Pyrenophora graminea is a disease of Barley that causes significant yield losses.
Life cycle and appearance of Leaf stripe
Pyrenophora graminea is monocyclic, which means there is only one disease cycle during the cropping season. The fungus is seed-borne and this systemic infection is the only source of primary infection. The fungus spreads from the seed into the seedling. Conidia are produced on the infected leaves when humidity is high and wind-dispersed to neighbouring ears where they can infect seeds at any stage up until soft dough stage. Infection occurs between 10 and 33 °C. Infected seeds can look healthy and do not necessarily show symptoms of infection. Soil temperature during seedling emergence is critical for infection.
Soil temperatures below 12 °C are most conducive for this disease and infection does not occur at soil temperatures above 15 °C.
Symptoms first occur on the first, second and third leaf and subsequently on other leaves. Yellow stripes are formed at the base of the leaf and the leaf sheath. They gradually extend and become brown and chlorotic and may merge. Eventually this leads to the death of the leaf. The leaf splits at the end which makes it look shredded. This is typical for this disease.
Infected plants may be stunted and heads may be distorted and failing to emerge from the sheath. Ear length and the number of kernels may be reduced and kernels may be brown. The symptoms do not always occur together.