The Beatitudes could well be extended to bless those who continue to pursue learning aggressively throughout their life, for surely such individuals shall be confronted with challenge and their days shall be full of wonderment and accomplishment and self-satisfaction. As I reflect on this business of learning, it is apparent that a great deal of it takes place at the subconscious level. Throughout all of my undergraduate and graduate student days and ever since through affiliation with knowledgeable associates, the concept of professionalism seems to have been taking shape for me as an individual. Perhaps it is well at this juncture in the life of WSSA to consider what professionalism means for the discipline of weed science.

We hear the expression “cost-benefit” a great deal nowadays; and when we do, we should always ask “cost to whom? Benefit to whom?” We should also remember that cost-benefit analysis requires that account be taken not only of financial gains and losses but also of all advantages and disadvantages of any kind. Consideration only of income and expenditure is investment appraisal, and many of the so-called “cost-benefit” studies of herbicide usage which have been published come into this category. Such studies are useful, but they should not be considered in isolation from investment appraisal of herbicide discovery, development, and production for the manufacturer; and both must be integrated into a total view of cost-benefit of weed control for the whole community, a broad and long-term view which takes account not only of economic values but also of social values. To make decisions and to formulate policies which will set herbicides in an optimum way in the social and economic context of an entire community and which will produce the most favourable cost-benefit for that whole community demands study and analysis of the total system. In the short time allocated to me I can do no more than skim over this wide field and indicate a number of relevant topics, and I plead guilty in advance to the charge of being superficial and of suggesting things that should be done without describing in detail how they could be done. My remarks will apply to the developed countries because the herbicide needs of the under-developed countries are a separate subject.

I am pleased to be with you today at this 13th meeting of the Weed Science Society of America. As the president of this organization, Dr. Upchurch, has noted, this event is an excellent mechanism for an exchange of ideas between the various disciplines in the field of weed science. It also allows today for me an opportunity to express to you the view of the Environmental Protection Agency with respect to agriculture in general and pesticide herbicide questions in particular, by a discussion of the new Environmental Pesticide Control Act.

The effect of soil temperature, soil moisture content, and soil bulk density on the diffusion of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], propachlor (2-chloro-N-isopropylacetanilide), and diazinon [O,O-diethyl O-(2-isopropyl-6-methyl-4-pyrimidinyl) phosphorothioate] in Ida silt loam soil was studied in the laboratory. Diffusion coefficients of 1.90, 1.36, and 0.63 mm2/day at 27 C for propachlor, atrazine, and diazinon, respectively, show in a relative way the expected movement of these chemicals in Ida silt loam soil. The greatest amount of movement occurred with high temperatures and high moisture contents. Soil moisture had more effect on atrazine movement than on propachlor movement, and very little effect on diazinon movement. Movement for all chemicals decreased with an increase in bulk density.

The effect of 3,6-dichloro-o-anisic acid (dicamba) on common purslane (Portulaca oleracea L.) was studied under growth room conditions. Common purslane was quite sensitive to dicamba. The lethal rate depended on the age of the plants and increased with their development. The visual responses included bending of young stems, epinasty of leaves, and inhibition of nyctinasty, followed by necrosis of leaves, defoliation, swelling of stems, and death of the growing tips with loss of apical dominance. Stem elongation was inhibited and fresh weight of tops was markedly reduced by dicamba application to either the roots or foliage. Carboxyl-labeled dicamba-7-14C was absorbed slowly by common purslane leaves. However, translocation appeared rapid, with accumulation of dicamba observed in the young tissues. A small amount of dicamba was exuded through the roots. There was no indication of dicamba degradation in common purslane during 8 days following treatment.

The fungicide, Dyrene [2,4-dichloro-6-(o-chloroanilino)-s-triazine], severely injured var. mite of Canada thistle [Cirsium arvense (L.) Scop.]; and the damage resembled that caused by bipyridylium herbicides. Regrowth from treated plants was abnormal. Other arylamino-s-triazines were from slightly to severely phytotoxic to leaf sections of the var. mite. The var. horridum of Canada thistle was not affected by Dyrene or related compounds. Dyrene and metabolites of Dyrene which were phytotoxic to var. mite leaf disks in bioassay tests were isolated from treated var. mite and horridum plants, but none of these compounds injured the var. horridum. One metabolite was found only in the var. mite; the other five occurred in both varieties. The metabolites were apparently formed from Dyrene by conjugation reactions.

