Experiments were conducted in Florida in 2000 through 2003 to evaluate weed management systems in single- and twin-row peanut utilizing either conventional or strip tillage. Diclosulam or flumioxazin preemergence (PRE) or 2,4-DB or imazapic mid-postemergence (MPOST) or late-postemergence (LPOST) was needed for greater than 95% common cocklebur control in conventional- and strip-tillage peanut. In both tillage systems, paraquat + bentazon early-postemergence (EPOST) followed by (fb) 2,4-DB or imazapic MPOST, 2,4-DB or chlorimuron LPOST, or both was required for more than 80% late-season control of Florida beggarweed and control in twin-row was 5 to 10 percentage points above that observed with single-row peanut. Paraquat + bentazon EPOST preceded by a diclosulam or flumioxazin PRE or fb MPOST or LPOST applications provided 80% or greater control of ivyleaf morningglory, and no differences were observed between peanut planting pattern. Paraquat + bentazon EPOST fb imazapic MPOST was the only treatment that provided 90% or greater late-season sicklepod control across all years and tillage methods, and, regardless of tillage, sicklepod control was 7 percentage points better in twin- than single-row peanut. Treatments that contained diclosulam or flumioxazin PRE and paraquat + bentazon EPOST fb a MPOST or LPOST herbicide application increased peanut yield compared to nontreated in conventional- and strip-tillage peanut. Averaged over all herbicide treatments, years, and tillage methods, peanut seeded in twin rows yielded 300 kg/ha more than in single rows.

Research was conducted to determine the effect of planting pattern, plant density, and levels of weed management intensity on intercepted photosynthetically active radiation (IPAR), weed control, and cotton lint yield in glyphosate-resistant cotton. Twin-row planting pattern canopy IPAR was 55% 7 wk after emergence (WAE) and 76% 9 WAE compared to 48% for single-row planting pattern 7 WAE and 59% 9 WAE. Regardless of cotton density, row spacing, or weed management intensity, control of browntop millet and Florida beggarweed was at least 88% 18 WAE. Benghal dayflower, sicklepod, and smallflower morningglory control was greater in twin-rows compared to single-rows at a cotton density of 7 plants m−2. Control of Benghal dayflower and sicklepod increased when cotton density increased at low weed management intensities; however, cotton density had no effect on weed control at higher levels of weed management input. At a cotton plant density of 7 plants m−2, twin-row cotton yielded 220 kg ha−1 more than the single-row planting pattern. Data indicates twin-row cotton production is feasible and that control of various weeds was better in twin-row than single-row pattern at lower cotton density and weed management intensity.