Bacterial blotch

Is this a Minor Pest?
Minor Pest Title

Bacterial blotch (Pseudomonas tolaasi)

Minor Pest Description

The main source of bacterial blotch in the mushroom farm is the casing soil. The disease is favoured by dampness [high humidity (over RH 85%), high temperatures (over 20°C ) and poor ventilation in the growing houses]. It can be spread by the workers' hands, irrigation water and on the inventory. Mushroom flies and mites also spread the disease. The first disease symptoms appear in areas of caps that have been moist for a longest time and areas where mushroom caps touch.

Symptoms include spots that darken becoming chocolate-brown in colour and slimy. It can also cause distortion and splitting of the stipes. When the infection is severe, spots spread throughout the whole mushroom surface. Seriously diseased mushrooms can become deformed and the caps can decay giving a foul (unpleasant) odour. Young pins affected by the disease become brown and do not further develop.

Minor Pest What to do.
  • Maintain strict hygiene and sanitation in mushroom facilities
  • Use properly prepared substrate and casing soil that have been adequately pasteusterized
  • Avoid excessive humidity, high temperatures and poor ventilation in growing rooms
  • Avoid fluctuation of temperatures in the growing rooms which may cause water condensation on mushroom caps
  • Remove diseased mushrooms which can be a source of the disease
  • Control mushroom flies and mites which can spread the bacteria
  • Water mushrooms with chlorinated water (125 ml 10% chlorine solution for 100 l of water per 100 m2. Use calcium hypochlorite products since sodium hypochlorite may burn caps) before first break when the pin size is 4-5 mm
  • Remove spent substrate from the farm. It can be used as manure for other crops
Minor Pest Firstcontent
Scientific Name

Pseudomonas tolaasi

Pest Type
Host Plants
Host Plants