When vapor losses of isopropyl N-phenylcarbamate (IPC) and isopropyl N-(3-chlorophenyl)carbamate (CIPC) were studied under controlled laboratory conditions using a direct-trap for vapors, IPC proved more volatile than CIPC. Temperature, air-flow rate, moisture, and cation exchange capacity of soil were important factors influencing volatility. Vapor loss increased with increasing air-flow rate and temperature; losses from moist soil decreased as the percent clay, organic matter, or both, and the exchange capacity increased. Vapor losses were negligible from spray applications on dry soil but were sizable from soils at field capacity which were similar to those from soils saturated with moisture. Vapor losses of IPC from granules were much higher than from a surface spray, and CIPC losses were about the same for the granules as from the spray. Covering the soil-applied herbicide with ⅛ to ¼ in of soil was effective in reducing vapor loss.

Under light grazing, the reproductive capacity of wild carrot (Daucus carota L.) was reduced, but on pastures under heavy grazing, cattle prevented regrowth and seed production of flowering plants. To simulate the effects of cattle grazing, seedlings and flowering plants were clipped at different times during the summer on natural and experimental plots on different soil textures. Plants on fine textured soils were larger in size, regenerated more rapidly, and had a higher survival rate after clipping. The most efficient time for control by a clipping treatment, determined on the basis of prevention of seed production and mortality of plants, was in the latter part of August.

The role of corn (Zea mays L.) var. Dixie 18, sorghum (Sorghum vulgare) var. RS 610, and Johnsongrass (Sorghum halepense L.) in dissipation of 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) from Norfolk sandy loam was studied in the field and in a pot-culture experiment in the greenhouse. Atrazine residues were determined by both chemical and bio-assay methods. Corn and Johnsongrass field plots had significantly less atrazine remaining in the 0- to 6-in depth than similarly treated fallow plots 1, 2, 3, and 6 months after planting, and the crops were equally effective in dissipating atrazine from soil. Soil in pots cropped with corn, sorghum, or Johnsongrass had significantly less atrazine remaining than in uncropped pots. Uptake by corn, Johnsongrass, and sorghum within 3 months in the pot-culture experiment accounted for losses of approximately 25, 25, and 20%, respectively, of the herbicide initially present. Bio- and chemical assays were equally sensitive methods of determining atrazine in the soil and gave similar results.

The loss of 2-chloroallyl diethyldithiocarbamate (CDEC) from the dry surface of four soils was followed over a 24-hr period by spectrophotometric procedures. As the temperature was in creased from 31 C to 44 C and to 54 C, average losses from all soils increased from 33 to 47 to 54%, respectively. There was relatively little difference in rates of loss from the different soils. Loss at 44 C at low (20%) and moderate (65%) relative humidity generally was similar in magnitude. Losses from a wet soil surface at 44 C were much more rapid than from a dry soil.

The herbicide 2,6-dichlorobenzonitrile (dichlobenil) was quite persistent in cranberry bogs. The chemical was not readily leached downward in the soil nor carried from the bog by flood water but was recovered primarily in the upper 4 in of the soil. Chemical residue analysis demonstrated a greater quantity of herbicide was present than indicated by a bio-assay test. Most of the herbicide is believed to be held ineffective by the organic matter in the soil.

Barnyardgrass (Echinochloa crusgalli (L.) Beauv.) emerged in fields as early as May 3. The shortest period between seeding and emergence and between emergence and tillering was during the warmest period of the growing season. The number of days from emergence to heading and maturity decreased progressively for later seedings. The height of plants was greatest when the plants emerged early in the growing season. The highest number of tiller and heads per tiller were produced by plants emerging in July. Plants which emerged in May and June produced the highest yields. Barnyardgrass seedlings grown under 11-hr photoperiod and 16-hr photoperiod produced mature seeds in 52 and 84 days, respectively. Barnyardgrass grew best under wet soil moisture conditions.

