| Abstract/Contents: | "Combination products including quinclorac, sulfentrazone, and/or traditional broadleaf herbicides (2, 4-D, dicamba, MCPP) have recently become available for weed control in turfgrass. Such products include Q-4 (quinclorac, sulfentrazone, 2, 4-D, and dicamba; PBI Gordon, St. Louis, MO) and Surge (sulfentrazone, 2, 4-D, MCPP, and dicamba; PBI Gordon, St. Louis, MO). Combination herbicides could be beneficial because they may conceivably control crabgrass (quinclorac), sedges (sulfentrazone), and broadleaf weeds (traditional broadleaf weed control products) with a single herbicide product. When applied alone, these herbicides are safe on bermudagrass (Cynodon dactylon). However, injury has been observed from these combination products. Research was conducted to evaluate Ferromec (PBI Gordon, St. Louis, MO), a liquid nitrogen fertilizer containing iron and sulfur, as a potential safening agent when applying combination products such as Q-4 and Surge. Research was also conducted to evaluate long term weed control of selected combination herbicides including Speedzone (carfentrazone, 2, 4-D, mecoprop, dicamba; PBI Gordon, St. Louis, MO), Speedzone Southern (carfentrazone, 2, 4-D, mecoprop, dicamba; PBI Gordon, St. Louis, MO), Confront (triclopyr, clopyralid; Dow AgroSciences, Indianapolis, IN), and Trimec Classic (2, 4-D, mecoprop, dicamba; PBI Gordon, St. Louis, MO). Research was conducted at the East Tennessee Research and Education Center - Plant Sciences Unit in Knoxville, TN. Four bermudagrass cultivars, "Tifway" (C. dactylon x C. transvaalensis), "Yukon" (C. dactylon), "Riviera" (C. dactylon), and "LaPaloma" (C. dactylon) were evaluated for tolerance to herbicide treatments during August 2007. Treatments included Q-4 at 1.7 kg ai/ha (8 pt/a) and 3.5 kg/ha (16 pt/a), Q-4 at 1.7 kg/ha (8 pt/a) plus Ferromec at 2.93 kg/ha (13.6 pt/a), quinclorac (Drive; BASF, Florham Park, NJ) at 1.12 kg/ha (1 lb/a) plus methylated seed oil at 1.8 L/ha (1.5 pt/a), Surge at 1.2 kg/ha (4 pt/a), and Surge at 1.2 kg/ha (4 pt/a) plus Ferromec at 2.9 kg/ha (13.6 pt/a). Each treatment was replicated 3 times in a randomized complete block design. Experimental units were 1.52 by 1.52 meters (5 by 5 feet). An additional trial was conducted to evaluate long term control of buckhorn plantain (Plantago lanceolata) and common dandelion (Taxacum officinale) with selected combination herbicides with applications made on March 7, 2006. Treatments included Speedzone at 1.23 kg/ha (4 pt/a), Surge at 1.22 kg/ha (4 pt/a), Speedzone Southern at 0.57 kg/ha (5 pt/a), Confront at 0.84 kg/ha (2 pt/a), and Trimec Classic at 0.67 kg/ha (1.75 pt/a). Each treatment was replicated 3 times in a randomized complete block design. Experimental units were 1.52 by 3.05 meters (5 by 10 feet). Herbicides were applied in a water carrier volume of 280 L/ha (30 GPA) with a CO2 pressurized sprayer and a 101.6 cm (40 inch) boom with a pressure of 125 kPa (18 PSI) and 8002 flat fan nozzles. Turf injury and weed control were evaluated visually on a scale of 0 to 100% (0 = no turfgrass injury or weed control; 100 = complete plant death). Injury >=20% and weed control <80% was deemed unacceptable. Q-4 (1.7 kg/ha) injured all bermudagrass cultivars <=22% 7 days after treatment (DAT). The addition of Ferromec (2.9 kg/ ha) to Q-4 did not reduce injury to Yukon and Tifway, but did reduce injury to LaPaloma and Riviera to <=8%. Surge (1.2 kg/ha) injured all bermudagrass cultivars <=20% 7 DAT. Ferromec did not reduce Surge injury except to LaPaloma 7 DAT. Q-4 plus Ferromec reduced injury to the Riviera, LaPaloma, and Yukon cultivars compared to Q-4 alone 14 DAT. However, there was no reduced bermudagrass cultivar injury due to Surge plus Ferromec compared to Surge alone 14 DAT. No injury was observed 21 DAT for any treatment and/or cultivar. These data indicate Ferromec can reduce injury from Q-4 and Surge to some bermudagrass cultivars. However, injury reduction was not consistent across cultivars; and it is likely that environmental conditions such as temperature, humidity, and soil moisture affect injury development. Future research could evaluate additional nitrogen, iron, and sulfur combinations and the potential benefit of other micronutrients. All combination herbicides controlled buckhorn plantain >=88% 184 DAT. Surge and Confront controlled common dandelion >=66% 345 DAT, but control was <=26% with all other treatments. These data indicate all evaluated combination products provide acceptable long-term control of buckhorn plantain; however, Surge and Confront provided greater long-term control of common dandelion." |
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