Lincoln, Nebraska
March 23, 2005
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 at
http://ianrpubs.unl.edu/plantdisease/g1245.htm or
Nebraska Cooperative Extension NebFact NF02-559, Wheat
Disease Fact Sheet No. 1 Management Program for Rust
Diseases of Wheat, at
http://ianrpubs.unl.edu/plantdisease/nf559.htm.
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 at
http://cropwatch.unl.edu/. |