BOZEMAN — Spring wheat producers throughout Montana need to monitor susceptible spring wheat varieties to look for stripe rust, says a Montana State University plant pathologist.
Jack Riesselman said that on Wednesday, the MSU Schutter Plant Disease Diagnostic Lab confirmed that fields of McNeal spring wheat in northeastern Montana had stripe rust on the flag or flag minus one leaf. If the weather remains cool and moist, the infections could develop into significant yield loss.
McNeal, Knudson and NorPro varieties are classified as very susceptible to stripe rust.
Riesselman said Ernest, Outlook, Hank and Fortuna varieties are not considered susceptible but can develop significant injury. Other commonly grown lines, including Reeder, Choteau, Freyr, Conan, Alsen and Scholar, have good or excellent stripe rust resistance. While resistant varieties can develop lesions, they generally do not have to be sprayed.
Riesselman said durum wheat is generally considered susceptible to stripe rust but that MSU has not rated durum varieties.
He said that if yield potentials are high and stripe rust is identified on susceptible wheat lines, growers should consider a fungicide application at flag-leaf emergence or early head emergence.
"Not only will these cereal fungicides arrest further stripe rust development, they will also help reduce other foliar diseases, including tan spot and leaf blotch, which are also common this year," Riesselman said.
He added that another factor for producers to consider in deciding whether to spray is the general condition of the hard red wheat crop in the United States. Many states producing hard red wheat are projecting yields well below their long term average because of drought. This could contribute to more favorable prices for Montana wheat this year.
Extension publications are searchable online at: http://www.montana.edu/publications/.