The pathogen is transmitted through contaminated seed and infected plant parts of barley. Preferably infects spring barley crops that were seeded late, because the pathogen requires warmth. Warm and arid soils are favorable for the primary infections in seedlings that start on the base of the stems. The conidia, which ripen on the infected dead plant parts from the previous season, are spread by wind and responsible for secondary and subsequent infections. The leaves and ears are infected at temperatures above 20 °C and leaf wetness of at least 16 hours.
Drechslera leaf blight [Drechslera sorokiniana]
Drechslera leaf blight - image 1
The pathogen infects the leaves, the base of the stems and ears. It can only be distinguished from other leaf spot diseases by using a magnifying glass: its stromata stand individually and carry one to two banana-shaped terminal spores. At the base of the stems, striped dark brown necroses are observed, with a fuzzy transition to the healthy tissue. With severe infection, the base of the stem rots. The lower leaves develop lesions that spread over the whole leaf. At times, dotted, spindle- to oval-shaped dark brown spots develop on the leaves (Picture 1). The spots grow together and the leaves die, whereby the blackish-brown coloration of the necroses remain. Brownish-black necroses develop on the ears. With the bare eye, leaf blight can be confused with take-all, Fusarium species or net blotch of barley (spot type). The stromata are similar to those of Alternaria and Cladosporium species.
Incorporate crop residues thoroughly. Do not select a tight crop rotation of barley and wheat. Promote rapid growth of the young plants (by seeding not too deep in favorable conditon). Do not seed winter barley too early. Do not seed spring barley too late.
No special fungicide measures, because leaf blight is well controlled with the control measures against other relevant barley pathogens starting with fungicide seed treatments.