Completion Report: Arkansas State Pesticides in Ground Water Monitoring Project Phase V: Vulnerable areas in Jackson, Monroe, Lawrence and Lonoke Counties

In 1996, sixty-seven water samples were drawn from 65 wells, including 62 new wells and 3 wells sampled previously . One Woodruff County well and two Pulaski County wells were resampled. Thirty-two samples were drawn from 30 wells in Monroe County (well #1 was sampled 3 times during this phase) . Ten wells in Jackson County, 12 wells in Lawrence County and 10 wells in Lonoke were also tested (Figures 1-5) . With the completion of Phase V, the number of wells tested has risen to 231 with a total of 258 samples analyzed . Initially, the wells were tested for 13 pesticides and ni~rate. Two more pesticides, aldicarb and carbofuran were added to the analyte list during Phase V. The analyte list is shown in Table 3 . All results from all the wells are listed in Appendix A. Quality control information for these data follow the results. The Phase V Quality Assurance Report is included in this document as Part II

Field Evaluations of Herbicides on Vegetable, Small Fruit, and Ornamental Crops, 2000, 2001, & 2002

Field evaluations of herbicides provide the chemical industry, governmental agencies, such as IR-4, and the Arkansas Agricultural Experiment Station with an evaluation of herbicide performance on small fruit, vegetable, and ornamental crops grown under Arkansas conditions. This report provides a means for disseminating information to interested private and public service weed scientists

Ground Water Monitoring Project for Arkansas, Phase III

This report is composed of two parts. The first part is an interpretation of the pesticide and nitrate data collected in Woodruff County based on samples collected during 1994. Because there is an indication that there were hydrological differences between 1994 and 1995, and because most of the pesticide data is from 1994, this interpretive portion is restricted to 1994 data. Six wells initially sampled in 1994 that contained pesticides had continuing contamination in re-sampling in 1994 and 1995. Part II lists a seventh well in Woodruff County that contained pesticides in February and May of 199

Abundance of Cereal Aphids (Homoptera: Aphididae) and Their Predators in Spring Wheat-Alfalfa Intercrops Under Different Crop Management Intensities

Natural infestations of cereal aphids and abundance of their predators were compared from 1990 through 1993 among plots of intercropped spring wheat and alfalfa grown under high, intermediate, or low crop management intensity (CMI). CMI treatments differed in the amount of nitrogen fertilizer applied and herbicide used and in the rigor of tillage operations. Cereal aphids (primarily Rhopalosiphum padi, Sitobion avenae, and Schizaphis graminum) collectively infested a mean of 0 to 5.9 of 15 wheat tillers sam­pled per plot on various dates from 1990 through 1993, but aphid infestation did not vary by CM!. Seven taxa of aphid predators predominated: Nabis spp., Chrysoperla spp., Coleomegilla maculata, Hippodamia convergens, H. tredecimpunctata tibialis, H. parenthesis, and Coccinella septempunctata. Coccinella transversoguttata richardsoni, a species in decline in eastern South Dakota, was not collected. Nabids were generally the most abundant predatory taxon. In 1992, coccinellid adults were more abundant in high than low CMI plots. In 1993, H. tredecimpunctata tibialis adults were significantly more abundant in high CMI plots on the first three sampling dates but became more abundant in the low and intermediate CMI plots by the fifth sampling date. Regressions between the number of aphid-infested tillers and abundance of some predator taxa were significant in 1990, 1991, and 1992. In 1990, most regressions showed that counts of predators (except Chrysoperla spp. adults) were inversely proportional to aphid infestation levels, whereas significant regressions in 1991 and 1992 showed that the abundances of predators were weakly proportional to aphid infestation levels. Adjusted r2 values for all significant regressions ranged from 0.07 to 0.27. Relationships between crop management, cereal aphid infestation, and aphidophagous predators are discussed

Efficacy of herbicides on the control weeds and productivity of direct seeded rice under minimal water conditions

