Disinfection of the Casing Layer

The only harmful organisms found in peat are the nematodes, but tests determined that when materials containing lime are added, increasing the pH, the amount of nematodes was decreased down to a reasonable level. It can be assumed that most nematodes don’t survive, when the pH level changes greatly in their surrounding environment.

The infection of the casing layer can happen:

• When hygiene isn’t maintained while transporting the prepared casing layer;
• At improper storage of the casing mixture and its components;
• At improper preparation of the casing layer, the use of dirty machinery and equipment, and the contact of its components with soil and dirty floor;
• When hygiene isn’t maintained on the farm, the presence of flies etc.

Before the mixture and its components are delivered to the farm, the floor is thoroughly cleaned and disinfected with formaldehydes and other potent agents.

If there are any doubts about the sterility of the raw materials for the casing layer, or if they are stored in the farm for a long period of time, they should be disinfected before use.

The casing material can be disinfected by two methods: a thermal method (steaming) and a chemical method.

At using the thermal method, it is recommended to treat the casing mixture with steam of low pressure at the temperature of 60-65°C for 6 hours. It is considered that with this temperature level and duration of the process helpful micro flora and the pathogenic organisms’ competitors are preserved.

At using the chemical method, the casing mixture is treated with 2% formalin solution. 1 liter of formalin (40% of formalin solution) is required for 1m³ of peat. The disinfection process must be carried out at a temperature not less than 16°C, hence at lower temperature the formalin doesn’t evaporate and therefore, it’s not effective.

Before applying the casing layer to the compost, it should be kept under a film. While storing the casing mixture or prepared peat, it’s very important not to allow the contact of the material with soil, or the ingress of compost remains – the waste products of mushroom cultivation. The optimal choice is to store the mixture and peat in separate clean rooms on a concrete floor.

At using «clean» materials, that is, those which are free from pests and diseases, the preventative disinfection can be carried out after the application of the casing mixture to the beds. These treatments won’t have an effect on the condition of compost, but will disinfect the casing layer. Right after it’s applied, the casing layer should be watered with 1 liter/m² of formalin solution (2 liters 40% of formalin is dissolved in 100 liters of water and used to water 100 m² of the casing layer surface) it’s very important for the solution to reach every part of the bed. The next day, insecticide is applied to the casing layer – dimilin (4g/m²).