Puccinia striiformis Westend. Generally throughout wheat production areas at high elevations and in the northern and southern areas of temperate regions. Losses of 40 percent can be common with some fields totally destroyed. It is a major disease of fall seeded wheat in regions with cool nights or of spring wheat planted adjacent to infected fall seeded wheat.
Severe losses result when spikes are infected.
The small yellowish uredinia appear in linear rows on the leaf. A single infection can result in a stripe the length of the leaf. Uredinia also can occur in the spike. Stunting of plants is common with severe early infections. Infection occurs from 0 to 25 C, with free water on the leaf and may occur beneath the snow.