Plant species specific disease that overwinters as a mycelium on volunteer cereals or winter cereals. The spores are spread with the wind. Mild fall and winter weather, a warm spring and high nitrogen fertilization are favorable for the pathogen. The epidemic spread often takes place only after ear emergence. Brown rust may also goes through a full development cycle with core phases with meadow-rue as an alternate host, although this is insignificant under Central European growing conditions. Triticale, is less prone to significant yield losses even with high infection rates.
Brown rust [Puccinia recondita]
From the growth stage stem elongation, rust brown, oval, irregularly distributed pustules (urediospores) develop on the upper leaf surface (Pictures 1 & 2). They are more rarely found on the underside of leaves, the leaf sheaths and the ears. The pustules are often surrounded by a light-colored corona ("green islands"). Just before florescence, blackish-brown pustules are observed on the underside of the leaves (teleutospores). Brown rust can sometimes be confused with yellow rust because similar colors can occur. However, with yellow rust, a clear distinguishing characteristic is the striated arrangement of the pustules.
Interruption of the "green bridge" through timely elimination of volunteer cereals. Cultivation of more tolerant varieties as well as early varieties. Winter wheat should not be seeded too early. Balanced N fertilization (avoid excess nitrogen).
When the initial infection has been detected, application of a fungicide with a residual effect.