EVALUATION OF VEGETABLE SOYBEAN GENOTYPES FOR RESISTANCE TO CORN-EARWORM (LEPIDOPTERA, NOCTUIDAE)

Petri dish bioassays were used to evaluate terminal foliage from 47 fi eld-grown genotypes of vegetable-type soybean, Glycine max (L.) Merril l, from maturity groups III through VIII, for resistance to corn earwo rm, Helicoverpa tea (Boddie), in 1993 and 1994. Larvae reared on ''Sat o'', IAC 100, V89-1301, V89-1563, and V88-100 had low mean weights, no t significantly different from resistant controls. However, larval wei ghts ranged from moderate to high on most vegetable-type soybeans. The most susceptible genotypes were ''Geulph'', PI 561291, and ''Rokusun' ' followed by ''Kanrich'', ''Kura'', ''Camp'', ''Wolverine'', G2246, G 4032, ''Kim, ''Hahto'', PI 561294, N2962, and D71-V89. Mortality avera ged 2.9% in 1993 and 13.5% in 1994, but was not generally useful in ev aluating resistance within maturity groups. High percent mortality and low weights of larvae reared on both resistant and susceptible genoty pes in maturity group VII/VIII in 1994 may have been related to the us e of insect-damaged foliage. Soluble leaf sugar was determined in 1994 samples and ranged from 0.50% (PI 416868-B) to 1.04% (PI561291) of dr y weight. A small but significant positive correlation (r=0.20, P=0.00 9) was found between sugar content and larval weight in maturity group s III through VI. Exceptional low larval weights in maturity groups VI I and VIII were not related to leaf sugar content.