Dicamba (3,6-dichloro-o-anisic acid) dissipated in 4 weeks and in 9 to 16 weeks when sprayed on grassland soils of Texas at 0.28 kg/ha and 0.56 kg/ha, respectively. At three of four locations ranging from humid to semiarid and from clay to sandy loam and sampled from 9 to 63 weeks after treatment, usually residues were no deeper than 120 cm and never deeper than 150 cm. However, dicamba residues were detected 120 cm deep 53 weeks after application of granules at 1.68 or 2.24 kg/ha to sand of semiarid grassland. Since dicamba sprays are usually applied at 0.56 kg/ha or less for grassland restoration in Texas, it is unlikely that residues of dicamba will persist in soil through the growing season from spring applications.

A laboratory procedure for evaluating the effect of pesticides on nitrification in soil proved to be simple to perform, reproducible, and offers a procedure for rapid screening of a large number of chemicals in a short period. The recovery of added nitrate by extracting with distilled water was essentially 100% complete. The conversion of added ammonium to nitrate by the soil microorganisms was nearly complete after the 2-week incubation period. Nitrification in soil treated with several different herbicides and insecticides was determined by our procedure. A nitrification inhibitor, N-Serve3 (2-chloro-6-trichloromethyl pyridine) was included as a standard. None of the herbicides or insecticides inhibited nitrification and the N-Serve completely inhibited nitrification during the 2-week incubation.

Established stands of alfalfa (Medicago sativa L. ‘Lahontan’) at six field locations were treated with soil-active herbicides during the dormant period for the control of winter annual weeds. Weeds and alfalfa were hand separated at the first harvest. This forage, which varied widely in weed content, was analyzed for protein. The percentage of protein correlated negatively with weed content in all cases. Analyses of covariance revealed that the direct effect of the herbicides on protein content was either small or absent and that the primary cause of the negative correlations was weed content.

Herbicidal oil emulsions and herbicidal naphthas were applied repeatedly as postemergence treatments to cotton (Gossypium hirsutum L., ‘Stoneville 7A’) in field investigations over a 4-year period. Postemergence directed applications of high aromatic oils emulsified with water were effective for selective weed control in cotton. Oil emulsions did not cause stem girdling when applied to cotton at any growth stage. Herbicidal naphthas effectively controlled weeds but caused stem girdling when applied after the cotton was 4 weeks old.

Experiments were conducted to compare the drift of low-expansion foam and conventional sprays in a low-speed horizontal wind tunnel under controlled environmental conditions. Dimensions of the tunnel were 1.30 m high, 0.61 m wide, and 7.32 m long. Wind speed was maintained at 1.52 m/sec. Drift was compared for spray solutions, with and without foam adjuvants, using several different types and sizes of air-inducting nozzles and three sizes of conventional fan nozzles. Large drops produced by the air-inducting nozzles, with and without foam adjuvant, resulted in significantly less drift beyond 1.83 and 6.10 m than sprays from the conventional fan nozzles. The addition of foam adjuvant to the spray solution resulted in increased drift beyond 1.83 m for sprays from the air-induction nozzles in several comparisons but did not result in a significant increase in the drift beyond 6.10 m.

