Wheat Rust Alert
While many wheat fields in Colorado's High plains are still rust free. We are beginning to pick up a few reports of stripe
rust sightings.
On Monday, Brett Mermis, Servi-Tech Agronomist reported finding stripe rust in fields near Eckley Colorado.
This morning, Ron Meyer, CSU Extension Agronomist, Burlington confirmed stripe rust near Stratton.
Stripe rust has also been found in the Nebraska Panhandle near Chappell.
There aren't a lot of sightings but... with cooler and wetter weather, we're probably on the verge of seing a lot in our
wheat fields, especially with susceptible wheat varieties.
Drew Lyon, Nebraska Panhandle Extension Cropping Systems Specialist says:
"...producers should be keeping a close eye on their fields, particularly irrigated fields. Treatment may even
be economically viable for some dryland fields... Even though wheat prices are rather low, the wheat crop
has some excellent yield potential due to the good moisture so far this spring.
Based on the amount of stripe rust developing in some Nebraska fields and the continued rains, growers
should consider spraying to protect the flag leaf and potential yield. Stripe rust can cause 100% loss to a
wheat crop."
Stripe rust will spread most readily in 50 to 60 degree temperatures especially during wet or rainy weather. The disease
spread is still likely up to 65 degrees and is possible at 70 degrees. Windblown spores will germinate at night when the
temperatures and leaf moisture conditions are right.
Spore formation is stopped when daytime temperatures exceed 80 degrees.
All treatments are preventative and none are very good at curing stripe rust infections. It is therefore very important to
apply stripe rust fungicides before the first sign of infection. In previous years, the timing between first signs of the rust
and widespread infection were only two days.
Finally, CSU and other University research on rust fungicides have not found any benefits from treatments in the
absence of rust.
Susceptible wheat varieities under irrigation are the most at risk. There has been no evidence that the rust we're now
getting will significantly impact resistant wheat varieties. The 2009 Wheat Decisions handbook includes variety
information on stripe rust susceptibility or resistance:
http://www.extsoilcrop.colostate.edu/CropVar/documents/winterwheat/wheatreport_2009.pdf
For more information check Kansas State's stripe rust fact sheet at:
http://www.ksre.ksu.edu/path-ext/factSheets/Wheat/Wheat%20Stripe%20Rust.asp
Carefully consider your decision on whether to apply rust fungicides. Don't deliberate too long though.
Sincerely,
Bruce Bosley