The wheat-growing season is off to an early start due to a mild winter. Wheat fields are looking green from a distance (Figure 1), but closer examination reveals freeze damage in some fields caused by periods of subfreezing temperatures that occurred after growth had resumed (Figures 2 and 3).
While the mild fall promoted wheat establishment, it also favored survival of wheat curl mites, the leading vector of several viruses common to Nebraska wheat. While much of the state's wheat crop entered winter in very good condition, growers are urged to scout for viruses this spring and assess yield potential of individual fields when making management decisions.
A number of diseases were reported in Nebraska wheat this fall. In this article plant pathologist Stephen Wegulo outlines how to develop a comprehensive plan to tackle this yield challenge, starting with steps growers can take this winter.
Stripe rust, leaf rust, and stem rust have been identified in fall planted wheat in Nebraska, extending into areas where it had previously not developed in the fall. Plant Pathologist Stephen Wegulo looks at the outbreak, conditions contributing to rust development this fall, and the economic and management issues.
By far, the greatest risk of losses from mite-vectored viruses occurs when there is a summer "green bridge" of volunteer wheat emerging before harvest. This almost always occurs as a result of wheat seed head shatter from hail storms (Figure 1).
Stripe rust has significantly increased in all wheat-growing areas in Nebraska. It is recommended that wheat be treated with a fungicide to protect the flag leaf. If the incidence (percentage of flag leaves diseased) or severity (percentage of the flag leaf area diseased) is less than 50%, spraying a fungicide will significantly reduce yield loss due to stripe rust.