Barley leaf rust (Barley brown rust)
Small brown, orange pustules may occur on all aerial parts of the plants. They are most frequently seen on the leaves. Individual pustules are larger about 1 x 1 - 2 mm in diameter. Frequently a chlorotic halo surrounds individual pustules. In the early stages of the disease, pustules may by quite difficult to detect, but as the disease progresses the leaves can develop an overall brown appearance. Pustules are scattered at random on leaves, not in stripes. Towards the end of the season, dark telia may develop.
Occurrence and importance
Brown rust of barley is probably more common than yellow rust. Brown rust is world-wide distribution. The disease rarely exceeds 3% leaf area affected, but severe disease epidemics can occur in individual crops where yield losses of 30% have been reported. As brown rust is generally a "higher temperature" disease than yellow rust, it usually occurs later in the season and is frequently found on the flag leaf of cereals. This increases its significance with regard to yield losses.