The control of undesirable woody plants is one of the biggest land management problems on non-crop land in the South. There are more than six million acres of pine sites in Louisiana alone that are in need of cull hardwood control (12). Large acreages of similar stands and sites are located in other southern states. Because of the competition for land and increased demand for raw materials, many landowners have realized the necessity of utilizing their land to the fullest extent.

Foliar application of herbicides, plant regulators, and nutrients is a well established practice. Yet, the many contradictory reports in the literature (7) indicate that the routes of entry into and movement within leaves are not clearly known. This situation has probably arisen because presently available techniques do not precisely establish the location of the penetrant on the cellular level.

In tests conducted at Prosser, Washington, during 1955 and 1956, DCB (orthodichlorobenzene), alone or in combination with xylene, showed considerable promise for controlling submersed aquatic weeds when introduced into irrigation channels. The first objective of the experiment reported herein was to determine whether irrigation water treated with DCB or DCB-xylene mixtures would injure certain crop plants. In other tests amitrol (3–amino–1,2,4–triazole) and sodium salt of dalapon (sodium 2,2–dichloropropionate) were effective in controlling certain emergent aquatic and ditchbank weeds. Frequently, the application of herbicides to control such weeds results in inadvertent or unavoidable contamination of water used to irrigate crop plants. Consequently, a second objective of this investigation was to determine the approximate quantities of amitrol and sodium salt of dalapon required to injure certain crop plants when applied in irrigation water, and to study the symptoms of injury.

Ethyl N,N-di-n-propylthiolcarbamate (EPTC) has shown promise as a pre-emergence herbicide in both greenhouse and field studies. Antognini reported that EPTC was quite volatile. In volatility studies in this laboratory the loss of unformulated technical EPTC from a free liquid surface was 57 micrograms/sq cm/hr at 30° C. It was difficult to understand how a compound as volatile as EPTC could be an effective pre-emergence herbicide. Preliminary tests, utilizing radioactive EPTC, demonstrated that it was less volatile from soil surfaces than from stainless steel or leaf surfaces, indicating that a soil adsorption phenomenon might be involved. Greenhouse studies showed that at a given concentration of EPTC in the soil the phytotoxicity to oats (Avena sativa L.) was not the same in the various soil types studied. The purpose of this study was to investigate the relationship between soil adsorption of EPTC and oats injury in several soil types.

In 1955, three British workers (2) described a variable dosage sprayer which was designed for large field plots. The original description did not attract much attention in the United States when it was first published, but the principles described therein are receiving more attention at the present time, both in this country and abroad (1).

One of the factors to be considered in the establishment and maintenance of an orchard is the competition from weeds for the available supply of moisture and nutrients. Mechanical elimination of competitive plants is time consuming, expensive, and may not be done as early or as frequently as it is needed each year. The use of herbicides as a supplement to such a program now seems worthy of serious consideration. In some instances, as will be seen below, the use of mechanical methods may be eliminated altogether.

The chlorinated phenoxyalkylcarboxylic acids are extremely valuable in affording a solution to many weed problems. On the other hand, the use of such herbicides may create problems since many crop or ornamental plants which are very sensitive to the phenoxy herbicides may be growing in close proximity to crops or areas in which treatments with such herbicides seems desirable. In the South, cotton may be planted adjacent to crops such as rice, sugarcane or corn or in areas bordering woods, highways or railways. On such areas, the application of phenoxy herbicides may solve the problem of weed control; however, they may create a new problem by causing injury to cotton.

Halogenoalkylcarboxylic acids such as monochlorocetic acid, trichloroacetic acid, dichloropropionic acid and 2,3–dichloroisobutyric acid, have well known herbicidal activities upon monocot plants. However, they are not effective in killing the seeds of weeds. This may be due to their inability to penetrate the seed coats.

Wild garlic (Allium vineale L.) continues to be an important problem weed of Eastern and Southeastern United States. It is spread principally by aerial bulblets mixed with seed. The present rules and regulations used by seed laboratories to determine bulblet viability seem inadequate. This paper will discuss the use of 2,3,5–triphenyltetrazolium chloride, referred to as TZ, as an indicator of bulblet viability.

Interest in the substituted urea compounds for their herbicidal properties was precipitated by Bucha and Todd's (3) report that 3–(p–chlorophenyl)–1,1–dimethylurea (monuron) was extremely phytotoxic. Freed (6) reported that only asymmetrically substituted ureas are effective as herbicides. Substitution on the para position was reported to result in greatest activity followed by meta. An ortho substitution reduced activity to half or less than that of the comparable para substitution.

The chemical nomenclature used in connection with herbicidal compounds is frequently difficult for individuals who have little training in chemistry. A large molecular model has been constructed as a visual aid to facilitate audience comprehension of chemical nomenclature and to demonstrate relationships between chemical structure and herbicidal activity. The present model is designed to illustrate four of the major classes of herbicides, but it can be further modified in design to illustrate other herbicide classes.

Because nut grass is a weed problem, there is need for knowledge of the factors affecting the sprouting of tubers following conditions in which they are dormant. Similarly an understanding of the mechanisms involved in the control of dormancy along with information on the metabolism of tubers at different stages of growth is needed. The purpose of this series of studies was to obtain information on some of those problems. The purpose of the present study was to determine the response of nut grass to several oxygen levels as measured by germination habits and respiration of tubers.

Goosegrass, a widely distributed annual weed, creates difficult problems in heavily used turf areas. The seriousness of this weed problem, especially on golf course greens and tees, has suggested studies for its control. Very little research has been conducted in regard to this grass. Germination studies by Toole and Toole3 showed that 0.2% potassium nitrate was superior to water when used to moisten the substratum. Their work also indicated exclusion of light had little effect on germination at alternating temperatures of 20°–30°. The present study includes more complete temperature and light comparisons, and attempts to demonstrate light and temperature effects on seed germination.

The high cost and scarcity of farm labor and the realization that the control of weeds with chemicals is possible and economical has resulted in greater demand for up-to-date information from all those concerned with weed control. For those charged with the responsibility of research in weed control chemicals and techniques, the additional duties of extension teaching and “trouble shooting” can be burdensome if not properly handled.

The value of 2,4–dichlorophenoxyacetic acid (2,4–D) for control of broadleaved weeds is well known. It is equally well known that these chemicals can cause serious damage to certain crops. After 10 years of general use in agriculture it is well to review the extent to which 2,4–D has been a source of trouble and to examine regulatory policy with regard to 2,4–D.

To obtain information on the metabolism of nut grass tubers at different stages of growth, this study purposed to determine certain metabolic pathways of tubers at different stages of germination, which might aid in determination of the most sensitive stage to herbicides.

The possible use of the phenoxybutyric acids as selective herbicides in the pea crop has been recognized from the beginning of their development (3) and preliminary experiments with the more important compounds of this series carried out in 1954 indicated that 4–(2–methyl–4–chlorophenoxy)butyric acid [4–(MCPB) showed the most promise (1). To date no results have been reported on the persistence of MCPB in peas; experiments were, therefore, undertaken to determine this under field conditions.