Herbicide Evaluation in Arkansas Cotton, 1999

Herbicidal weed control is economically important for production of cotton. Field experiments are conducted annually in Arkansas to evaluate the activity of developmental and commercial herbicides for selective control of weeds in cotton. These experiments serve both industry and Arkansas agriculture by providing information on the selectivity of herbicides still in the developmental stage and by comparing the activity of these new herbicides with that of recommended herbicides

Field Evaluation of Herbicides on Small Fruit, Vegetable, and Ornamental Crops, 1997

Growers generally use herbicides to efficiently produce high-quality fruit and vegetables for processing or fresh market sales. Due to the smaller acreage of these crops compared to major field crops, fewer herbicides are registered for use in fruit and vegetable crops than for field crops. Each year, new herbicides are evaluated under Arkansas growing conditions with the objective of improving the herbicide technology for the grower, processor, and ultimately the consumer. This report includes studies on the control of many of the more serious weed problems in important crops of this region, including snapbeans, spinach, southern pea, watermelon, cantaloupe, tomato, blackberry, and grape. In addition, the report includes information on the tolerance of selected bedding plants to some effective herbicides

An Evaluation of Herbicides for Control of Wild Oats in Barley: Efficacy, Phytotoxicity, and Barley Variety Susceptibility Studies

The control of wild oats (Avena Jatua L.) in Alaskan spring-planted barley was investigated in a series of experiments conducted from 1981-1984. Rates and times of applications of triallate (a preemergence, soil-incorporated herbicide), diclofop, barban, and difenzoquat (postemergence herbicides) were investigated in relation to control of wild oats and barley yield in 1981-1982. Because of very high wild oats populations. none of the herbicides controlled wild oats to the point of· allowing a barley harvest. Generally, wild oats were best controlled when herbicides were applied at an early growth stage and at the highest application rates. Control of wild oats with triallate was the same whether incorporated using parallel or perpendicular passes of a spike-tooth harrow. In 1983-84 both single herbicide treatments and combinations of herbicides were studied. Barban, diclofop, and difenzoquat were applied alone or with triallate applied in the fall or spring in emulsifiable concentrate or granular formulation. Wild oats population levels were lower in these 2 years, and applications of even single herbicides provided good wild oats control. Of the individual herbicides, diclofop provided the best control of wild oats. In general, when triallate was applied in conjunction with diclofop, barban, or difenzoquat, control of wild oats was better and higher barley yields were obtained than when a single wild oats herbicide was applied. When triallate was applied in the fall, the granular formulation provided better control of wild oats than the emulsifiable formulation. In a study of the response of eight barley varieties ('Eero', 'Paavo', 'Galt', 'Otra', 'Otal', 'Datal', 'Udal', 'Weal') to high rates and late times of application of the four herbicides, none of the varieties were differentially susceptible. Diclofop decreased heights of all varieties and decreased test weights

Effects on herbicides on hedgerow biodiversity

Low dosages of herbicides may reduce the number of flowers on non-target plants. Effect of herbicides on flowering and on pollen and nectar production are relevant end-points for effect assessment on non-target species. Herbicides have the potential to reduce the number of flowers in hedgerow vegetation and thereby also decrease the availability of pollen, nectar and seeds that are important food for many insects and birds. The biodiversity of hedgerow bottom vegetation is lower at conventional than at organic farms, presumably as a consequence of the herbicide use

Weed problems and possibilities for their control in salix for biomass

Salix is a dedicated arable bioenergy crop that is presently grown on 12,000 ha in Sweden. It has probably the best environmental profile among the arable bioenergy crops grown in Sweden partly because neither fungicides nor insecticides are used in the production. However, herbicides are used routinely, because salix plants are very sensitive, especially during the first growing season, to competition from weeds. Hence, to improve the environmental profile of salix even further, alternative weed control methods that complement or for substitute the use of herbicides are desired. Some of these alternatives might be to improve the mechanical weeding techniques, using cover crops, applying herbicides more accurately or to breed for weed competitiveness. The purpose of this introductory paper is therefore to review what is known about weeds in relation to biomass salix. To put this subject into context there will first be a general overview of salix and the current production system

