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Spur blight is a disease of raspberries caused by the fungus Xenodidymella 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.

You may see the following symptoms:

• Conspicuous purple patches on new canes in late summer, centred around the buds
  A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers. . They increase in size, spreading up and down the cane
  A cane is a slender, straight, length of woody plant material, usually bamboo. Canes are primarily used as plant supports. The fruiting stems of blackberries, raspberries and hybrid berries (such as loganberries and tayberries) are also known as canes, so these crops are often referred to as cane fruit. 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 dots 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

Non-chemical control

• Avoid overcrowding by thinning
  Pulling out some of the seedlings, usually along a row, so the remaining seedlings are spaced further apart. It reduces overcrowded, which can hinder their growth. out any young canes that are not required. This should be done as early in the spring as possible
• Avoid the over-application of nitrogen
• If spur blight develops, cut out and dispose of badly affected canes
• Choose resistant cultivars. The cultivars ‘Glen Lyon’, ‘Glen Moy’ , ‘Glen Rosa’, ‘Julia’, ‘Leo’ and ‘Malling Admiral’ have some resistance to spur blight

Chemical control

No fungicides are available to home gardeners for the control of raspberry spur blight.

Xenodidymella applanata produces two spore types. The first type starts the infection on the new canes in the spring, while the second causes further spread during the summer. Infection usually occurs via the leaf stalks or buds

A bud is a small, undeveloped shoot that contains the potential for new growth. Buds are typically found on stems, where they can be apical (found at the tip) or axillary (found between leaf axils) and may develop into leaves, shoots or flowers. , and is favoured by wet weather.

Overcrowded canes, and those that have received too much nitrogen, are more prone to attack.