Roadside weed control research in Oklahoma is concerned both with selective and nonselective herbicides for the control of undesirable grasses and broad-leaved weeds. The evaluation of herbicides for the most effective and economical means of weed control on the highway system is the objective of this research program. These research results, even though involved with a common purpose, are presented as 3 separate studies for clarity and convenience. The post-emergence herbicides such as ama (ammonium methanearsonate), cma (calcium acid methyl arsonate), dsma (disodium methanearsonate), and msma (monosodium acid methanearsonate), each with one retreatment 7 to 20 days after the initial application, are equally effective in the control of sandburs. Based on the cost per acre, dsma is the least expensive. The pre-emergence application of atrazine is the most effective herbicide for the control of both broad-leaved weeds and annual grasses commonly found on Oklahoma highways. For only broad-leaved weeds the herbicides 2,4-d amine, 2,4,5-t amine, and dicamba (banvel-d) are recommended; based on cost per acre, 2,4-d generally is the least expensive. The most effective herbicides for the control of alfalfa (medicago sativa) and sweet clover (melilotus officinalis) are 2,4-d amine, 2,4,5-t amine, and dicamba (banvel-d); 2,4-d generally is the least expensive. The organic arsonate herbicides, dsma and msma, are the most effective materials evaluated for the selective control of johnson grass. Based on cost per acre, dsma is the least expensive. The herbicides recommended for the suppression of all plant growth, especially bermuda grass on shoulders, under guardrails, and around signposts, are bromacil, borocil, tca inhibited, borea t-10, and a combination of tca and bromacil. Based on the cost per foot-mile, tca inhibited is the least expensive. /author/
Samenvatting