Raspberry spur blight

Didymella applanata

Spur blight is a disease of raspberries caused by the fungus Didymella applanata. It appears from late summer and persists on infected canes until the following year.
It mainly affects raspberries and occasionally loganberries. It is particularly common during wet seasons.

Symptoms
Conspicuous purple patches on new canes in late summer, centred around the buds. They increase in size, spreading up and down the cane from the point of infection
As autumn and winter progress the patches become less distinct, fading to a pale grey or silvery colour. Fruiting bodies of the causal fungus may be visible as tiny black spots on the affected areas
Many of the buds on canes, infected the previous year, fail to grow in spring or produce weak shoots that soon die. These canes appear bare and unthrifty compared to their healthy counterparts

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