Pathogen. The grey mold fungus persists on dead or dying plant material in the soil.

Disease development. Cool, humid conditions and dense crop canopies favour infection. The fungus penetrates leaves through wounds or
diseased tissues. It can infect damaged tubers at harvest, during transit or when grading.

Plants showing typical grey mold symptoms
Dark brown lesions with concentric rings usually
develop on the tips or margins of leaflets
On leaves symptoms usually develop on the
tips of leaflets where salty water drops are
exuded by the leaflets and injure the tips
Infected leaf margins
Grey mold lesions resemble those of late blight
but can be distinguished by the dense dark
mycelium and spores produced in humid weather
Grey mold lesions can be confused with early
blight The distinctive feature is that the grey
mold fungus produces a dense grey fungal
growth on the lesions
A grey mold lesion that resembles late blight
infection
Dense fuzzy greyish brown fungal growth and
spores are produced on the stems when the
weather is wet Affected stems become hollow
The skin of infected areas is wrinkled Under
the skin tissues are soft and wet but with time
will darken and develop into a dry rot
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T.G. Lynn
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