?Significant developments in the status of leaf rust? have occurred in recent days, according to Erick DeWolf, assistant professor of plant pathology at Kansas State University.
Reports from Texas indicate the leaf rust is now approaching 20 percent severity on susceptible wheat varieties fields located near San Antonio, and that the disease was also present at low to moderate levels north of Dallas near the Oklahoma border.
Stripe rust was also detected at trace levels in this same area.
?We also continue to find evidence that leaf rust has successfully overwintered in parts of central, south central and northeast Kansas this year,? DeWolf said.
The most recent detections of leaf rust in Kansas come from Barber and Riley counties.
?The Barber County detection of leaf rust was in a field of Jagger located near the city of Hazelton, about 15 miles north of the Oklahoma border,? DeWolf said. ?The disease was only detected on the most mature wheat, and most fields appear to be disease free at this point.?
Leaf rust had previously been detected in wheat fields in Rice, Ellsworth and Riley counties. DeWolf said evaluation of fields near Manhattan indicates the incidence of leaf rust has increased over the past two weeks. At all locations, the leaf rust was limited to the lower canopy, but was actively producing spores.
?Rain in central and northeast Kansas have resulted in an environment that is conducive for the further establishment of the leaf rust,? DeWolf said.
?The wheat in many areas of the state is slightly behind normal growth and development because of cool spring temperatures. There are no reports of leaf rust in western Kansas to date.?
The top three wheat varieties in the state?Jagalene, Overley and Jagger?are known to be susceptible to leaf rust.
?The susceptibility of these varieties, the apparent overwintering of leaf rust, increasing leaf rust pressure in Texas and delay in crop maturity all increase the risk of severe disease in Kansas this year,? DeWolf said.
No immediate management actions are necessary, but growers should monitor the leaf rust situation carefully during the next few weeks.
?Research has demonstrated the most effective time to apply a foliar fungicide to wheat is between flag leaf emergence through heading,? DeWolf said. ?The average yield response for foliar fungicides in Kansas is 10 percent.
Wheat prices have fallen slightly this past week, but are still around $9 bushel. The costs of fungicides have also increased recently with the average cost now approaching $25 per acre for product plus application costs.
?Fields planted to susceptible varieties, and a yield potential of more than 35 bushels per acre are strong candidates for a fungicide application this year,? DeWolf said.