Some factors affecting the absorption and translocation of radioactive 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) in blackjack oak (Quercus marilandica Muench.) were studied. Absorption of 2,4,5-T was less in plants treated late in the growing season than in those treated earlier. Absorption and translocation of 2,4,5-T were inversely related to soil moisture stress. Increases in the rate of application from 10 to 50 μg of 2,4,5-T per plant caused a decrease in absorption and translocation, but decrease of the latter did not occur until the rate was increased above 25 μg/plant. Translocation was highest in June and was higher from the leaves of mature plants than from young regrowth.

Herbicides were evaluated for weed control in seedling perennial grass stands at six locations in eastern Washington. Most annual weeds commonly found in grass seed fields were controlled by 2-methoxy-3,6-dichlorobenzoic acid (dicamba), 2,3,6-trichlorobenzoic acid (2,3,6-TBA), and 1-butyl-3-(3,4-dichlorophenyl)-1-methylurea (neburon). Dicamba was the most effective herbicide for annual weed control but caused some injury to Kentucky blue-grass seedlings. Seedling grasses injured by dicamba recovered and became established in each trial. Grasses were injured about the same extent when treated with 2,3,6-TBA as when treated with dicamba, but 2,3,6-TBA did not control as many weed species. Neburon did not control as many species as dicamba and 2,3,6-TBA but was effective in killing a large number of species without measurable injury to grass seedlings.

N-1-naphthylthalamic acid (NPA), 3-amino-2,5-dichlorobenzoic acid (amiben), and the dimethyl ester of 2,3,5,6-tetrachloroterephthalic acid (DCPA), in granular and liquid or wettable powder formulations, were applied to the soil and then activated by either overhead or sub-irrigation.

Granular formulations of the herbicides were as effective as liquid formulations for weed control, providing there was ample moisture for activation. High temperatures and dry soils were conducive to losses by volatilization of NPA. DCPA underwent less loss by volatilization at high temperatures. Both overhead and sub-irrigation were effective in activating these herbicides, but overhead generally was more effective. Under sub-irrigation, use of a granular carrier was more effective with a volatile herbicide. Formulation differences decreased in importance under overhead irrigation. Under conditions of high temperatures and soil moisture, soil persistence of the herbicides varied inversely with their volatility.

Gypsophila paniculata L., a dicotyledonous, herbaceous member of the Caryophyllaceae, was introduced into North America from Eurasia as a garden ornamental and has escaped to become troublesome in some areas. A life history study has revealed that this species is spread entirely by seed, its tumbleweed character being an important factor. Germination occurs mainly in the spring in Saskatchewan stands, perhaps as a result of no dormancy in the seeds. Although seedling development is characterized by a rapid penetration of the root system, mortality in natural stands is high. Under favorable conditions, at least 2 yr are required for the production of floral primordia. The mature plant is characterized by a root system which penetrates to depths of 4 meters or more. Shoots arise each year from a thick woody caudex.

The herbicide 3-amino-2,5-dichlorobenzoic acid (amiben) was converted to N-(3-carboxy-2,5-dichlorophenyl)-glucosylamine, N-glucosyl amiben, in roots of plants treated with amiben. Identification of N-glucosyl amiben was accomplished by means of thin-layer and gas chromatography and confirmed by infrared spectroscopy. The postulated metabolite was synthesized and found to be identical with the product of amiben metabolism in plants.

Most of the 3-amino-2,5-dichlorobenzoic acid (amiben) absorbed by treated plants was converted to N-glucosyl amiben in the roots. Only small amounts of amiben and N-glucosyl amiben occurred in stems and leaves. The N-glucoside was not metabolized further and remained in vegetative tissue of soybeans for at least 50 days. Soybeans which were depleted of carbohydrate reserves by starvation in the dark absorbed less amiben and produced less N-glucosyl amiben than did plants treated under normal illumination. A similar trend was noted for tomato plants treated in a comparable manner.

Seeds of Striga asiatica (L.) Kuntze were induced to germinate with a stimulant from host exudates in the presence of a water-soluble germination inhibitor extracted from Striga seeds. Germination obtained was dependent upon the relative concentrations of stimulant and inhibitor present in the germination medium. The inhibitor had no effect on radical elongation of Striga seeds that germinated in its presence.

