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Makhan S. Bhullar, Simerjeet Kaur, Tarundeep Kaur and Amit J. Jhala

using graminicides. Hence, weed management programs in potato usually include at least one herbicide application and a mechanical operation in Punjab. Potato growers in northwest India rely on triazine herbicides for weed control. Atrazine, a triazine

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Jayesh B. Samtani, John B. Masiunas and James E. Appleby

acetochlor + atrazine or s-metolachlor at the leaf unfolding stage. This article investigates more chloroacetanilide herbicides; determines if atrazine contributes to leaf tatters injury; and compares white and northern red oak injury ( Quercus rubra L

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J.L. Nus and M.A. Sandburg

Throughout the north-south climatic transition zone of the eastern United States, cool- and warm-season turfgrasses are used adjacently. A greenhouse study with creeping bentgrass (Agrostis palustris Huds.) was initiated to determine threshold concentrations of atrazine, an effective pre- and postemergence herbicide for warm-season turfgrasses, that would result in unacceptable levels of phytotoxicity to seedling and mature creeping bentgrass. Mature and 8-week-old seedling `Penncross' creeping bentgrass were given 6.5 mm of daily irrigation of untreated water or water containing atrazine at 0.01, 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, 1.28, or 2.56 mg·liter-1. A model of quality ratings taken 20 days after the initiation of treatments indicated threshold concentrations resulting in unacceptable turf quality to be approximately 0.05 and 0.08 mg·liter-1 for seedling and mature bentgrass, respectively. Chemical name used: 2-chloro-4-ethylamino-5-isopropylamino-s-triazine (atrazine).

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William E. Klingeman, Gregory R. Armel, Henry P. Wilson, Thomas E. Hines, Jose J. Vargas and Philip C. Flanagan

., 2008 ). For example, POST mixtures of reduced rates of the PSII inhibitor atrazine plus mesotrione has enhanced management of larger and more difficult to control weed species, including nutsedge ( Cyperus sp.) and canada thistle ( Cirsium arvense

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Jayesh B. Samtani, John B. Masiunas and James E. Appleby

[ Glycine max (L.) Merr.] planting or postemergence applications of glyphosate. Based on these observations, we theorized that leaf tatters was caused by drift from herbicide applications before or at corn planting. Atrazine, glyphosate, s

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C. Wilson, T. Whitwell and S. Klaine

Atrazine, simazine, and metalaxyl residues are often present in sprayer rinsates and in runoff water following application of the formulated products. As an initial step in the development of a constructed wetland for the phytoremediation of these pesticides in water, several plant species were evaluated for their tolerances to each. Plant species were chosen based on their aesthetics, tolerance to wetland conditions, and their potential to produce much vegetative growth. Species included: Acorus gramenius, Canna hybrida `King Humbert', Myriophyllum aquaticum, and Pontederia cordata. Plants were exposed to various concentrations of each pesticide dissolved in 10% Hoagland's nutrient media for 7 days. Tests were conducted under metal halide lamps with a light intensity of 400 μmol/m2 per s and a photoperiod of 16 h light: 8 h dark. Test endpoints measured included 7-day fresh mass production and chlorophyll fluorescence. A completely randomized statistical design with four replications of each concentration was utilized for each plant species. These tests indicate that all plant species were susceptible to atrazine and simazine in the 0.1 to 1 μg/ml range. Effected plants displayed concentration-dependent degrees of chlorosis and necrosis. Plants were more tolerant to metalaxyl concentrations in water. However, leaf chlorosis and necrosis did occur at concentrations greater than 25 μg/ml. Future research will quantify the uptake and mineralization potential for these plants and pesticides.

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Lambert B. McCarty, D. Wayne Porter, Daniel L. Colvin, Donn G. Shilling and David W. Hall

