This PPT deals with the Mushroom bacterial disease - Bacterial blotch

1. Mushroom diseases
Dr.M.Manigandan

2. Introduction
• Mushroom diseases can be caused by both fungi and bacteria.
• A.G. Tolaas 1915, organism named after Sydney Paine in 1919.
• The most commonly cultivated mushroom is the Agaricus species.
• Once the disease is introduced in the farm, secondary infection can be
carried out by different agents such as air, water, machines, unhygienic
equipments and handlers.
• The important fungal, bacterial and viral diseases and their causative
organisms , symptoms and control measures are followed

3. Types of bacterial diseases in
mushroom
•Bacterial disease
• Bacterial blotch – Pseudomonas tolassi
• Mummy disease - Pseudomonas spp.
• Drippy gill - Pseudomonas agarici

4. Bacterial blotch
• Common bacterial diseases in
mushroom
• Causes bacterial spot
• No healthy crops and in poor
ventilation system, compost, casing,
water splash, equipment, pickers,
insects, and mites.
• Low temperature
• Leads to total crop loss

5. Significance
• Crop loss 5 – 15%/ mushroom farm
• Loss in crop value range from $500K to &2 million
• Mushroom looks process instead of fresh
• Post harvest symptoms occurs during shipping/storage.

6. Characteristics of pathogen
• Pseudomonas tolassi (Phytomonas tolassi, Bacterium
tolaasi)
• Gram-negative
• Flagellated/motile
• Ubiquitous in soil
• Non-host specific
• Toxin production
• Pseudomonas fluorescens (biotype G) – formation of
lesions

7. Symptoms and conditions
• Present on the cap
• Mushroom cap wetness for long time leads to pathogens
multiplication.
• Lesions on mushroom tissue that are pale yellow initially, but
which later become a golden yellow or rich chocolate brown
• This discoloration is superficial, no more than 2 to 3 mm
deep, and the underlying mushroom tissue may appear to be
water-soaked and grey or yellow-grey.
• In extreme cases, usually with late flushes, distortion of
emerging caps is observed.

8. • Bacteria growing on cap surfaces may cause affected
tissue to have a slippery feel.
• Stalks can be attacked.
• Blotch usually appears on the early stage, also re-appears
on any stage of growth.
• Decreases the quality of mushrooms
• No harm to human health.

9. Types of mushrooms infected
• ❖ Agaricus
• ❖ Agaricus bisporus (button mushroom)
• ❖ Agaricus campestris
• ❖ Flammulina velutipes
• ❖ Lentinula edodes
• ❖ Pleurotus eryngii
• ❖ Pleurotus ostreatus (oyster mushroom)

10. Prevention and Controlling
measures
• Chlorinating the irrigation system – 150ppm
• Potable drinking water utilsed
• Ambient temperature
• Humidity reduced to less than 85%
• Effective pasteurization.