Snow Rot (Grey or Speckled Snow Mould)

Pathogen

Typhula incarnata

Hosts

Snow rot affects only winter cereals, especially winter barley, although infections have been noted in winter wheat.

Symptoms

The fungus infects the oldest leaves first but eventually the whole plant can be affected causing yellowing and wilting. Affected plants usually have abundant red-brown resting structures (sclerotia) 2-3 mm in diameter embedded in the lower leaf sheaths and on dead leaf tissue. Plants can be killed, but often good growing conditions in the spring allow crop recovery. Surviving tillers compensate for dead shoots so that yield loss is usually small. In years with prolonged snow cover, the disease can be more severe. Large areas of the crop may be killed and re-drilling with spring barley may then be necessary.

Life Cycle

Snow_Rot-life-cycle.jpg

Affected plants produce large numbers of sclerotia which can survive between crops over-winter. The sclerotia germinate and produce spores and/or mycelium which infect emerging crops. Winter-sown crops become infected during the winter months, often under snow cover. Spring sown crops are rarely affected.

Importance

Snow rot is commonly recorded but, except in isolated cases, damage is rarely severe. The disease is generally more damaging in parts of Scotland where snow cover is more common.

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