Aggressiveness of Sclerotinia minor and S. sclerotiorum on Runner Peanut

摘要

Sclerotinia blight caused by Sclerotinia minor and S. sclerotiorum were recently reported on peanut in Arkansas. Currently, there is little information on the aggressiveness of these species on runner peanut. Inoculum used in these experiments was an agar plug collected from a culture that was actively growing on PDA. Runner peanut cultivars consisted of 'Georgia 09B' 'Georgia 06G'and 'FloRun 107'. Because S. sclerotiorum is the causal agent of white mold of soybean, three soybean cultivars were included in this study. Six-wk-old peanut plants were inoculated on the main stem, while soybean seedlings at V1 growth stage were inoculated on a cotyledonary leaf. Inoculated plants were incubated for six days in a humidity chamber. Percent infection on peanut was 85% for S. minor and 33% for S. sclerotiorum. In soybean, S. minor caused 30% infection, whereas S. sclerotiorum caused 75%. Of the infected plants, S. minor produced a 50% greater lesion on peanut compared to that of S. sclerotiorum; however, in soybean, S. sclerotiorum caused a 50% greater lesion compared to that of S. minor. In this study, Sclerotinia minor was the more aggressive species on peanut, which supports field observations and suggests that between species, S. minor is of a greater concern for peanut production in Arkansas.