This investigation was initiated in 1954 at Beltsville, Maryland, to determine the initial and long-term response of vegetation to, and persistence of, massive quantities of herbicides. Vegetative responses were determined 1, 2, 3, and 15 years after treatment. Residual phytotoxicity and herbicide residues were determined 14 years after treatment with bioassay and chemical analysis. After 3 years, revegetation was nearly complete in plots treated with massive (up to 400 times recommended agricultural rates) quantities of fenuron (1,1-dimethyl-3-phenylurea), monuron [3-(p-chlorophenyl)-1,1-dimethylurea], dalapon (2,2-dichloropropionic acid), chlorpropham (isopropyl m-chlorocarbanilate), sodium chlorate, 2,4-D [(2,4-dichlorophenoxy)acetic acid], borax, sodium chlorate plus borax, and 2,4-D plus borax. Only diuron [3-(3,4-di chlorophenyl)-1,1-dimethylurea], DMU [3-(3,4-dichlorophenyl)-1-methylurea] sodium arsenite, and sodium arsenite plus sodium chlorate gave residual control of vegetation for more than 3 years. Revegetated plots were identical to untreated check plots whether the vegetation was initially killed by chemical or mechanical methods. Phytotoxic soil residues of DMU, diuron, and arsenate were present 14 years after application.

Field experiments were conducted from 1967 to 1971 to determine the influence of incorporation and time of application on the performance and persistence of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Both grass and broadleaf weeds were effectively controlled by atrazine on all dates of application. Both the 2.8 and 5.6 kg/ha rates were effective as preplant incorporated or preemergence treatments. Persistence of atrazine did not differ with respect to method of application. Applications of atrazine made in April and May were degraded more rapidly than were applications made in February and March. Loss curves generally corresponded to a first-order reaction with atrazine showing an average half-life of 20 days from February to July.

The adsorption-desorption equilibria of chlorbromuron [3-(4-bromo-3-chlorophenyl)-1-methoxy-1-methylurea] in soil conformed to the Freundlich equation. Values of the constants, k and n, ranged from 4.2 to 12.3 and from 1.2 to 2.5, respectively, in eight soils. No significant linear correlation was detected between the Freundlich k values and soil texture, organic-matter content, pH, or water-holding capacity. Degradation studies were conducted using 14C-carbonyl-radiolabeled chlorbromuron in soil incubated at 18 or 32 C, with and without prior autoclaving, and with and without glucose enrichment. Degradation was enhanced by the higher temperature and glucose amendment, and it was retarded by autoclaving. Thin-layer chromatography indicated no accumulation of the monomethyl or monomethoxy derivative of chlorbromuron in any of the treatments. Chlorbromuron degraded rapidly in the incubation studies. Rapid loss of phytotoxicity was also noted in a greenhouse study with cucumber (cucumis sativus L. ‘Explorer’) bioassay. Phytotoxicity from 4 ppmw chlorbromuron had diminished to a very low level after 12 weeks.

Herbicides were evaluated for selectivity between three tall coarse grasses and three short fine grasses. Reed canarygrass (Phalaris arundinacea L.), quackgrass [Agropyron repens (L.) Beauv.], and smooth brome (Bromus inermis Leyss) were consistently more susceptible to amitrole-NH4CN (3-amino-s-triazole-ammonium thiocyanate) than three desirable short grasses, Kentucky bluegrass (Poa pratensis L.), creeping red fescue (Festuca rubra L.), and redtop (Agrostis alba L.). Reed canarygrass and redtop were more susceptible to dalapon (2,2-dichloropropionic acid) than creeping red fescue. Amitrole-NH4CN and dalapon combinations were more toxic to reed canarygrass, smooth brome, and redtop than creeping red fescue. Pyriclor (2,3,5-trichloro-4-pyridinol) was quite toxic to all grasses with Kentucky bluegrass showing the most tolerance. When TCA (trichloroacetic acid) was combined with amitrole-NH4CN results were similar to the dalapon combination but overall toxicity was reduced.

Honey mesquite [Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockerell], huisache [Acacia farnesiana (L.) Willd.], Macartney rose (Rosa bracteata Wendl.), live oak (Quercus virginiana Mill.), and whitebrush (Aloysia lycioides Cham.) were sprayed with herbicides alone and in mixtures. Mixtures of picloram (4-amino-3,5,6-trichloropicolinic acid) + dicamba (3,6-dichloro-o-anisic acid) at 0.56 + 0.56 and 1.12 + 1.12 kg/ha were most effective for killing honey mesquite in July. Picloram or picloram + dicamba were more effective for defoliating huisache than 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid], dicamba, or other mixtures of herbicides. On Macartney rose picloram as the salt or ester was most effective, but some mixtures of picloram plus either 2,4-D [(2,4-dichlorophenoxy)acetic acid] or 2,4,5-T were as effective as picloram alone. On live oak, the most effective treatments generally contained at least 1.12 kg/ha of picloram either alone or in mixtures with dicamba or 2,4,5-T. Picloram alone killed as many or more whitebrush plants than MCPA [[(4-chloro-o-tolyl)oxy]acetic acid], dicamba, 2,4,5-T, 2,4-D, or mixtures.

