Spot blotch (wheat)

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Spot blotch is a leaf disease of wheat caused by Cochliobolus sativus.^[1][2] Cochliobolus sativus also infects other plant parts and in conjunction with other pathogens causes common root rot and black point.

[edit] Symptoms

Early lesions are characterized by small, dark brown lesions 1 to 2 mm long without chlorotic margin. In susceptible genotypes, these lesions extend very quickly in oval to elongated blotches, light brown to dark brown in colour. They may reach several centimetres before coalescing and inducing the death of the leaf. Fruiting structures develop readily under humid conditions and are generally easily observed on old lesions. If spikelets are affected, it can result in shrivelled grain and black point, a dark staining of the embryo end of the seed.^[3] The small dark brown spots on the leaves contrast with the larger, light brown spots or blotches produced by tan spot and septoria avenae blotch.^[2]

[edit] Crop losses

In recent years, Helminthosporium leaf blights (HLB), caused by both Cochliobolus sativus and Pyrenophora tritici-repentis, have emerged as serious concerns for wheat cultivation in the developing world.^[3]

[edit] References

1. ^ Wiese, M.V. (1987). Compendium of wheat diseases. American Phytopathological Society, 124 pp. 
2. ^ ^{a b} Martens, J.W.; W.L. Seaman, T.G. Atkinson (1984). Diseases of field crops in Canada. Canadian Phytopathological Society, 160 pp.. 
3. ^ ^{a b} Duveiller, E.; H.J. Dubin. Helminthosporium leaf blights: spot blotch and tan spot. FAO Corporate document respository.