Response of Cotton to Damage by Tobacco Budworm (Lepidoptera: Noctuidae): Changes in Fruit Distribution

In 1987 and 1989, cotton, Gossypium hirsutum L., plants at different developmental stages were artificially infested with five neonate tobacco budworm, Heliothis virescens (F.), larvae per plant. The position of each open boll on the plant was recorded at harvest. Infestations, regardless of the developmental stage of the plant, reduced boll numbers at the first fruiting position on the branch. Boll distributions at position 1 on plants infested at the 5th-node stage of growth were similar to plants infested at the 15th-node stage. However, plants infested at the 15th-node stage set a greater number of bolls at position 2 than plants infested at the 5th-node stage. Only plants infested at the 5th-node stage had fewer total bolls than the control. DES-119, an earlymaturing cotton, produced more bolls at positions 1 and 2 on the lower nodes than ST-825 when plants were infested at the 7th-node stage of growth. When plants were infested at the 12th-node stage, DES-119 produced more bolls at position 1 on the lower nodes, whereas ST-825 produced more on the upper nodes. There was no varietal difference in boll production at position 2 of plants infested at the 12th-node stage.