Economic assessment of weed management in strip- and conventional-tillage nontransgenic and transgenic cotton.

摘要

Studies were conducted to evaluate weed management systems in nontransgenic, bromoxynil-resistant, and glyphosate-resistant cotton (Gossypium hirsutum) in strip- and conventional-tillage environments. Tillage did not affect weed control, cotton lint yields, or net returns. Early season stunting in strip-tillage cotton was 5% or less, regardless of herbicide system or cultivar and was transient. Excellent (>90%) control of common lambsquarters (Chenopodium album), common ragweed (Ambrosia artemisiifolia), and Ipomoea species, including entireleaf (Ipomoea hederacea [Pharbitis hederacea] var. integriuscula), ivyleaf (Ipomoea hederacea), pitted (Ipomoea lacunosa) and tall morningglories (Ipomoea purpurea [Pharbitis purpurea]), Jimsonweed (Datura stramonium), prickly sida (Sida spinosa), and velvetleaf (Abutilon theophrasti), was achieved with systems containing bromoxynil, glyphosate, and pyrithiobac early postemergence (EPOST). Glyphosate systems provided better and more consistent control of fall panicum (Panicum dichotomiflorum) and large crabgrass (Digitaria sanguinalis) than bromoxynil and pyrithiobac systems. Bromoxynil and pyrithiobac EPOST did not control sicklepod unless applied in mixture with MSMA and followed by (fb) a late postemergence-directed (LAYBY) treatment of prometryn plus MSMA. Palmer amaranth (Amaranthus palmeri) was controlled (>90%) with all glyphosate and pyrithiobac systems and with the bromoxynil system that included a broadcast soil-applied herbicide treatment. Bromoxynil systems without a broadcast soil-applied herbicide treatment controlled Palmer amaranth 87% or less. Herbicide systems that included glyphosate EPOST controlled sicklepod (Senna obtusifolia [Cassia obtusifolia]) with or without a soil-applied herbicide treatment. The highest yielding cotton included all the glyphosate systems and bromoxynil systems that contained a soil-applied herbicide treatment. Non-transgenic systems that included a soil-applied herbicide treatment yielded less than a system with soil-applied treatment plus glyphosate EPOST. Net returns from glyphosate systems were generally higher than net returns from bromoxynil or pyrithiobac systems..