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Dried mycelium and/or small pins often occur when the environmental conditions are disturbed. The symptoms are caused by too much and too dry air being blown over the beds, caused when the fresh air inlet position being set too high and the RH of the rooms are too low. Mycelium is highly sensitive to dehydration during the ventillation period and pinheading stages.

During this phase the casing soil should be still shiny with moisture, rather if the mycelium suffers from a low RH combined with a higher fan position. Then after five to eight days during the pin development stage, the grower will notice that the casing soil surface dehydrates.

This disturbs evaporation and causes pin growth to stagnate. The whole process is slowed down and results in too few pieces and a first flush with too little or no flush. This dehydrated casing soil is seen clearest at the edges of the shelves or bags where the air ducts are placed.

Try to prevent this problem by working with a correct RH, a lower minimum fresh air inlet position, higher CO2-level, less aggressive circulation and possibly wetting the floors more frequently. Ensure the surface of the casing soil always feels cool and damp. If dehydration is noticed it’s a good idea to apply ½to ¾ liters of water per square meter.

Drying after spraying is usually not necessary. Repeat this step twice if required.

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