Competition of Four Morningglory(Ipomoeaspp.) Species with Cotton(Gossypium hirsutum)

Abstract

Tall morningglory [Ipomoea purpurea(L.) Roth.], pitted morningglory(I. lacunosaL.), ivyleaf morningglory [I. hederacea(L.) Jacq.] and entireleaf morningglory(I. hederaceavar.integruisculaGray) were compared for their competitive ability with cotton(Gossypium hirsutumL.) at weed densities of 4, 8, 16 and 32 weeds/15 m of row. Tall morningglory was the most competitive with yield reductions of as much as 88% at 32 weeds/15 m. The higher populations of tall morningglory also significantly reduced cotton populations, mechanical harvesting efficiency and lint percentage below that in the controls. Pitted morningglory densities twice that of tall morningglory were required to produce cotton responses similar to those induced by tall morningglory. Ivyleaf morningglory and entireleaf morningglory were almost identical in their competitive potentials and were less competitive than the other species evaluated. Their competitive ability was greatly reduced by disease. Competition from morningglories did not consistently affect cotton fiber micronaire, fiber length or strength.