Treatments were applied to heavily infested johnsongrass [Sorghum halepense (L.) Pers.] in the field for 3 years. Half of each treated plot was cultivated 5 weeks after planting soybeans [Glycine max (L.) Merr.]. Dalapon (2,2-dichloropropionic acid) applied to johnsongrass foliage 7 to 10 days before plowing plus either of the following three preplant incorporated herbicides, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], or vernolate (S-propyl dipropylthiocarbamate), gave 85, 68, and 82% johnsongrass control, respectively, at the end of a 3 year study. The preemergence incorporated herbicides applied following plowing and two diskings resulted in poor (35 to 50%) johnsongrass control with significant yield reductions in 2 of the 3 years. When the preemergence incorporated herbicides were applied following two diskings and eight rototillings, johnsongrass control was 62% after 3 years which was significantly less than the 79% control resulting from dalapon plus preemergence herbicides. Cultivation 5 weeks after planting soybeans increased johnsongrass control 22, 35, and 36% and soybean yields 439, 370, and 320 kg/ha in 1969, 1970, and 1971, respectively, over comparable plots without cultivation.

Trumpetcreeper [Campsis radicans (L.) Seem.] grown from 10-cm root sections was more susceptible to foliar applications of 2,4-D [(2,4-dichlorophenoxy)acetic acid] and dicamba (3,6-dichloro-o-anisic acid) than trumpetcreeper grown from 45-cm root sections. Dicamba controlled trumpetcreeper better than did 2,4-D, particularly trumpetcreeper grown from 45-cm root sections. More 14C-dicamba than 14C-2,4-D was absorbed through the foliage and translocated to the roots of trumpetcreeper grown from 10-cm roots. No 14C-2,4-D was detected in the 45-cm roots; however, 14C-dicamba was recovered from both the upper and the lower sections of the 45-cm roots.

Qualitative and quantitative oil content of corn (Zea mays L.) kernels as influenced by herbicides was measured by gas-liquid chromatography. Alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl) acetanilide] at 0 to 6.7 kg/ha, atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 0 to 5.6 kg/ha, linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] at 0 to 3.4 kg/ha, prometryne [2,4-bis(isopropylamino)-6-(methylthio)-s-triazine] at 0 to 3.4 kg/ha, and cyanazine [2-[4-chloro-6-(ethylamino)-s-triazine-2-yl]amino-2-methylpropionitrile] at 0 to 7.8 kg/ha were evaluated. Oil quantity was not greatly influenced by any of the herbicides; however, percentage corn oil fatty acid composition was altered to a minor but statistically significant degree by each of the herbicides. The use of alachlor, cyanazine, atrazine, linuron, or prometryne on corn at recommended rates or at rates greater than currently recommended field application rates did not induce serious changes in either total oil content or fatty acid distribution in corn.

The competitiveness of annual weeds in irrigated sweet Spanish onions (Allium cepa L.) was studied at North Platte, Nebraska, during 1969 and 1970. Weeds allowed to grow in the row for 2, 4, 6, and 8 weeks after onion emergence reduced onion yields 20, 20, 40, and 65%, respectively. When plots were kept weed-free until onion emergence and 2, 4, 6, 8, 10, and 12 weeks after emergence, onion yields were reduced 100, 99, 87, 75, 46, 25, and 5%, respectively. Redroot pigweed (Amaranthus retroflexus L.), kochia (Kochia scoparia L.), and grass weeds accounted for 54, 21, and 21%, respectively, of the total weed yield.