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

-metolachlor, and acetochlor are the most common herbicides applied to corn in the midwest ( U.S. Department of Agriculture, 2006 ). In Illinois, misapplications of dicamba or 2,4-D (growth regulators) are the most common cause of drift injury complaints ( Mohr

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John W. Wilcut, Charles H. Gilliam, Glenn R. Wehtje, T. Vint Hicks, and Diane L. Berchielli

Preplant-incorporated, preemergence, and postemergence herbicides were evaluated for yellow nutsedge (Cyperus esculentus L.) control and for phytotoxicity to four container-grown woody plants. Preplant-incorporated or preemergence applications of chlorimuron at 0.07 kg a.i./ha or imazaquin at 1.12 kg a.i./ha provided the greatest control of yellow nutsedge. Imazaquin applied at 0.28, 0.56, 0.84, or 1.12 kg a.i./ha suppressed growth of Rhododendron × `Copperman' azalea and Lagerstroemia indica ×sfauriai `Natchez'. All other herbicides tested were safe on the four woody plants evaluated. Chlorimuron provided the best combination of yellow nutsedge control and tolerance on woody ornamental. Chemical names used: 2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino]carbonyl]amino]sulfonyl]benzoic acid (chlorimuron); 2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid (imazaquin).

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

In 2004 and 2005, potted white oak seedlings 0.6 m in height were treated with six herbicide treatments 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 active ingredient (a.i.) included 2,4-D at 1.5 kg/ha, 2,4-D + glyphosate at 0.8 kg/ha + 1 kg/ha, acetochlor + atrazine at 3.5 kg/ha, dicamba at 0.7 kg/ha, glyphosate at 1.1 kg/ha and metolachlor at 2.0 kg/ha. The seedlings were treated at three growth stages: swollen buds, leaves unfolding, and expanded leaves. A compressed air spraying chamber delivering 187 L/ha was used to apply the herbicides. After treatment, the containers were placed in an open field plot in a completely randomized design. Oak seedlings were most susceptible to herbicide injury at all concentrations, at the leaves unfolding stage. Symptoms on seedlings treated with 2,4-D and dicamba at the leaves unfolding stage included leaf cupping and rolling, leaf curling, leaf rolling downward from leaf margin, and unusual elongation at leaf tip. Glyphosate + 2,4-D applications resulted in leaf cupping, yellowing, leaf rolling downward from leaf margin and abnormal leaf tips. Glyphosate symptoms ranged from leaf yellowing and browning, to slight browning of interveinal leaf tissues. Acetochlor + atrazine, or metolachlor alone caused the abnormality referred to as “leaf tatters” where in severe cases, only the main veins are present with limited amounts of interveinal tissues. Detailed description of the injury symptoms, supplemented with photographs are posted on a web site: http://www.nres.uiuc.edu/research/herbicide_research/index.htm

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Hannah M. Mathers and Luke T. Case

Two experiments were conducted at the The Ohio State University Waterman Farm, Columbus, on efficacy and phytotoxicity with evalautions at 30, 60, 90, and 120 DAT using dry weights and visual ratings 0–10 with >7 being commercially acceptable for efficacy, and 1–10 with <3 being commercially acceptable for phytotoxicity. The herbicide-treated mulches and herbicide–mulch application methods were compared to sprays of the five chemicals applied directly to the surfaces of the plots [oryzalin (oryzalin), (AS) Surflan (aqueous solution) 2 lb/acre (a.i.), flumioxazin (SureGuard WDG), 0.34 lb/acre (a.i.), acetochlor 76% (Harness 2.5 lb/acre (a.i.), dichlobenil (Casoron CS) 4 lb/acre (a.i.) and a combination of oryzalin and flumioxazin], two untreated mulches (pine and hardwood) and a weedy. Mulches were applied untreated, over the top of soil surfaces sprayed with the different herbicides. Mulches were also applied untreated to untreated soil surfaces and then sprayed with the different herbicides. Pretreated bark mulches were also evaluated and prepared by placing the mulches on a sheet of plastic, as a single layer thick and sprayed and allowed to dry for 48 hours. Twenty of 38 treatments gave efficacy rating of >7, pooled over all evaluation dates. One was a direct spray, Surflan + SureGuard (7.6). Three were pretreated mulches, Surflan + SureGuard (8.2), Harness (7.8) and Surflan (7.4) treated pine. None of the pretreated hardwood barks provided ratings of >7. Nine were treatments with the herbicides applied under the bark. Seven of the nine provided ratings of >8 and only one involved hardwood bark, Surflan + SureGuard under pine (9.1), Casoron under pine (8.9), Surflan under pine (8.7), Harness under pine (8.3), Harness under pine (8.0) and SureGuard under hardwood (8.0).

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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.

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Richard G. Greenland

Few herbicides are available for weed control in carrot. Many of those that are available are old and are in danger of being discontinued. From 2000–04, field experiments were conducted on sandy loam soils at the Oakes Irrigation Research Site in North Dakota to evaluate some of the newer herbicides for possible use in carrot production. Herbicides were tested with preplant incorporated (PPI), preemergence (PRE), and/or several postemergence (POST) application timings. The major weed in this study was hairy nightshade. Cloransulam applied PRE severely injured carrot. Dimethenamid reduced carrot stand and isoxaflutole injured carrots when they were applied PRE. Neither controlled hairy nightshade when applied either PRE or POST, resulting in carrot yield reductions. Acetochlor reduced carrot stand when applied PRE and did not control hairy nightshade when applied either PPI or PRE, resulting in reduced carrot yield. Mesotrione killed carrots when it was applied PRE, but only slightly injured carrots when applied POST. Carrot yield was reduced in some years due to lack of hairy nightshade control when mesotrione was applied POST. Sulfentrazone reduced carrot stand and yield when applied PRE. It was less injurious to carrots when applied POST, but carrot yields were reduced in some years due to lack of hairy nightshade control. Flumioxazin severely reduced carrot stand when applied PRE. When it was applied after carrots were 8 cm tall, it slightly injured carrots, but did not reduce yield except in one year when it did not control hairy nightshade. None of the herbicides tested did consistently as well as the old standards of linuron, DCPA, and trifluralin, but flumoixazin, sulfentrazone, and mesotrione may hold some promise if applied POST.

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

acetanilide herbicides such as S -metolachlor, acetochlor, and alachlor. However, pyroxasulfone provides superior control of certain important broadleaf weeds such as common ragweed and velvetleaf when compared with other acetanilide herbicides ( Dyer et al

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J. Scott McElroy, James D. McCurdy, and Michael L. Flessner

) Weed Sci. 53 202 211 Armel, G.R. Wilson, H.P. Richardson, R. Hines, T.E. 2003 Mesotrione, acetochlor, and atrazine for weed management in corn ( Zea mays ) Weed Technol. 17 284 290 Baird, J.H. Wilcut, J.W. Wehtje, G.R. Dickens, R. Sharpe, S. 1989

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Hela Chikh-Rouhou, Rafael González-Torres, José María Alvarez, and Ali Oumouloud

correlation studies in muskmelon Indian J. Agr. Sci. 49 361 363 Cohen, R. Blaier, B. Schaffer, A.A. Katan, J. 1996 Effect of acetochlor treatment on fusarium wilt and sugar content in melon seedlings