AUGMENTATION OF SOUTHERN STEM ROT IN PEANUTS BY LARVAL FEEDING OF THELESSER CORNSTALK BORER (LEPIDOPTERA, PYRALIDAE)

Studies were done on both greenhouse- and field-grown peanuts to deter mine if feeding on the root-hypocotyl region of the plant by the lesse r cornstalk borer, Elasmopalpus lignosellus (Zeller), augments the occ urrence of southern stem rot caused by Sclerotium rolfsii Saccardo. Pe anuts were grown in the greenhouse with and without infestation with S . rolfsii sclerotia and E. lignosellus larvae. Only plants grown in so il infested with sclerotia developed southern stem rot; all plants inf ested with lesser cornstalk borer larvae were damaged at the root-hypo cotyl region. Southern stem rot incidence was consistently greatest in the plants infested with both sclerotia and larvae. In addition, less er cornstalk borer damage to the root-hypocotyl region of peanut plant s was simulated in the field for 7 consecutive weeks (treatment dates) in 1993 and for 8 weeks in 1994. Each artificially damaged plant was paired with an adjacent undamaged plant control. Fifty pairs of plants were damaged each week. Incidence of southern stem rot was assessed a t the end of the growing season and was consistently greater in damage d plants than in undamaged plants. These results indicate that damage to peanut plants, such as that caused by feeding of the lesser cornsta lk borer, increases the occurrence of southern stem rot.