Field experiments have been conducted at the MARDI Seberang Perai Research Station for two seasons: main season 2005/2006 (October - February) and off-season 2006 (March - September) to determine the efficacy of herbicides in controlling weeds and their subsequent effect on rice productivity. Ten herbicides widely used and available in the market have been evaluated singly, as mixtures and as sequential applications in direct seeded rice fields during critical period of weed competition under minimal water conditions of less than 2 cm water depth. In main season the hierarchical position of the four dominant weed species out of 10 species were Fimbristylis milliaceae > Lndwigia hyssopifolia > Leptochloa chinensis > Echinochloa crus-galli, this was completely reverse to that of off-season where Echinochloa crus-galli > Leptochloa chinensis > Fimbristylis milliaceae > Limnocharis flava. Seven of the eighteen treatments over the two cropping seasons showed better broad spectrum weed control, increased grain yields and better yield component indicators. Due to variation of the dominant weed infestation between seasons the potential treatments were pretilachlor followed by bentazon/MCPA (T2), cyhalofop-butyl + bensulfuron followed by bentazon/ MCPA (T4), bispyribac-sodium followed by bentazon/MCPA (T6), benthiocarb/ propanil followed by bentazon/MCPA (T8), penoxsulam + benthiocarb followed by bentazon/MCPA (T10), fenoxaprop-p-ethyl/safener + benthiocarb/ propanil followed by bentazon/MCPA (T12) and quinclorac + benthiocarb/propanil followed by bentazon/MCPA (T14) in main season and Pretilachlor followed by bentazon/MCPA (T2), bispyribac-sodium followed by bentazon/MCPA (T6) and penoxsulam + benthiocarb followed by bentazon/MCPA (T10) in off-season. Rice yield losses due to weed competition in unweeded treatments were 60% in main season and 54% in off-season. This experiment showed that sequential herbicide applications at the critical period of weed competition would give a better result compared to a single herbicide application

Interactions of Mefluidide and Bentazon on Red Rice (Oryza Sativa L.).

The responses of soybeans {Glycine max (L.) Merr. \u27Bragg\u27} and red rice (Oryza sativa L. \u27Strawhulled\u27) to postemergence applications of mefluidide {N-{2,4-dimethyl-5-{{(trifluoromethyl)=sulfonyl}amino}phenyl}acetamide} and bentazon {3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide} alone and in combinations were evaluated in greenhouse studies. Soybeans and red rice were tolerant to bentazon, but their heights were reduced by mefluidide. When these two herbicides were combined, soybeans were not injured at any tested rates, but a synergistic interaction occurred that killed red rice. The changes in degradation, uptake, translocation, metabolism, and loss of these two herbicides due to combinations with each other were studied in order to establish the basis for synergistic interactions of this herbicide combination on red rice. The combinations of these herbicides resulted in decreased degradation and uptake of both herbicides and decreased loss of only mefluidide as compared to either used alone. The translocation of both herbicides was primarily acropetal with limited basipetal movement. The translocation of (\u2714)C from mefluidide from the treated-middle leaf was reduced by bentazon sprayed over-the-top, however, the entire plant showed necrosis. Mefluidide, sprayed over-the-top, increased the translocation of (\u2714)C from bentazon, but necrotic symptoms appeared only on the bentazon-treated middle leaf. There were no significant changes in the metabolism of mefluidide due to addition of bentazon. Mefluidide reduced the rate of metabolism and conjugation of bentazon by red rice, and consequently high levels of free bentazon were maintained within the plant. Application of mefluidide 32 h following that of bentazon also resulted in a synergistic response to red rice. Although all the bentazon absorbed by red rice prior to delayed application of mefluidide was conjugated within 32 h, the mefluidide treatment prevented further conjugation of bentazon which continued to enter the plant. The identified metabolites of these two herbicides in red rice were not toxic to the plant. The inhibition of bentazon detoxification by mefluidide in red rice appears to result in the apparent synergistic interactions between the herbicides. Free bentazon remaining in the plant probably caused necrosis and death of red rice

Field Evaluation of Herbicides on Vegetables and Small Fruits 2004

Herbicide evaluation studies on vegetables and small fruits were conducted in 2004 at the Arkansas Agricultural Experiment Station at Fayetteville, AR, in an effort to evaluate new herbicides, herbicide mixtures, and their application timings for weed control efficacy and crop tolerance. Results of these studies, in part, provide useful information to producers, fellow researchers, the Crop Protection Industry, and the IR-4 Minor Crop Pest Management Program in the development of potential new herbicide uses in vegetable, and fruit

ECONOMIC AND ENVIRONMENTAL EFFECTS ASSOCIATED WITH REDUCING THE USE OF ATRAZINE: AN EXAMPLE OF CROSS-DISCIPLINARY RESEARCH

Restricting or eliminating the use of atrazine in the Midwest would have important economic consequences for farmers, consumers, and the environment. These consequences can only be evaluated with cooperation between economists and weed scientists. The weed control choice set available to farmers cannot be observed through deductive research. Economists and weed scientists worked together to identify all possible weed control strategies for corn and sorghum in the Midwest and to incorporate them into an economic model. An atrazine ban was found to be the costliest strategy, and a targeted, water-quality based strategy the most cost effective.Atrazine, Deductive research, Environmental exposure, Herbicides, Inductive research, Welfare, Crop Production/Industries,