06/06/08 Late blight recommendations; stripe rust update

Washington Ag June 6, 2008 While potato late blight has been found in western Washington this spring it has not yet been reported in the Columbia Basin this season. Washington State University plant pathologist Dennis Johnson says the probability of late blight occurring in the basin is between 80 and 90 percent and recent weather has been favorable for the disease. Johnson has this recommendation on the Late Blight Hotline. Johnson: "Fields where foliage has closed between rows and all fields near fields that had late blight in them last year, should be treated with a late blight fungicide within the next six days." That recommendation was issued June 5th. Johnson says fields should be checked for late blight at least twice a week. Xianming Chen with the Agricultural Research Service at Pullman says with current weather conditions and those forecast for the next two weeks stripe rust will increase in most wheat growing areas east of the Cascades. He says fields grown with susceptible cultivars should be checked often and when stripe rust develops to five percent of severity and incidence a fungicide application should be considered. Chen says stripe rust is almost absent in many fields in the Horse Heaven Hills area thanks to fungicide applications made in April and that has helped keep the rust inoculum at a low level. I'm Bob Hoff.