Although the effectiveness of vegetative filter strips (VFS) for reducing herbicide runoff is well documented, a comprehensive review of the literature does not exist. The objectives of this article are to denote the methods developed for evaluating herbicide retention in VFS; ascertain the efficacy of VFS regarding abating herbicide runoff; identify parameters that affect herbicide retention in VFS; review the environmental fate of herbicides retained by VFS; and identify future research needs. The retention of herbicide runoff by VFS has been evaluated in natural rainfall, simulated rainfall, and simulated run-on experiments. Parameters affecting herbicide retention in VFS include width of VFS, area ratio, species established in the VFS, time after establishment of the VFS, antecedent moisture content, nominal herbicide inflow concentration, and herbicide properties. Generally, subsequent transport of herbicides retained by VFS is reduced relative to adjacent cultivated soil because of enhanced sorption and degradation in the former.

Field studies were conducted at Yoakum and Stephenville, TX; Jay, FL; and Midville and Plains, GA, to determine the persistence of imazapic applied to peanuts at 0, 70, 140, and 210 g ai/ha. The following year, cotton, sorghum, and corn were planted in the treated plots in Texas, cotton was planted in Florida, and corn and cotton were planted in Georgia and evaluated for carryover injury. Data collected to determine injury included plant heights and weights. In 1999 in Texas and in Florida and Georgia, there was no significant carryover injury to rotational crops from any of the imazapic rates. Data on cotton and sorghum plant height from Texas in 2000 showed height reductions for the 210-g/ha rate on cotton and the 140- and 210-g/ha rates on sorghum. These data showed no significant carryover effects to rotational crops from the 70-g/ha rate of imazapic applied to peanuts the previous year.

Spray carrier pH affects the solubility of sulfonylurea herbicides and, therefore, could affect absorption and subsequent translocation of these compounds in weeds. Trifloxysulfuron is a sulfonylurea herbicide developed for POST weed control in cotton, sugarcane, and turfgrass with a pKa of 4.81. The objective of this study was to evaluate the absorption and translocation of foliar-applied 14C-trifloxysulfuron in Palmer amaranth and Texasweed at pH 5, 7, and 9 over a period of 4 to 72 h after treatment (HAT). For absorption, effects of time, species, and pH were significant. Absorption averaged over species and pH increased logarithmically from 4 to 72 HAT. Absorption was greater for Palmer amaranth (88%) than for Texasweed (29%) when averaged over time and pH. Absorption averaged over species and time increased in the order of pH 5 (52%) < pH 9 (60%) = pH 7 (61%). Consequently, this translated into greater translocation of 14C-trifloxysulfuron in Texasweed when sprayed with the higher pH spray solutions. These data indicate that absorption and translocation of trifloxysulfuron in some weed species may be enhanced by increasing the pH of the spray solution by 2 pH units above the pKa.

Research was conducted along the Texas Gulf Coast in 1998 and 1999 to determine trifloxysulfuron soil persistence and potential injury to corn, grain sorghum, rice, and soybeans. Trifloxysulfuron was applied at 0, 7.5, and 60 g/ha to plots 0, 15, 30, 60, and 90 d prior to planting of crops. Corn and grain sorghum were more sensitive to trifloxysulfuron than rice and soybeans when planted 0 to 90 d after treatment (DAT). Trifloxysulfuron was more persistent at the San Patricio location than at Fort Bend, which had a lower soil pH. However, no phytotoxicity or plant-height reduction was observed at the four locations with corn, grain sorghum, rice, and soybeans planted 209 to 312 DAT. Greenhouse data showed that neither corn nor sunflower planted 209 to 312 DAT were adversely affected by either rate of trifloxysulfuron. Trifloxysulfuron applied to cotton up to 20 g/ha the previous year should not cause phytotoxicity to corn, grain sorghum, rice, or soybeans when grown in rotation under soil and weather conditions similar to those in these studies.

Research was conducted in 2006 and 2007 to evaluate nicosulfuron tank-mixes for field sandbur control and crop injury to ‘Tifton 85’ and ‘Jiggs’ bermudagrass. In 2006, sequential applications of nicosulfuron + metsulfuron controlled field sandbur 86 to 90% 30 d after treatment (DAT) and 77 to 85% 90 DAT. Single applications of nicosulfuron provided less than 63% control 90 DAT. In 2007, sequential applications of nicosulfuron + metsulfuron controlled field sandbur 84 to 95% 42 DAT. Injury data showed Jiggs bermudagrass was generally more sensitive to herbicide treatment than Tifton 85. Injury to Tifton 85 bermudagrass ranged from 0 to 15%, whereas injury to Jiggs was 7 to 29% 22 DAT. Forage yield data for Jiggs showed significant reductions at the first and second harvests but no differences by the third harvest. No yield reduction was noted for Tifton 85 bermudagrass from any herbicide treatment. Results of these studies indicate that nicosulfuron + metsulfuron combinations are a viable option for field sandbur control in bermudagrass pastures.