In recent years, chemical control methods have been discovered for most common annual weeds with the notable exception of wild oats. Isopropyl N-phenyl carbamate (IPC) and isopropyl N-(3–chlorophenyl)-carbamate (CIPC) appeared promising in 1950 when they successfully controlled wild oats in barley at University Farm, Saint Paul, Minnesota. In the spring of 1951, investigations were started in an attempt to evaluate these two chemicals further for selective use in field crops.

Peas grown for canning purposes are subject to infestations of weeds even though recommended cropping practices are followed. If weeds are numerous they cause reduced yields of shelled peas and variable maturity. The quality of the pack of peas may also be affected for floral buds and fragments of the weeds are difficult to separate from the shelled peas. Excessive costs for seed peas may result from using high seeding rates in an attempt to control weeds by increasing the competitive ability of the peas.

The basis for a sound weed control program is the ability of the majority of the people to identify weed plants and seeds. Too often a patch of weeds becomes a menace to the community before the seriousness of it is realized. Lack of interest in identification led to the investigation of methods, aids and techniques that could be employed to reach and teach people, both adults and youth, to identify weed plants and seeds. The approach was through weed plant identification mounts, weed seed identification boards and through the use of slides. Also utilized were tours, field trips, botany schools, etc. Emphasis will be placed on aids that have been constructed for general use for indoor meetings. It should be stressed at the outset that there is no best way, one needs to utilize every method at his command.

A seed field of bolting onions is extremely difficult, if not impossible, to weed satisfactorily by hoeing or any mechanical means without serious reduction in seed yield, because of the ease with which seed stalks are broken. Injury to seed stalks results in lower seed yields, but if the weeds are allowed to grow they also reduce seed yields. The presence of weed seeds makes cleaning more difficult and may reduce yields further, because foreign material and weed seeds can rarely, if ever, be separated satisfactorily without the removal of some crop seed. Actually few, if any, commercial growers practice either cultivation or handweeding after the onion crop has begun to go to seed. Consequently, exceptionally weedy fields are common in onion-seed-growing sections. The use of herbicides as a possible solution to this difficult problem has been studied in Utah since 1949, with some promising results.

Promising results of applications of α, α-dichloropropionic acid (Dalapon) to wild oats (Avena fatua) were first reported in May 1953 in Dow Chemical Company's Dalapon Bulletin No. 1. Encouraging results with Dalapon on wild oats were obtained by various workers during the summer of 1953. The work reported herein was conducted in 1954 to gain further information on the effects of Dalapon on wild oats.

Numerous investigations in which crop plants were utilized to study the effect, persistence, and movement of spray residues of 2,4–dichlorophenoxyacetic acid (2, 4–D) in a variety of soils and under a wide range of conditions have been reported. However, except for a report by Arle (1), a search of the literature has revealed no direct information on the effects of 2,4–D when applied in irrigation water to crop plants growing in the field. Arle treated cotton with irrigation water containing 2,4–D in equivalents ranging from 0.5 to 8 pounds per acre. Significant decreases in yield usually resulted from the higher rates of treatment when applications were made early in the season. Applications at the lower rates usually resulted in yields about equal to or greater than those obtained from check plots.

Crabgrass, the universal lawn weed, has been the object of much research in the past few years. Lawn owners, cotton and vegetable growers, and golf course keepers have long been fighting this pest. Today, chemical eradication is rapidly displacing costly, difficult, and often ineffective mechanical control methods.

Shortly after we had completed several studies of the effect of the new herbicide, dalapon, (2,2–dichloropropionic acid), on enzyme systems, it became apparent that high concentrations of this compound inhibited a variety of different enzymes in a noncompetitive fashion. Furthermore, transparent solutions of enzymes frequently became quite turbid when this inhibitor was added. Such behavior suggested that 2,2–dichloropropionic acid was acting as a protein precipitant.