Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2006
Publication Date: 12/20/2006
Citation: Brenneman, T.B., Culbreath, A.K., Holbrook Jr, C.C. 2006. Evaluation of peanut cultivars for resistance to Rhizoctonia limb rot. Proc. Amer. Peanut Res. and Educ. Soc. 38:22. Interpretive Summary: not required
Technical Abstract: Rhizoctonia limb rot, caused by Rhizoctonia solani AG-4, is a disease of major importance to peanut growers in the southeastern United States. Since the disease is difficult to reproduce in the greenhouse, and in the field it is often confounded by the presence of other diseases, the amount of yield loss and susceptibility of many currently grown cultivars is not well documented. Paired field plots either inoculated with R. solani (infested oat seed inoculum) or noninoculated were established in 2000-2002 with the noninoculated plots also sprayed with thifluzamide to control soilborne diseases. Severe limb rot developed in 2000, and the average yield reduction across cultivars was 943 lb/A. 1112001 and 2002 disease levels were lower and yield losses were 659 and 714 lb/A, respectively. Georgia Green averaged 5397 and 4546 lb/A for the rioninoculated and inoculated plots, respectively. In 2004 and 2005, similar plots evaluating only late season cultivars were established in a field fumigated each spring with methyl bromide. Yields were generally lower but good disease epidemics developed. GA-O1R had the least yield loss and highest yield in inoculated plots (4258 lb/A). Inoculated plots of Tifrunner, DP-1, C-99, Hull, and GA-02C all yielded less than 3900 lb/A, and except (iA-02C were more than 600 lb/A less than noninoculated plots. There are differences in susceptibility to limb rot among peanut cultivars, and field inoculations in the absence of other diseases is an effective way to evaluate it. Such studies also illustrate that losses in excess of 1000 lb/A are possible from this disease.