacteria, viruses, fungi

When working with chemicals, it is necessary to use personal protective equipment: an apron or a dressing gown, boots, gloves, glasses, a hat, a respirator.

Often, the covering soil becomes a source of infection for fungi, which must be treated with steam and formalin. The materials for its preparation must be stored correctly - in non-contaminated places.

For the prevention of fungal midges, insecticides are used, which are sprayed on the growing rooms.

So that the larvae do not hatch from the eggs of harmful insects laid in the substrate, drugs are introduced into it that block the synthesis of chitin (Dimilin, Fetoverm).


If the oyster mushroom turns yellow, it is necessary to find out the causes of the phenomenon. To prevent this from happening, it is important to initially create the right conditions for the mushrooms and take preventive measures to process the premises and growing environment.

Watch the video: The beginners guide 9 steps to growing oyster mushrooms on coffee grounds and shredded paper (September 2021).