Search Results

You are looking at 1 - 4 of 4 items for

  • Author or Editor: David C. Bridges x
Clear All Modify Search
Free access

Timothy L. Grey, David C. Bridges and D. Scott NeSmith

Field studies were conducted in 1993, 1994, and 1996 to determine the tolerance of several cultivars of zucchini and yellow crookneck squash (Cucurbita pepo L.) to various rates and methods of application of clomazone, ethalfluralin, and pendimethalin. Applying herbicides preplant soil incorporated (PPI), preemergence (PRE), at seedling emergence (SE), or early postemergence (EPOT) resulted in plant injury that varied from 0% to 98%. Ethalfluralin and pendimethalin (PPI) at 1.12 kg·ha–1 a.i. resulted in the greatest stand and yield reductions across all cultivars. Fruit number and weight declined for all cultivars in 1993 and 1994 as the amount of pendimethalin applied PRE was increased. Zucchini (`Senator') fruit size was significantly reduced for the first three harvests in 1993 by PRE application of pendimethalin or PPI application of ethalfluralin, at all rates. Yellow squash (`Dixie') fruit size was unaffected by herbicide treatment for any harvests during 1993 or 1996. Yellow and zucchini squash yield, fruit number, and average fruit weight were equal to, or greater than, those of the untreated control for PRE clomazone using either the emulsifiable concentrate formulation (EC) during 1993, 1994, and 1996 or the microencapsulated formulation (ME) during 1996. Foliar bleaching and stunting by clomazone was evident in early-season visual observations and ratings, but the effect was transient. Foliar bleaching by clomazone PPI (1.12 kg·ha–1 a.i.) was more evident in `Senator' zucchini, and yield was significantly reduced in 1993. These effects of clomazone PPI were not evident in 1994 for either `Elite' or `Senator' zucchini squash. Chemical names used: 2-[(2-chlorophenyl)methyl]-4, 4-dimethyl-3-isoxazolidinone (clomazone); N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine (ethalfluralin); N-(1-ethylopropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

Free access

Timothy L. Grey, David C. Bridges and D. Scott NeSmith

Field studies were conducted in 1993, 1994, and 1995 to determine tolerance of seeded and transplanted watermelon [Citrullus lanatus (Thunb.) Matsum and Nak.] to clomazone, ethalfluralin, and pendimethalin using method of stand establishment (directseeded vs. transplanted) and time of herbicide application [preplant soil incorporated (PPI), preplant to the surface (PP), or postplant to the surface (POP)] as variables. Yield and average fruit weight in plots with clomazone were equal to or greater than those in control plots for the 3-year study regardless of method of application. Bleaching and stunting were evident with clomazone in early-season ratings, but injury was transient and did not affect quality or yield. Of the three herbicides, ethalfluralin PPI resulted in the greatest injury, stand reduction, and yield reduction of the three herbicides. Pendimethalin (PPI, PP, or POP) reduced yield of direct-seeded but not of transplanted watermelon. Chemical names used: 2-[(-2-chlorophenyl)methyl]-4, 4-dimethyl-3-isoxazolidinone (clomazone); N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl) benzenamine (ethalfluralin); N-(1-ethylopropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

Free access

Timothy L. Grey, David C. Bridges and D. Scott NeSmith

Field studies were conducted to evaluate the tolerance of several pepper (Capsicum annuum L.) cultivars to the herbicide clomazone. Peppers tested included the bell cultivars Yolo Wonder and Jupiter; the banana cultivar Sweet Banana; and the pungent cultivars Jalapeno and Red Chili. Treatments were clomazone at 0.56 or 1.12 kg·ha-1 a.i. applied either preplant incorporated (PPI), pretransplant (PRE-T), or posttransplant (POS-T) on the day of transplanting, plus a nontreated control. Clomazone at 1.12 kg·ha-1 a.i. PPI and PRE-T significantly injured (bleaching or chlorosis of foliage) `Sweet Banana' (40% and 20%, respectively) and `Red Chili' (30% and 18%, respectively) in 1993 in early-season evaluations, but this injury was transient and did not significantly affect total fruit number or yield. Injury to any cultivar from POS-T clomazone at 0.56 and 1.12 kg·ha-1 a.i. was nonsignificant. Overall, tolerance to clomazone was excellent for all treatments and across all cultivars. Yield was not reduced significantly by any treatment. Chemical names used: 2-[(2-chlorophenyl) methyl]-4, 4-dimethyl-3-isoxazolidinone (clomazone).

Free access

Timothy L. Grey, David C. Bridges, Paul Raymer, Don Day and D. Scott NeSmith

Field studies were conducted to determine the tolerance of 11 sweet corn (Zea mays L.) cultivars to the herbicides nicosulfuron and primisulfuron. The su cultivar `Merit' was intolerant of nicosulfuron and primisulfuron, as indicated by significant differences from the untreated check for all measured variables. Most other su cultivars exhibited stunting, but injury was ≤19% (0% = no injury; 100% = dead) with nicosulfuron and primisulfuron in 1992. The se cultivars Alpine and Harris Moran Silverado exhibited variable stunting to nicosulfuron (25% and 23% injury, respectively) and primisulfuron (43% and 50%, respectively) in 1992. The sh2 cultivar Supersweet Jubilee was injured less by nicosulfuron (16%) than by primisulfuron (33%) in 1992. All cultivars except Merit recovered from early-season herbicide injury in 1992 and 1993. Significant differences among the se, su, and sh2 cultivars were recorded for the remaining variables (stalk height, marketable ear number and yield, ear length and diameter), but no patterns with respect to a specific sugary genetic background developed in 1992 or 1993. Nicosulfuron and primisulfuron were safely applied to the cultivars Alpine, Harris Moran Silverado, Royal Gold, Seneca Chief, Calumet, Jubilee, and Supersweet Jubilee without reductions in fresh ear yield. Chemical names used: {2-[[[[(4,6-dimethoxy-2-pyrimidinyl)amino] carbonyl]amino]sulfonyl]-N,N-dimethyl-3-pyridinecarboxamide} (nicosulfuron); {methyl 2[[[[[4,6-bis(difluoromethoxy)-2-pyrimidinyl]amino]carbonyl]amino]sulfonyl]benzonate} (primisulfuron).