Herbicide-Resistant Soybeans in Arkansas: Lessons Learned and Future Direction

In Arkansas Delta soybean production, glyphosate resistant (GR) Palmer amaranth has significantly impacted weed management. The incidence of herbicide resistant (HR) weeds has farreaching crop science, economic, and communications implications, which have been explored by the corresponding expertise of our research team members to form a comprehensive literature review. The review was used to develop policy recommendations to address current and future HR genetically modified (GM) crop use and the associated issues. The review of crop science research indicated an overall increase in herbicide application, as well as an increase in weed management programs focused around glyphosate rather than the application of multiple herbicides. The review also revealed some management methods have potential to resolve the problem, including alternating herbicide application, avoiding sub-lethal rates, using “burn down” herbicides prior to planting, crop rotation, tillage, and zero tolerance weed policies. The use of fewer herbicides rather than multiple types creates a monopolistic edge for the companies producing those few herbicides, allowing greater market control. Crisis communication methods, including developing internal readiness, conducting needs assessments, developing a relevant message, and conveying the message through appropriate channels, can be used to develop a response to the issue that will best communicate necessary information to the target audience. The team used these findings to formulate policy recommendations, which include management, economic, and communication plans that may provide a starting point to address the issue

Measurements of Penetration and Detoxification of PS II Herbicides in Whole Leaves by a Fluorometric Method

The effect of herbicides that inhibit the photosynthetic electron transport at the photosystem II acceptor side has been analyzed in whole plants by using a fluorometric method. The data reported indicate that the apparent variable fluorescence of the induction curve normalized to the control value provides reliable information about the penetration rate and metabolic detoxification of PS II herbicides in whole plants

Herbicide mixtures at high doses slow the evolution of resistance in experimentally evolving populations of Chlamydomonas reinhardtii

The widespread evolution of resistance to herbicides is a pressing issue in global agriculture. Evolutionary principles and practices are key to the management of this threat to global food security. The application of mixtures of herbicides has been advocated as an anti-resistance strategy, without substantial empirical support for its validation. We evolved experimentally populations of the unicellular green chlorophyte, Chlamydomonas reinhardtii, to minimum inhibitory concentrations (MICs) of single-herbicide modes of action and to pair-wise and three-way mixtures between different herbicides at various total combined doses. Herbicide mixtures were most effective when each component was applied at or close to its MIC. When doses were high, increasing the number of mixture components was also effective in reducing the evolution of resistance. Employing mixtures at low combined doses did not retard resistance evolution, even accelerating the evolution of resistance to some components. At low doses, increasing the number of herbicides in the mixture tended to select for more generalist resistance (cross-resistance). Our results reinforce findings from the antibiotic resistance literature and confirm that herbicide mixtures can be very effective for resistance management, but that mixtures should only be employed where the economic and environmental context permits the applications of high combined doses

Absence of effects of herbicides use on yam rots : a case study in Wulensi, Ghana

Yam farmers in Ghana have, over the years, used herbicides for weed control, particularly glyphosate. Although this has been helpful to them, there are complaints and concerns, among the yam farmers and a section of the public, that the yam tuber rots easily under the use of herbicides. This study, therefore, was set up at the field level to investigate the possibility of herbicides use causing yam rot. Two yam varieties, laribako and olodo, were grown under the conditions of chemical weed control (use of glyphosate) and manual weed control in three replicate sites in Wulensi in the Nanumba traditional area of northern Ghana. The study revealed that there was no difference in rots between herbicide treated yams and manually weeded yams, but that there was a difference in rots between laribako and olodo yam varieties. The results also showed that there was no difference in yield between herbicide treated yams and manually weeded yams. Based on the findings, it can be concluded that, there was no difference in yam rot and yield between herbicides treated and manually weeded yams, but laribako was more susceptible to rot than olodo