plant disease and insect advisory植物病害与昆虫咨询精品.pdfVIP

Plant Disease and Insect Advisory Entomology and Plant Pathology Oklahoma State University 127 Noble Research Center Stillwater, OK 74078 Vol. 2, No. 21 Website: /Pddl/advisory.htm Nov 11, 2003 Wheat Disease Update Bob Hunger, Extension Wheat Pathologist During the past week or so I have become aware of the occurrence of several wheat diseases, including wheat leaf rust, powdery mildew, and tan spot. I have observed all of these in research plots located near Perkins Stillwater, OK. The leaf rust (Fig. 1) was on the variety Jagger, and represented a level that would be quite severe (in the 60-80 range). Remember that fall infection of leaf rust on susceptible varieties such as Jagger is quite common, but is not known to cause any major problems to the wheat. Often the infected leaves are removed by grazing, or the leaves die as freezing temperatures become more common. However, if favorable weather conditions through the winter allow the rust to overwinter, then these loci (=hotspots) of rust inoculum serve to “kick-start” the rust infections in the spring. Hence, I wouldn’t recommend trying to control the leaf rust in the fall, but I would watch the field more closely the next spring to see if the rust overwintered. This is especially true with a highly susceptible variety such as Jagger. The powdery mildew (Fig. 2) also was observed on the variety Jagger, which is highly susceptible to this disease. Basically, the things said about leaf rust in t