干旱区生态环境知识资源中心

Three planting-date windows [early - 3 weeks before (i.e., 26-29 April) the recommended optimum planting window; timely the commonly recommended optimum planting window of 16-19 May; and late - 3 weeks after (i.e., 6-9 June) the recommended optimum planting window] and three planting patterns (Solid solid-row stand; Skip 2x1 - two rows planted, one row skipped; and Skip 2x2 - two rows planted, two rows skipped) were evaluated to determine their influence on abundance and population dynamics of arthropods during 3 years in cotton, Gossypium hirsutum L., on the Texas Rolling Plains. Arthropod species sampled included thrips, Frankliniella occidentalis (Pergande); cotton fleahopper, Pseudatomoscelis seriatus (Reuter); cotton aphid, Aphis gossypii Glover; and bollworm, Helicoverpa zea (Boddie). Planting date significantly influenced aphid abundance. Fewer aphids were found in early-planted cotton (1.0 per leaf) compared with timely (2.3 per leaf) or late (1.8 per leaf) planted cotton. Similarly, bollworms were more abundant in early-and late-planted cotton (157 and 204% greater, respectively) than in optimally planted cotton. Planting pattern did not significantly influence abundance of thrips or cotton fleahopper. Conversely, consistently more cotton aphids (2.2 per leaf) were found in Skip 2x2 planted cotton, followed by Skip 2x1 (1.8 aphids per leaf) and Solid (1.2 aphids per leaf). Abundance of bollworms did not significantly vary with planting pattern. With fewer planted rows, Skip 2x2 yield, at 348 kg per hectare, was significantly less than that of Skip 2x1 (414 kg per hectare) or Solid (409 kg per hectare), yet marked improvement in most lint-quality parameters was noted for both skip-row plantings. This study provides evidence that a Skip 2x1 planting pattern in mid-May seems to be the best production scenario for dryland cotton in the semi-arid region of Texas.