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Megh Singh, Shiv D. Sharma, Analiza H.M. Ramirez and Amit J. Jhala

leaves) johnsongrass. Percent control was estimated visually at 14 d after treatment (DAT) based on a scale of 0% to 100%, where 0% indicates no damage and 100% indicates complete plant death ( Frans et al., 1986 ). Aboveground biomass from each pot was

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Megh Singh, Mayank Malik, Analiza H.M. Ramirez and Amit J. Jhala

/100 L solution and crop oil concentrate at 1% v/v. Visual percent control of grass and broadleaf weeds was recorded at 7, 15, 30, 60, and 90 DAT on a scale 0% to 100%, where 0% being no control and 100% being complete control of all weeds at the time

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Amit J. Jhala, Analiza H.M. Ramirez and Megh Singh

/acre spray volume at 30 psi. Citrus species was sweet orange ( Citrus sinensis ) ‘Valencia’ and ‘Navel’ at Winter Garden and Haines City, respectively. The citrus trees were two years old at the time of the herbicide spray. Visual percent control of grass and

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

Potato (Solanum tuberosum) is one of four major food crops in the world. Weed control is a major component in potato production and has been accomplished using different methods, including but not limited to the use of herbicides and straw mulch. A combination of preemergence herbicide and straw mulch may improve weed control; however, no information is available for combining both methods, along with their effects on weed control, weed density, and potato tuber yields. The objective of this study was to evaluate weed control in potato using atrazine or straw mulch applied alone at different rates or in combination. A field experiment was conducted for 4 years from 2006 to 2010 in Ludhiana, Punjab, India. Common weeds included burclover (Medicago arabica), common lambsquarters (Chenopodium album), littleseed canarygrass (Phalaris minor), purple nutsedge (Cyperus rotundus), scarlet pimpernel (Anagallis arvensis), swinecress (Coronopus didymus), and toothed dock (Rumex dentatus). Results suggested that atrazine applied alone was not very effective and resulted in 0% to 78% control depending on the weed species being investigated at 30 days after treatment (DAT). Straw mulch applied alone at any rate provided ≥90% control of toothed dock, but control of other weed species was variable. A combination of atrazine and straw mulch at any rate usually resulted in >90% weed control at 30 DAT, except for swinecress and purple nutsedge. This treatment combination also resulted in weed density as low as 0 plant/m2 for common lambsquarters, scarlet pimpernel, and toothed dock. Potato tuber weight and yield was significantly higher in all treatments compared with untreated control without difference among them. It is concluded that a combination of straw mulch and atrazine can provide effective weed control in potato.

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S.D. Sharma and M. Singh

observations of phytotoxic effects were recorded as percent control of weeds using a 4-week period after treatment (WAT). The rating scale was 0 to 100, with 0 implying no control and 100 implying complete control of the weed plants, as approved by the Weed

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Wheeler G. Foshee III, Collin W. Adcock, Glenn R. Wehtje, Charles H. Gilliam and Larry W. Wells

Effects of combining labeled rates of halosulfuron (Sandea) and s-metolachlor (Dual Magnum) were evaluated as a preemergence (PRE) application in a randomized complete block designed experiment at the Wiregrass Experiment Station in southeastern Alabama. Treatments were assigned in a factorial arrangement of four levels of halosulfuron (0.0, 0.009, 0.018, and 0.036 lbs. a.i./acre) and six levels of s-metolachlor (0.0, 0.25, 0.50, 0.75, 1.0, and 1.25 lbs. a.i/acre). The purpose of the study was to ascertain possible synergistic effects from combining these two herbicides to control nutsedge at a possible lower cost. Two repetitions were completed in 2005 with data pooled in analysis. Results found no interaction between the halosulfuron and the s-metolachlor and therefore no synergistic affects. Analysis of the main effects revealed that the highest labeled rate of either herbicide gave the highest percent control relative to the nontreated control. Soil activity of halosulfuron in controlling nutsedge has been shown to be less effective than foliar applications. Our own LD90 greenhouse studies confirmed this to be true. We examined four application techniques of halosulfuron (POST both soil and foliar, POST foliar only, POST soil only, and PRE soil only) to determine the LD90. Results revealed that halosulfuron had the lowest LD90 from the treatments with a foliar application. However, some soil activity was observed. Results from field studies indicated that PRE applications of halosulfuron must be at the highest labeled rate to provide effective control. S-metolachlor was equal to halosulfuron on percent control and is lower in cost on a per acre basis.

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Debalina Saha, S. Christopher Marble, Brian J. Pearson, Héctor E. Pérez, Gregory E. MacDonald and Dennis C. Odero

in nontreated pots (no mulch and no herbicide) and pots receiving either a herbicide or a mulch treatment were used to calculate percent control and the percent increase in control achieved with the herbicide + mulch combination compared with either

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Zane Raudenbush and Steven J. Keeley

less injury were considered to be alive. Percent control was calculated by comparing the counts of alive dandelions in treated plots with the mean count of the six untreated plots in the same replication, e.g., [(mean count of untreated plots – count of

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Joshua J. Skelton, William Sharp and Bruce E. Branham

complete necrosis. In the Oct. 2010 trial, data were also collected weekly for KBG visual injury on a 0% to 100% scale because the KBG cover was much higher than the other trials. Percent control was calculated from initial and final visual estimates of ABG

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Rebecca M. Koepke-Hill, Gregory R. Armel, William E. Klingeman, Mark A. Halcomb, Jose J. Vargas and Phillip C. Flanagan

the growth of a perennial weed like mugwort ( Robinson et al., 2003 ; Senseman, 2007 ). Percent control ratings were taken at 56 and 365 d after treatment, whereby 0 indicated no control and 100 indicated complete control. Stand counts of mugwort were