The fungus that causes septoria leaf blotch overwinters on crop residue, before releasing two types of spores. The first are dispersed a short distance by rain splash, and the second are dispersed across long distances by the wind. The disease thrives in warm, wet weather.
Initial symptoms of infection include small spots on the lower leaves of plant seedlings, which are yellow to brown in appearance. These eventually expand into large, lens-shaped lesions, grey to brown in the middle and yellow along the edges. The lesions may also contain small, dark, spore-producing spots. The disease causes shrivelled seed and reduced seed set, decreasing yields.
- Allow a one or two year break between cereal crops
- Use varieties with some resistance
- Burying crop residue may reduce incidence of the disease
- Monitor crops closely around flag leaf emergence, and spray only if small spots have appeared on the upper leaves. In this case, foliar fungicides can reduce losses.
- Seed treatments will reduce disease transmission from seed, but not from crop residue, which is the main source of the spores
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