Wheat stripe rust has now spread to 17 counties in Arkansas, up from nine counties last week, and with more rain and winds in the forecast, infections are likely to spread.
Desha, Faulkner, Jackson, Lawrence, Lincoln, Mississippi, Phillips and Poinsett counties join last week’s nine counties reporting the disease: Arkansas, Crittenden, Cross, Jefferson, Lee, Lonoke, Prairie, St. Francis and Woodruff counties.
“Realistically, stripe rust has probably spread throughout the Delta, even if it hasn’t been reported yet in all counties,” said Jason Kelley, Extension wheat and feed grains agronomist for the University of Arkansas Division of Agriculture. “With the strong southerly winds we have had the last few days, spores have to be spread throughout the region and points much further north – as far north as the Missouri Bootheel.
“The good news is there have been no reports of stripe rust on the western side of the state so far.”
While some varieties are more susceptible than others, “because of the unusual nature of this year’s epidemic, it would be wise to scout all fields, regardless of variety,” said Gene Milus, professor of plant pathology for the Division of Agriculture. Growers should look for hot spots of infected plants – areas where all of the plants are infected and from which spores spread to the rest of the field and beyond.
Milus said the widespread rain Thursday and forecast rain this weekend “will provide moisture for dew formation over the next couple weeks that is necessary for spores to infect plants.
“It takes about two weeks from the time of infection until stripe rust lesions are visible on the leaves. Therefore, if there are hot spots in a field, there likely will be an explosion of stripe rust across that field two to three weeks from now when new infections become evident.”
Wheat producers are being advised to apply a fungicide sooner rather than later if one or more hot spots are found in a field, Milus said.
Arkansas farmers planted 520,000 acres of winter wheat this year that will be harvested in June. Stripe rust, which normally doesn’t show until March, was spotted at the end of January this year.