Experiments were conducted in 1998 and 1999 at the Central Crops Research Station near Clayton, NC, to evaluate density-dependent effects of Datura stramonium on weed growth and seed rain and Gossypium hirsutum growth and yield. Datura stramonium height was not affected by density in either year. Crop height never exceeded weed height during the growing season, indicating that competition for light occurred between the two species. Eight weeks after planting or later, G. hirsutum height decreased as D. stramonium density increased. An increase in D. stramonium density from 1 to 32 plants (9.1 m of row)−1 resulted in a decrease in capsule production per plant of 92 and 60 in 1998 and 1999, respectively. Total D. stramonium dry weight per 9.1 m of row increased via a quadratic relationship as weed density increased. Gossypium hirsutum lint yields decreased as D. stramonium biomass and density increased in both years. Estimated yield losses of 10 and 25% were caused by D. stramonium at 0.5 and 1.5 p...

Datura stramonium interference and seed rain in Gossypium hirsutum.

Studies were conducted to determine whether glufosinate treatments to glufosinate-resistant cotton caused changes in floral morphology, pollen viability, and seed set. Four glufosinate treatments were included: (1) glufosinate applied postemergence over the top (POST) at the four-leaf stage, (2) glufosinate applied POST at the eight-leaf stage, (3) the first two treatments sequentially, and (4) a POST application at the four-leaf stage followed by (fb) a postemergence-directed stem application (PDS) at the eight-leaf stage. Glufosinate was consistently applied at 0.49 kg ai/ha. A nontreated control was included. Glufosinate treatments did not affect stigma height, length of the staminal column, or pollen viability. However, the distance from the top anther to the tip of the stigma was less in plants treated with an eight-leaf POST treatment than in nontreated plants, although this difference is not likely to influence pollen deposition because in both cases anthers reached above the stigma tip. Plants rec...

Glufosinate Does Not Affect Floral Morphology and Pollen Viability in Glufosinate-Resistant Cotton

Interference and seed-rain dynamics of four polygonum species in cotton.

ABSTRACT Studies were conducted to evaluate weed management programs in non-transgenic, Buctrilresistant, and Roundup-resistant cotton in no-tillage and conventional-tillage environments. Tillage did not affect the level of weed control provided by herbicides evaluated. Early season stunting in no-tillage cotton was 3% regardless of herbicide system and was transient. Conventionally tilled cotton yielded 17% more on average than no-tillage cotton. Excellent (> 90%) velvetleaf, common lambsquarters, jimsonweed, Ipomoea morningglory spp., and prickly sida control was achieved with programs containing Staple, Buctril, and Roundup. Residual herbicide inputs were necessary for adequate large crabgrass and goosegrass control. Buctril and Staple postemergence did not control sicklepod unless supplemented with MSMA and followed by a late post-directed treatment of Bladex plus MSMA. Herbicide programs that included Roundup controlled sicklepod regardless of late postemergence-directed treatment. When Cotoran applied preemergence was included in Buctril programs, net returns were at least $375 A and not different from the higher-yielding programs in non-transgenic cotton. Late-season weed control was usually greater than 90% from Roundup programs and net returns from Roundup programs were as high or higher than net returns from programs that utilized mid-season treatments of Buctril, Staple, or Cotoran plus MSMA.

Scott Gh

Papers

Interference and seed-rain dynamics of four polygonum species in cotton.

Economic assessment of weed management for transgenic and non-transgenic cotton (Gossypium hirsutum) in conventional and no tillage systems.