1a.Objectives (from AD-416):
1. Evaluate commercial and public varieties for resistance.
2. Characterize prominent pathotypes of Cercospora (C.) sojina.
1b.Approach (from AD-416):
Field and greenhouse evaluation of varieties.
Foliar diseases of soybean reduce yield by an estimated 70 million bushels annually in the United States. This estimate only takes into consideration the direct yield loss and not the additional costs associated with managing diseases with foliar-applied fungicides. Among the various foliar diseases, frogeye leaf spot is unique in that both chemical and host resistance strategies are available. However, this disease is caused by a highly variable pathogen with many races and this adds difficulty to deploying resistant varieties. Currently, fungicide resistant isolates of the frogeye leaf spot pathogen are being detected further complicating fungicide recommendations. The goal of this seven state, multi-institutional program is to develop management options for major foliar diseases of soybean. This goal will be accomplished by gaining a better understanding of the epidemiology of foliar diseases which can be used to optimize disease management strategies, identifying disease-resistant varieties, assisting in the development of resistant germplasm, and refine management recommendations based on results generated from this research. These efforts will provide immediate-term benefits and long-term solutions. The test was initiated at the Tennessee location in 2011 to screen and identify soybean lines with resistance under natural field environment. The field used for screening is well infested and has a history of good infection every year on susceptible controls. Thus there was no need to artificially inoculate the lines. The plots are also irrigated during the season. A total of 120 lines were screened and forty-five of these lines had no frogeye leaf spot symptoms. These lines however, should continue to be evaluated for the next two years to ensure that they are resistant.