Field studies were conducted in 2000 and 2001 in Plains, GA, to determine peanut and weed response to the residual herbicides sulfentrazone, imazapic, diclosulam, and flumioxazin. Herbicide treatments included sulfentrazone applied preemergence (PRE) or preplant incorporated (PPI) at 112, 168, 224, and 280 g ai/ha, imazapic postemergence (POST) at 71 g ai/ha, diclosulam PPI at 26 g ai/ha, and flumioxazin PRE at 88 g ai/ha. Peanut exhibited early-season injury from all herbicide treatments, ranging from 0 to 10% for sulfentrazone PPI or PRE, 10% for imazapic, 3 to 23% for flumioxazin, and 1 to 7% for diclosulam. Yields were similar for sulfentrazone PPI- or PRE-treated and flumioxazin-, imazapic-, and diclosulam-treated peanut. Yellow nutsedge control was 83% or greater with all rates of sulfentrazone PRE or PPI, 83 and 90% with diclosulam, and 96 and 99% with imazapic, respectively. Flumioxazin did not control yellow nutsedge or wild poinsettia. Tall morningglory control was 82% or greater with imazapic, diclosulam, flumioxazin, and sulfentrazone PPI or PRE at 168 g/ha or higher. Florida beggarweed control was 88% or greater with diclosulam, flumioxazin, and sulfentrazone PRE at 224 and 280 g/ha. Overall, peanut tolerance to sulfentrazone at 112 to 280 g/ha PPI and PRE was high and yield was equivalent to the currently registered peanut residual herbicides.

Field studies were conducted in 2002 and 2005 to evaluate autumn vegetable tolerance to residual herbicides applied the previous spring under low-density polyethylene (LDPE) mulch. Spring applications of 1.12 kg/ha S-metolachlor, 0.027 kg/ha halosulfuron, 0.28 kg/ha sulfentrazone, and 1.12 kg/ha S-metolachlor plus 0.027 kg/ha halosulfuron were made under LDPE mulch in March of each year and included a nontreated control. After removal of the spring crop, vegetables were planted the following August. Seeded and transplanted squash, seeded cucumber, transplanted eggplant, and transplanted cabbage were evaluated. Injury to eggplant, cucumber, and transplanted and seeded squash ranged from 8 to 16% for halosulfuron, sulfentrazone, and S-metolachlor plus halosulfuron in 2002, but no injury was observed in 2005. Cabbage injury was less than 5% for any herbicide treatment either year. There were no differences for cabbage biomass for three harvests for any herbicide treatment relative to the nontreated control. Vine length for cucumber and transplanted squash was significantly reduced by sulfentrazone relative to the nontreated control. Eggplant yield for the first harvest was significantly reduced by sulfentrazone as compared with the nontreated control in 2002 but not in 2005. To avoid injury to rotational crops, growers should read all herbicide labels when considering spring herbicide applications under LDPE mulch when autumn vegetable plantings are part of their production scheme to ensure successful crop production.

Field studies were conducted to evaluate residual herbicides applied alone and with a contact weed control program in peanut in Georgia and Alabama. Residual herbicide treatments included pendimethalin preemergence (PRE) at 924 g ai/ha, diclosulam PRE at 18 and 26 g ai/ha, flumioxazin PRE at 70 and 104 g ai/ha, sulfentrazone PRE at 168 and 280 g ai/ha, and imazapic postemergence (POST) at 71 g ai/ha. All herbicides were applied alone and in combination with an early postemergence (EPOST) application of paraquat plus bentazon. Peanut injury ranged from 0 to 7% for diclosulam, from 0 to 28% for flumioxazin, from 0 to 59% for sulfentrazone, from 0 to 15% for imazapic, and from 4 to 12% for paraquat plus bentazon. Across locations and years, Florida beggarweed control was 92% or greater with flumioxazin PRE at 104 g/ha, 77% or greater with diclosulam PRE at 26 g/ha, 80% or greater with sulfentrazone PRE at 280 g/ha, ranged from 54 to 86% for imazapic POST, and was 68% or less for paraquat plus bentazon EPOST. For diclosulam, sulfentrazone, and imazapic, including paraquat plus bentazon EPOST improved Florida beggarweed control vs. these treatments alone. However, flumioxazin alone provided consistent and season-long Florida beggarweed control without paraquat plus bentazon EPOST. Sicklepod control with imazapic was consistently greater than 90%, but it was 70% or less with diclosulam, flumioxazin, and sulfentrazone. Paraquat plus bentazon EPOST used with the residual herbicide treatments resulted in variable sicklepod control ranging from 40 to 99%. Yellow nutsedge control was 95% or greater with sulfentrazone, varied from 56 to 93% with diclosulam, and was 87% or greater with imazapic. Tall and smallflower morningglory, wild poinsettia, Palmer amaranth, and bristly starbur control varied by residual herbicide treatment. Yields were similar for diclosulam, flumioxazin, sulfentrazone, and imazapic treated peanut.

Field studies were conducted to evaluate weed control in herbicide-resistant canola in Georgia. The resistant canola cultivars and respective herbicides were ‘Pioneer 45A76’ and imazamox, ‘Hyola 357RR’ and glyphosate, and ‘2573 Invigor’ and glufosinate. Weed seed of Italian ryegrass and wild radish were sown simultaneously in October with canola and control of these species was evaluated along with other naturally occurring weeds. Herbicide treatments for the respective herbicide-resistant canola cultivar were imazamox at 0.035 and 0.071 kg ai/ha, glyphosate at 0.84 and 1.64 kg ae/ha, and glufosinate at 0.5 and 1.0 kg ai/ha. Herbicides were applied at one– two-leaf (LF) and three–four-LF canola stages. There was no significant injury to any canola cultivar as a result of herbicide rate or timing of application. By midseason (February), imazamox effectively controlled wild radish, henbit, and shepherd's-purse at both rates and at both timings. When applied to three–four-LF canola, the higher rates of glyphosate and glufosinate were required to provide 75% or greater control of Italian ryegrass, wild garlic, and henbit. Glufosinate did not adequately control wild radish at either rate or application timing. Greenhouse experiments provided similar results.