March 23, 2005
Wheat Growers Need to Keep an Eye Out for Leaf Rust
LINCOLN, Neb. — Nebraska wheat growers need to pay close attention to leaf rust development in their fields before wheat flowers this spring, a University of Nebraska plant pathologist said.
In general, Nebraska's wheat crop looks normal for mid-March, said John Watkins, plant pathologist in the university's Institute of Agriculture and Natural Resources. However, rust overwintered in some wheat in parts of Nebraska so producers need to keep an eye on their fields, he said.
Typically, leaf rust does not overwinter this far north, Watkins said.
"However, some fields surveyed had orange leaf rust pustules on the lower leaves," he said. "What is different this year is that last fall a significant leaf rust outbreak occurred in the Panhandle and in parts of west central and south central Nebraska."
In addition, weather conditions last September and October were ideal for rust development. Rust thrives in wet, warm weather.
"Some of this rust apparently survived the winter on the lower, more protected leaves," Watkins said.
Conditions are similar in Kansas and Oklahoma, where leaf rust also overwintered. Unseasonably warm weather in February and March has accelerated the maturation rate of winter wheat and also is resulting in much higher levels of leaf rust from Texas to central Kansas, he said.
Research elsewhere indicates that rust at flowering can result in a 15 percent yield loss.
"With the current rust situation in three states to our south and with the presence of leaf rust in some Nebraska counties along the Kansas border, Nebraska producers should pay close attention," Watkins said.
Certain fungicides may be used for an early, low-rate application when spring herbicide is applied. If this is done, it should be followed by a second treatment during the boot to flowering stages of wheat.
"The other option is to wait and see what happens with the rust and then, if necessary, apply a fungicide," he said.
Last fall's weather also was favorable for wheat growth. Some wheat put on extensive growth – as much as 8 to 10 inches. This excessive growth has led to significant cold temperature dieback in west central Nebraska, north of Imperial.
For more information about leaf rust, consult Nebraska Cooperative Extension NebGuide G95-1245-A, Rust Diseases of Wheat: Leaf, Stem and Stripe, available on the Web or Nebraska Cooperative Extension NebFact NF02-559, Wheat Disease Fact Sheet No. 1 Management Program for Rust Diseases of Wheat, available on the Web. Both also are available from local extension offices.
For more information about applying fungicides, visit Crop Watch, extension's crop production newsletter, on the Web.
3/23/05-SAK
John E. Watkins - Ph.D.
Plant Pathology
Professor
(402) 472-2559
Sandi Alswager Karstens IANR News and Photography (402) 472-3030
Department: Plant Pathology
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