Greenhouse studies were conducted at the Univ. of Florida to evaluate the effects of preemergence herbicides on St. Augustinegrass [Stenotaphrum secundatum (Walt.) Kuntze] rooting. Metolachlor, atrazine, metolachlor + atrazine, isoxahen, pendimethalin, dithiopyr, and oxadiazon were applied to soil columns followed by placement of St. Augustinegrass sod on the treated soil. Root elongation and biomass were measured following application. Plants treated with dithiopyr and pendimethalin had no measurable root elongation and root biomass was severely (>70%) reduced at the study's conclusion (33 days). Root biomass was unaffected following isoxaben and oxadiazon treatments, but oxadiazon applied at 3.4 kg·ha-1 reduced root length by 50%. Atrazine at 2.2 kg·ha-1 and metolachlor + atrazine at 2.2 + 2.2 kg·ha-1, did not reduce root length in one study, while the remaining atrazine and metolachlor + atrazine treatments reduced cumulative root length and total root biomass 20% to 60%. Metolachlor at 2.2 kg·ha-1 reduced St. Augustinegrass root biomass by >70% in one of two studies. St. Augustinegrass root elongation rate was linear or quadratic in response to all treatments. However, the rate of root elongation was similar to the untreated control for plants treated with isoxaben or oxadiazon. Chemical names used: 6-chloro-N-ethyl-N'-(l-methylethyl)-1,3,5-triazine-2,4-diamine(atrazine);S,S-dimethyl2-(difluoromethyl)-4-(2-methylpropyl)-6-(t∼fluoromethyl)-3,5-pyridinecarbothioate (dithiopyr); N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide (isoxaben); 2-chloro-N-(2-ethyl- 6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide (metolachlor); 3-[2,4-dichloro-5-(1-methylethoxy)phenyl]-5-(1,1-dimethylethyl)-1,3,4-oxadiazol-2-(3H)-one (oxadiazon); N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine (pendimethalin).

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Erick G. Begitschke, James D. McCurdy, Te-Ming Tseng, T. Casey Barickman, Barry R. Stewart, Christian M. Baldwin, Michael P. Richard and Maria Tomaso-Peterson

bermudagrass cover Hybrid bermudagrass plugs treated with indaziflam and liquid applied oxadiazon failed to reach 50% cover during the course of the experiment. Among the remaining herbicide treatments, all but atrazine and granular applied oxadiazon increased

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Nader Soltani, Peter H. Sikkema and Darren E. Robinson

There is little information published on the effect of residues from postemergence (POST) applications of foramsulfuron and preemergence (PRE) applications of isoxaflutole, and isoxaflutole plus atrazine in the year after application on vegetable crops. Three trials were established from 2000 to 2002 in Ontario to determine the effects of residues of foramsulfuron, isoxaflutole, and isoxaflutole plus atrazine on cabbage, processing pea, potato, sugar beet, and tomato 1 year after application. Aside from a reduction in sugar beet plant stand, there were no visual injury symptoms in any crop at 7, 14, and 28 days after emergence (DAE) in any of the herbicide carryover treatments. Isoxaflutole residues reduced shoot dry weight and yield as much as 27% and 28% in cabbage, and 57% and 60% in sugar beets, respectively. The addition of atrazine to isoxaflutole caused further reductions in shoot dry weight and yield of cabbage and sugar beet. Isoxaflutole plus atrazine residues reduced shoot dry weight and yield as much as 42% and 43% in cabbage, and 58% and 82% in sugar beets, respectively. There were no adverse effects on shoot dry weight and yield of processing pea, potato, and tomato from isoxaflutole or isoxaflutole plus atrazine residues in the year following application. Foramsulfuron residues at either rate did not reduce shoot dry weight or yield of any crops 1 year after application. Based on these results, it is recommended that cabbage and sugar beet not be grown in the year following the PRE application of isoxaflutole or isoxaflutole plus atrazine.

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Jayesh B. Samtani, John B. Masiunas and James E. Appleby

In some years, the emerging leaves of white oak and, to a lesser extent, of red oak in the Midwest have developed abnormally. This abnormality is referred to as leaf tatters. Reports to state foresters and Extension specialists associated tatters with herbicide applications. In 2005, white and red oak seedlings were treated in a spray chamber delivering 187 L/ha, with seven herbicides at three concentrations, 1/4×, 1/10×, and 1/100× of the standard field use rate. These herbicides and their standard field use rate of the active ingredients included atrazine at 2.3 kg/ha and chloroacetanilide herbicides: acetochlor at 2.0 kg/ha, metolachlor at 2.1 kg/ha, and dimethenamid at 0.8 kg/ha alone or mixed with atrazine at 2.3 kg/ha, at the leaves unfolding stage. After treatment, oaks were placed outdoors in a randomized complete-block design. Leaf symptoms in our study were similar to those seen in the landscape. In chloroacetanilide-treated white and red oak seedlings, browning of interveinal leaf tissues was noticed 5–6 days after treatment. The dried leaf tissues then dropped off, leaving only the main vein with little interveinal leaf area. In few seedlings treated with atrazine, the leaf tissues turned yellow to brown, while in few others, interveinal tissue damage was restricted, leaving small holes in the leaf. When chloroacetanilide herbicides were applied with atrazine, the dominant symptoms were those of leaf tatters. A few seedlings treated with dimethenamid and atrazine had predominately atrazine symptoms. Although new growth later in the season was not injured, the leaves with tatters remained on the plant until the end of the growing season. The study will be repeated in 2006.