Stemphylium is an important disease in various crops. It can cause leaf spots on infected plants from a very early stage. This is particularly damaging to baby leaf crops. The leaf spots are circular or oval in shape and pale grey-green in colour. The lesions are initially less than 5 mm in diameter, but become larger and turn pale brown. Unlike most other diseases, there are no clear signs of fungal sporulation and these lesions can be attributed to a chemical scorch mark. The foliage can be damaged by the lesions coalescing, which is exacerbated by pollen on the leaves of seed crops. There has been some progress in the development of resistant cultivars. Seed treatment can contribute significantly to effective control of this disease.
