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Bunt, or stinking
smut |
Causal organism - Claviceps purpurea
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At or near to harvest, ergots fall to the ground where they remain until the following summer, when they germinate to produce club-shaped spore bearing structures. These spores are spread by the wind to nearby open flowers of grasses and cereals. The spores germinate in the flower, infecting the 'ovaries' This infection leads to the production of a different spore type encased in a sticky secretion commonly referred to as 'honeydew' . This attracts insects which carry the spores to other flowers where further infection occurs and the process is repeated.
Short distance spread can also occur by rainsplash or direct contact with infected ears. There are a number of strains of the fungus, some of which can infect grasses and cereals, others which are restricted to certain hosts. Wheat and other cereals are less commonly affected than rye although occasionally open-flowered varieties which become widely grown can be affected. The disease is favoured by cool, wet conditions during flowering which facilitate spore production and prolong the flowering period - making infection more likely. The ergots are not viable for more than 12 months so ploughing can bury the ergots and prevent germination from depth. The ergots would then not be viable if ploughed up the following season.
