Effects of Temperature on Competition Between Heterodera glycines and Pratylenchus scribneri on Soybean

Abstract

Population development of Heterodera glycines and Pratylenchus scribneri, alone and in combination, at various initial levels on soybean (Glycine max) in 70 days at 20, 24, 28, and 32 C was determined in two experiments. Following preliminary 5-day exposure of infested soil at 22 C, population increase of H. glycines was not affected by the presence of P scribneri at any subsequent temperature. With an initial 5-day exposure at 28 C, increase of H. glycines was suppressed at 20, 24, and 32 C, when 1 000 second-stage juveniles were coinoculated with 5 000 P scribneri. Populations of P scribneri were not affected significantly by concomitant root infections with H. glycines, regardless of temperature. Final male:female ratios of H. glycines increased with increasing temperature up to 28 C in both experiments. In the first experiment, the male:female ratio was highest for H. glycines in combination with an initial population of either 2 000 or 3 000 P. scribneri, but the ratio in the se