Published online by Cambridge University Press: 12 June 2017
Experiments with similar experimental design, soil, and planting date were conducted between 1975 and 1979 to evaluate the interference of jimsonweed on soybeans and cotton in Alabama (AL), Arkansas (AR), and Mississippi (MS). Jimsonweed densities were 0, 4, 8, 16, 32, and 64 plants 12 m−1 of row. Because of variation in rainfall patterns, geographic region influenced jimsonweed interference in cotton but not in soybeans. Even though jimsonweed interference was reduced by lack of rainfall, jimsonweed was more competitive in the less competitive cotton than in soybeans. Jimsonweed at 64 plants 12 m−1 of row was more competitive with cotton than soybeans, causing a 56 and 16% yield reduction, respectively. Position of jimsonweed to the soybean row did not influence competitiveness. Interspecific interference with soybeans caused one-third more reduction in jimsonweed fresh weight and capsules per plant than interspecific interference with cotton. The potential for jimsonweed to become a problem in southern soybeans is less than its potential in cotton because of the competitive ability of soybeans to reduce the growth and reproductive potential of jimsonweed.