The maleic hydrazide-30 treated plants increased in protein hydrolysate significantly over the controls, without having any growth. Therefore, this suggests that the synthesis of protein and metabolism of amino acids is not directly related to growth in tea (Camellia sinensis). The inhibitory effects may be due to the lack of synthesis of growth hormones responsible for cell enlargement, or may have a direct effect on the cell wall, reducing the cell plasticity. Hydrolysis with 6N HCl causes a significant destruction of amino acids.

A discussion is presented on some mechanisms whereby certain plant growth-regulating materials may exert their activity on plants. A discussion of photosynthesis is developed on the basis of two light reactions being involved in the photosynthetic process. Herbicides which may be active in photosynthesis are considered in relation to their site and mode of action. Current theories of nucleic acid metabolism and protein synthesis are presented and certain inhibitors of these processes are discussed and the possible involvement of plant growth-regulators is considered.

This is a most timely question because of the importance of herbicides in modern agriculture, the quantity of resources in industry and the public institutions devoted to testing, and the sizeable number of new materials appearing each year. Before examining the role of the experiment stations in herbicidal testing, let me make clear that I am restricting my comments to known materials. Testing so-called unknown materials to identify potential herbicides is clearly incompatible with the teaching and research role of a university. Such research, if it may be called research, is oriented to products whereas the stations' applied research in this area should be oriented to problems faced by the agriculture and homeowners of the state.

All will agree testing is necessary to determine if a herbicide will do the job under local conditions. In brief, the present program involves: (1) screening for herbicidal activity and preliminary determination of effective rate and crop tolerance by industry; (2) research by university personnel on rate and method of application and on crop tolerance, and; (3) demonstrations or field tests by university and industry personnel to further test the material and to promote use of it by farmers. There is some duplication among these three. Furthermore, steps 2 and 3 are essentially repeated in each state having the particular weed and crop situation. Yet, we find that recommendations among these states are frequently the same. Where this is the case, it is apparent that all states need not have done the testing. In view of this duplication and of changes taking place in universitites and the pesticide industry, an honest appraisal of the overall testing program and of stations' role in it seems in order. Let us look at some of the things which bear on the stations' involvement in testing programs.

In the past, Agricultural Experiment Stations have routinely evaluated new herbicides and other pesticides to determine their potential place in solving local agricultural problems. This type of work has become very controversial in recent years. Many universities will no longer work with herbicides during the evaluation stages on field problems and limit most or all of their herbicide research to more basic laboratory oriented programs. Since Oregon State University has a major project on the evaluation of new herbicides, there must be some justification for this in a university's work program. An effort will be made to point out some of the reasons for the Oregon State University program and try to analyze the pros and cons of this topic from the university standpoint.

Several steps are possible in testing herbicides, or what might be called steps in testing during the herbicide development period. The first step will be called early evaluation of new products. The advantages for a university becoming involved in this early phase testing work is that it builds a close working relationship with the chemical industry. This working relationship provides support for students, which in itself is important to the future of the weed control field. There is deep concern over the small number of students that are being trained in weed control, particularly those that are agriculturally oriented. If some change is not made in the lack of sufficient numbers of trained students from universities, a serious crisis in both industry and university staffing will result.

As a representative of the chemical industry, this subject is a rather difficult one to discuss. When one stops a moment to think about the role of the university in herbicidal testing, immediately he realizes that this probably never has been defined and it appears for the most part the administration and research personnel of each university follow the road that is the best of their liking. Far too often, they do not stop and ask themselves whether they really are taking the proper route.

In discussing this topic, one can take the approach that all universities, and some are in this category, are doing an excellent job and compliment everyone that an adequate job is being done. Or one can conclude that the universities should not be doing field evaluations (and please understand this is in the minds of a few university administrators) or the answers to the field problems can be solved in the laboratories; or finally, one can conclude that the universities are not doing a proper job and that considerable improvement must take place. Perhaps I will make some new enemies today (although the Chairman, Dr. Ries, indicated I could take any approach I preferred), but I am of the opinion that our university and experiment station system primarily is not doing a proper job in testing herbicides and that they must take a more active role in the future than they have in the past.