Source: Erick DeWolf, Extension Plant Pathology, Kansas State University
Stripe rust remains a significant threat in Kansas. Parts of south central and southwest Kansas near the Oklahoma border have been extremely dry this spring and many growers in those areas are reporting thin stands and expect below-average yields. As one progresses north into central Kansas, the optimism about crop yields improves. The growth stage of the wheat in this area is highly variable, with most fields in the early stages of grain development — although a few fields have just completed flowering. Stripe rust could be easily found on the flag leaves in most fields this week in these areas. The incidence of disease on these upper leaves ranged from trace to more than 20 percent. Severity is generally less than 10 percent at the current time.
Reports from northeast, north central and northwest Kansas indicate that stripe rust is very active in these regions of the state. I have received a small number of reports of severe stripe rust in fields in north central and northwest Kansas. Severity of stripe rust in these problem fields exceeds 30 percent. The wheat in this area of the state has been heading or flowering this week. Stripe rust is likely to cause severe yield loss in northern Kansas, and many growers have attempted to reduce potential losses with fungicides.
Nearly all varieties with Jagger in the pedigree appear to be moderately or highly susceptible to stripe rust now. Preliminary observations suggest that Jagger, Jagalene, Fuller, Jackpot, PostRock, Santa Fe, Hitch, Smoky Hill, Shocker, Danby, Art, Overley, Protection, and Hawken should be considered vulnerable to stripe rust.
Some varieties with known susceptibility are also affected, including: TAM 112, 2137, Above and Ripper.
Varieties that appear to have moderate or high levels of resistance to the new races of stripe rust include TAM 111, Armour, Aspen and Hatcher. TAM 111 is very popular in western Kansas and this resistance should help reduce the potential yield losses in this region.
Only low levels of leaf rust have been observed in Kansas to date. There are no reports of stem rust.