The control of annual weeds in row-planted crops such as soybeans and corn may become a major production problem whenever weather conditions limit the scope and effectiveness of tillage operations. With corn, the use of 2,4–D has greatly minimized this problem, but with soybeans the utilization of herbicides has been limited. Adaptation of herbicides to soybean production depends not only on herbicide performance but also on economic aspects of the problem. Recent studies (6, 7) reported average bean yield reductions of approximately 10 percent from the competition of average annual weed infestations. This emphasizes the importance of effective weed control and indicates some economic limits to the choice of methods to be utilized in practical weed control for soybeans.

A review of literature indicates that there are considerable variations in the results obtained in using herbicides for selective pre-emergence weed control. These variable results have been attributed in part at least to a large number of possible factors, a few of which are: soil type, soil moisture, soil surface condition, rainfall, plant varietal difference, and application variations and errors. In 1952 a study of the literature reporting research studies and recommendations indicated that some method of rolling or smoothing prior to pre-emergence applications might prove to eliminate those variations in results from such applications as could be attributed to the rough, cloddy condition of the soil surface. This was particularly noticeable in early bulletins of the cotton producing states, a number of which (1, 3, 4, 6, and 7) recommended that the soil surface be rolled smooth prior to the application of pre-emergence herbicides for weed control in cotton.

The mesquite problem on southern Arizona ranges has been comprehensively described by Parker and Martin (9), and certain ecological relationships of this noxious tree, insofar as are known, have recently been considered by Glendening and Paulsen (5). Although a serious problem only in the states of Arizona, New Mexico, and Texas, at least one of the three common varieties of Prosopis juliflora now may be found in each of eight southwestern states (2). Its progressive invasion is unquestioned.

In many areas of the southwestern states where cotton is a major crop, the use of 2,4–dichlorophenoxyacetic acid (2,4–D) is hazardous. Its use is restricted by law in many localities during the growing season. In these areas many perennial broad-leaved weeds which are susceptible to 2,4–D, at least to some degree, grow in abundance. Because of extreme arid conditions and other factors these weeds have not responded favorably to soil sterilants. There is urgent need for more effective herbicides for these weeds.

Establishment of new seedings of alfalfa is often difficult because of the many hazards encountered during the first season of growth. In the Central Great Plains moisture is often the major factor determining the degree of success of the operation. This condition can be accentuated by the presence of a population of annual grasses such as the foxtails (Setaria spp.) and barnyard grass (Echinochloa crusgalli L. Beauv.). These grasses have a more rapid seedling growth rate than alfalfa and tend to produce a drouthy condition in the soil by rapid utilization of the available moisture. The same effect often results from the use of oats or other small grains as companion crops.

Although many studies have been made on the behavior of herbicides in soils, there is still insufficient information to make intelligent use of many herbicides. Certain theories on herbicidal behavior in soils are well established in some regions, but the applicability of such theories to other regions under different soil and environmental conditions is not always known.

Perennial weeds capable of vegetative reproduction comprise, as a group, some of our most serious weed problems. Eradication is difficult where new top growth can be produced repeatedly from underground buds. A time honored control method involves the cutting of all top growth with special tillage implements each time sufficient new growth has been produced. In this way food reserves in the root system of the weed are slowly depleted until all growth stops. Root systems of most creeping perennial weeds are supplied with numerous buds on either the crown, lateral roots or rhizomes. Removal of the top growth of such plants with either chemicals or tillage results in the activation of a small percentage of the available buds and new top growth is produced. The new growth thus produced tends to prevent further bud activation presumably through the maintenance of auxin levels unfavorable for growth of these buds. This phenomenon is often referred to as apical dominance. Food depletion of the root system would be faster if more buds could be stimulated to active growth prior to each cycle of top growth removal.

The absorption and translocation of radioactive 2,4–D in bean plants has been studied by many workers (2, 4, 5, 7). The translocation of radioactive carbon from applied 2,4–D has been demonstrated to be more rapid in susceptible bean plants than in resistant plants such as corn and wheat seedlings (2, 3, 4). The difference in reaction of 2,4–D with plant constituents was further established between these two types of plants (3, 6). A compound designated as “unknown 1” was the major metabolic product formed in 2,4–D treated bean plants while “unknown 3” was found mainly in 2,4–D treated corn and wheat seedlings.

Field studies have been conducted at the Irrigation Experiment Station, Prosser, Washington, to determine the effects of 2,4–dichlorophenoxyacetic acid (2,4–D) in irrigation water on certain crop plants. The possibilities of contaminating irrigation water through the use of 2,4–D for weed control, particularly on ditchbanks, prompted these investigations. The response of Red Mexican beans and sugar beets to 2,4–D in irrgation water has been reported (1, 2). This publication deals with Concord grapes, a woody-type of crop plant.

It has been difficult to accept as conclusive the indications that butyl ester forms of 2,4–D are more effective in the control of big sagebrush (Artemisia tridentata) than are isopropyl ester forms (2, 3, 5). Such indications may have been due to the manner of formulating the materials, and to the additives contained, rather than to differences between the esters. Additional information is necessary to prevent bias in the choice among ester forms.

Probably no range weed has received such immediate and widespread attention as halogeton (Halogeton glomeratus (M. Bieb.) C. A. Mey.) following the large losses of sheep caused by this plant in 1949. Halogeton was first identified in the United States from a specimen collected south of Wells, Nevada, in 1934 (5). Its poisonous properties were discovered in 1942 (7). The time and method of its introduction into the United States are unknown. It is known to be a native of the arid and semiarid plateau regions east of the Caspian Sea and to extend into northwestern China and southwestern Siberia and southward as far as the highlands of Afghanistan and northwestern India.

The gross annual wholesale value of Easter lilies and other ornamental bulb crops grown in the United States in 1950 was estimated at 9.2 million dollars. Because of the high per-acre value of these crops, intensive management is practiced in an effort to produce maximum yields of high quality flowers and bulbs at minimum costs.

One of the more common methods of analysis for 2,4–dichlorophenoxyacetic acid (2,4,–D) is the one using chromotropic acid as the color developing reagent (1). In this laboratory it was found that it was difficult to obtain relatively pure chromotropic acid or its disodium salt. As an approach to the preparation of a purer compound, several experiments were tried.

An announcement has been received of the Crop Protection and Pest Control Exhibition to be held at the Royal Horticultural Society's New Hall, London, England, May 12 to 15, 1958. Further information can be obtained from John Wheatley, The Crop Protection and Pest Control Exhibition, Leonard Hill House, Eden Street, London, N. W. 1.