Successful Weed Control Research Articles

Alternative Tillage and Herbicide Options for Successful Weed Control in Vegetables

Increased federal and state regulations resulting from concerns for pesticide-free food and protection of ground water have created the need to reevaluate weed control strategies that currently depend on chemicals (Sweet et al., 1990). Cultivation and hand-weeding are feasible for small-scale growers but are usually not economical for large, commercial growers. Weed control in vegetables relies heavily on soil-applied, preemergence herbicides. However, with the development of selective, postemergence herbicides that can be applied as needed, growers may now fine-tune weed control strategies, combining the new herbicides with reduced rates of soil-applied herbicides and cultivation. Reducing inputs and integrating farming practices to lower costs and reduce environmental impacts while maintaining successful weed control is difficult (Edwards and Regnier, 1989). However, strategies that may reduce chemical inputs include: delaying applications of reduced rates of preemergence herbicides, banding herbicides over the crop row, using mulch and reduced tillage systems that aid in weed suppression, tank-mixing low rates of postand preemergence herbicides, applying postemergence herbicides after cultivation, and using new, environmentally “soft” herbicides that are active at extremely low doses. The objective of this paper is to discuss previous and current research that integrates tillage, mulches, and low-rate applications of herbicides for use in commercial vegetable production.

The effect of the annual use of pesticides on soil microorganisms, pesticide residues in the soil and barley yields

AbstractA study has been made of the influence of pesticides used annually on soil microorganisms and crop yields. The persistence of these pesticides in the soil was also investigated. The herbicides MCPA, glyphosate, maleic hydrazide and tri‐allate, and the insecticide parathion, were applied on experimental plots on which barley was grown during the years 1973‐1981. The fungicide 2‐methoxyethylmercury chloride was used every year for dressing the seeds grown in pesticide‐treated plots. The pesticide treatments did not affect significantly the numbers of several groups of soil microorganisms. A slight increase was, however, observed in the nitrification activity in the soil. The barley yields were on average higher on pesticide‐treated plots than on controls because of successful weed control. Pesticide residues in the soil were generally very low; for example, for parathion they were below 0.02 mg kg−1 within 11 days, and for MCPA 0.06 mg kg−1 within 7 days. However, the glyphosate residue was 1.6 mg kg−1 in the autumn 2 days after the treatment, and the residue settled to a level of 0.2 mg kg−1 during the following summer. No clear dependence was observed between the residue level and the time between treatment and sampling.

THE DEVELOPMENT OF HERBICIDES FOR POTATOES

Summary. Since 1961 the Weed Research Organization has been testing and developing herbicides for weed control in potatoes. Inthe three experiments which are reported, herbicides were compared with other forms of weed control. The first experimentin 1961 was exploratory and compared yields following hand‐weeding versus no weed control versus several promising herbicides. The highest yield was produced by the hand‐weeded crop. Several herbicide treatments applied before crop emergence gave useful selective weed control.Assuming weed control to be necessary, selected herbicides were then compared in 1962 and 1963 with conventional mechanical cultivations. In both years successful weed control by herbicide resulted in a higher yield of potatoes than did mechanical cultivation although the soil‐acting chemical used in 1962 caused some crop damage. The 1963 experiment included triangular planting patterns, at normal and high plant densities. Increases both in gross and marketable yield were obtained at normal plant density with the triangular arrangement as compared with the row crop. The high plant population resulted in the largest gross yield but a lower yield per plant and smaller average tuber size.