Pathogen 

• Pyrenophora graminea (Drechslera graminea)

Hosts

The disease is specific to barley.

Symptoms

The disease is seed-borne and causes long brown stripes on the leaves. The stripes are often pale green at first, becoming yellow and then finally dark brown. Usually all of the leaves of affected plants show these symptoms and some leaves split along the stripes giving the leaf
a shredded appearance. Symptoms are usually most prominent at ear emergence. The disease is generally most severe on crops which have been grown from untreated seed.

Leaf stripe can affect the plant in three ways; first it can kill seedlings as they emerge. This is unusual but can occur if soil conditions are very poor. Secondly, it can reduce the efficiency of the plant by reducing green leaf area and thirdly, it can result in complete blindness of the ear resulting in no harvestable grain from affected tillers.

Life cycle

The fungus is present on the seed surface and as mycelium in the seed coat. As the coleoptile emerges, the fungus invades the tissue and penetrates through to the emerging first leaf. The fungus grows through successive leaf sheaths, producing the characteristic symptoms on each leaf until it infects the ear which often remains in the leaf sheath. Although the fungus produces spores on the stripes these are not thought to be very important in the UK as a means of spreading the disease.

Importance

This is potentially the most serious seed-borne disease of barley. If seed from affected crops is re-sown without an effective fungicidal seed treatment being applied, the disease can multiply very significantly and produce large yield losses. If seed is saved and re-sown repeatedly, complete crop loss is possible within a few generations of seed multiplication.