Barley Stripe

Initially, long pale or yellow stripes appear on second, third, and subsequent leaves. The stripes become a darker color as the fungus produces spores (sporulates) on the leaf surface. As the infected plant matures, the leaves split along the stripes. Infected plants are usually stunted and produce blank (sterile) spikes. Rarely, a few seeds are produced by infected spikes, and late-forming tillers may produce normal (fertile) spikes.

Barley stripe is a problem only in barley (Hordeum spp.). The fungus is seedborne and survives in the outer layers of infected seed. Coleoptiles of seedlings are infected by the fungus under cool, moist conditions.

The fungus grows systemically within the plant, where it produces toxins that kill cells and discolor leaf tissue between veins, causing the characteristic striped lesions. When conditions are wet or humid, spores are produced on the surface of leaves at about the time spikes of healthy plants in the field begin to flower. Spores are dispersed by wind to these developing spikes, where they can germinate and cause infections in developing kernels.

After infection, the fungus becomes dormant in the hull (pericarp) of the kernel until the seed germinates. Kernels are most susceptible to infection during early development. Moisture from rain or dew is necessary for spike infection. Infected seeds are symptomless though the pathogen can survive on the infected seed and cause disease when planted in future seasons. Only one cycle of infection and spore production occurs each season.

Cultural Control

Use certified seed and do not replant seed from infected fields. According to the California Crop Improvement Association, certified seed fields may not exceed five infected plants per acre.