What is in this article?:
- Foliar plant diseases have been a major obstacle to stabilizing wheat yields in Northeast Texas.
- Wheat producers are challenged to employ a number of strategies to manage these foliar diseases.
- Possibilities include genetic, cultural, and chemical approaches.
Farmers have economical options to treat wheat diseases in Northeast Texas.
The first line of defense to protect against leaf and stripe rust is genetically bred plant resistance. This has been primarily true in the case of leaf rust, but in recent years, efforts have been intensified to incorporate stripe rust resistance into wheat breeding programs with good success.
Stripe rustcan be much more devastating than leaf rust. Local research has shown that yields in stripe rust susceptible varieties can be reduced by 50 percent or more in years with damaging stripe rust infection levels. Both rusts thrive on moist conditions, but stripe rust is a cool weather disease, and occurs earlier in the growing season than leaf rust. Stripe rust thrives in temperatures of 50 degrees Fahrenheit to 60 degrees, whereas leaf rust development is optimized by temperatures of 60 degrees to 70 degrees.
Plant breeding for stripe rust resistance is the best strategy to manage this disease. We do not recommend planting wheat varieties that are susceptible to stripe rust.Foliar fungicides are effective in controlling this pest, but application timing is difficult. Stripe rust spreads rapidly during cool, rainy conditions- periods when field access with ground or aerial application equipment is difficult or impossible. The only way to consistently control this disease with foliar fungicides is to spray at the first sign of stripe rust in the field. Also, since stripe rust can occur so early in the growing season in this region (prior to flag leaf emergence), a single fungicide application often will not persist long enough to protect the plants against later occurring leaf rust and glume blotch infections.
Leaf rustis the most widespread foliar disease in the United States, and the primary emphasis of plant breeding programs is resistance to this disease. Many high yielding varieties with good resistance are available to wheat producers in this region. Foliar fungicides can be used to supplement genetic resistance when leaf rust races mutate, which can change resistant varieties into susceptible ones.
Glume blotchis not a commonly occurring disease in Northeast Texas. It has been observed at damaging levels only four or five times in the past thirty years. However, when it does occur, it can cause yield losses of 10 percent to 20 percent. Glume blotch spores are spread by splashing raindrops, and damaging infections spread during warm and rainy conditions during the grain filling period. The grain fill is impaired, causing shriveled grain and reduced bushel weights. Some varieties appear to be more susceptible to this disease than others, but none of our locally adapted varieties are resistant to this disease. The only effective strategy to control glume blotch in this region is a foliar fungicide applied after heading.
Powdery mildewis a cool weather disease that infects the leaves in the lower canopy during the late fall and early winter months in this region. The best way to manage it is to plant resistant varieties. Foliar fungicides will provide suppression of this disease, but are not as cost effective as planting resistant varieties.