Chemical Weed Control Methods Research Articles

Economic Comparison of Mechanical and Chemical Weed Control

The problem in determining the economic feasibility of mechanical, chemical, and combination weed control methods in corn (Zea mays L.) is a complex decision involving many factors. The effects of cost, yield, timeliness, and alternative uses of labor are the factors considered in comparing various methods of weed control in this study. Costs of weed control operations range from $2.84/A for two cultivations to $10.45/A for the most intensive, mechanical-chemical operation studied. Most common weed control methods have costs of approximately $3 to $4/A. Yields range from 83 bu/A for two cultivations to 96 bu/A with the highest cost chemical-mechanical weed control methods. All yields used in this study are supported by agronomic studies and are indexed on the basis of 100 bu/A for weed-free conditions. The consideration of both yields and costs does affect the selection of a weed control method. Considering only these two factors, mechanical methods have a slight advantage over chemical weed control methods. Penalizing mechanical methods because of delay or timeliness characteristics gives chemical methods an advantage by as much as $3.00/A. Alternative uses of labor, even though a common argument in selecting chemical or mechanical methods, is a very small item and has only moderate effects on the changes in net income.

Compatibility of Chemical and Mechanical Weed Control Methods

Herbicides were applied postplant to field grown peanuts (Arachis hypogaea L.) and cotton (Gossypium hirsatum L.) in association with various cultivation devices. Rotary cultivations were compatible with single or multiple chemical treatments applied to soil. For eight preemergence herbicides commonly used on a nonincorporated basis, use of the multiple-application multiple-rotarycultivation technique, in comparison to the common method of use, increased the early-season weed control rating from 3.4 to 4.5 (scale 1.0 = no control, 5.0 = perfect), reduced weeds from 209 to 37 plants/50 sq ft, increased length of control from 36 to 50 days, and reduced the manual hoe time requirement from 24 to 10 hr/A. Incorporation of single or multiple chemical treatments decreased crop safety for some herbicides especially where cotton was the crop. The power driven rotary cultivator was superior to the standard sweep-equipped cultivator and the weeder for use in conjunction with multiple chemical applications. Herbicidal applications incorporated with the rotary cultivator at 0, 7, and 14; 7, 14, and 21; or 0, 14, and 28 days after planting provided equal weed control.

Weed Control in Root Crops by Pre-sowing Applications of iso-Propylphenylcarbamate and Mixtures of that Substance and ‘Methoxone’ or 2,4-Dichlorophenoxyacetic Acid

PRELIMINARY trials during the past two years, which aimed at replacing costly cultivations in root crops by chemical methods of weed control, have now been completed at Jealott's Hill. iso-Propylphenylcarbamate, ‘Methoxone’ (2,methyl-4,chlorophenoxyacetic acid) and 2,4-dichlorophenoxyacetic acid were known to prevent the germination of certain plant species when applied as pre-emergence dressings1,2, and the species response to iso-propylphenylcarbamate was different from that of the other two compounds. Therefore, mixtures of iso-propylphenylcarbamate with ‘Methoxone’ and with 2,4-dichlorophenoxyacetic acid were examined alongside pre-emergence dressings of the individual components.