Sequential application of cycloate (S-ethyl N-ethylthiocyclohexanecarbamate) at 3.4 kg/ha, phenmedipham (methyl m-hydroxycarbanilate m-methylcarbanilate) at 1.1 kg/ha, and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0.6 or 0.8 kg/ha, plus certain mechanical measures, controlled weeds during all periods of the growing season without significant injury to sugarbeets (Beta vulgaris L.). Early-season weed control was complete enough that the new selective mechanical thinners could have replaced labor for thinning. The additional labor required to bring the crop to harvest free of weeds was limited to one late-season hoeing, which required less than 10% of the total labor required in traditional weed control schedules without herbicides.

Competitiveness of three high-yielding, lodging-resistant rice (Oryza sativa L.) cultivars with barnyardgrass [Echinochloa crus-galli (L.) Beauv.] was compared during 3 years at Stuttgart, Arkansas. ‘Starbonnet,’ ‘Nova 66,’ and ‘Bluebelle,’ which matured in 145, 135, and 125 days, respectively, competed with barnyardgrass for periods ranging from 10 days after crop emergence to all season. ‘Starbonnet’ was the most competitive and ‘Bluebelle’ was the least. Barnyardgrass competition for 10 or 20 days did not reduce grain yields of any cultivar. Weed competition for 40 days or longer reduced yields of ‘Nova 66’ and ‘Bluebelle,’ and competition for 60 days or longer lowered yields of ‘Starbonnet.’ As the period for maturity increased, each cultivar competed more effectively with barnyardgrass.

Five 2,5-dimethyl-1-pyrrolidinecarboxanilides were effective inhibitors of the Hill reaction. However, only the cis isomers were active; the trans isomers were totally inactive. Experiments were conducted using 14C-5328 (cis-2,5-dimethyl-1-pyrrolidinecarboxanilide). A correlation existed between resistance of various plants to 5328 and their ability to metabolize it to water soluble metabolites. Velvetleaf (Abutilon theophrasti Medic.) and proso millet (Panicum miliaceum L.) seedlings were very susceptible to 5328 and were unable to metabolize it. Tall morningglory [Ipomoea purpurea (L.) Roth] seedlings were highly tolerant to 5328 and converted it completely to its metabolites. Corn (Zea mays L. ‘DeKalb variety XL-45′) seedlings which were slightly susceptible to 5328 injury were able to metabolize up to 90% of the parent compound. Corn foliage uptake of 14C-5328 applied to the soil surface occurred through the adventitious roots.

Field and greenhouse studies were conducted on S-21634 (1-methyl-4-phenylpyridinium chloride) for control of purple nutsedge (Cyperus rotundus L.) and tolerance of several turfgrass varieties and species. Purple nutsedge was controlled during the initial year of treatment with single applications of 3.4 and 5.6 kg/ha rates. All turfgrasses were injured following treatments, however, all except centipedegrass [Eremochloa ophiuroides (Munro) Hack.] had recovered in 7 to 8 weeks. In general, the injury to centipedegrass was higher and the turf density was lower in the treated plots at the final ratings. None of the treatments applied as a single S-21634 application affected root growth of bermudagrass (Cynodon sp.), ‘Emerald zoysia’ (Zoysia japonica x Z. teniuflolia), centipedegrass, St. Augustine grass [Stenotaphrum secundatum (Walt.) Kuntze], or tall fescue (Festuca arundinacea Schreb, ‘Ky 31′).

Canada thistle (Cirsium arvense L.) plants containing one elongated and one recently emerged shoot from the same root segment were treated with 14C-ring labeled atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Fourteen days after atrazine application to the elongated shoot 98% of the recovered activity remained in this shoot. The distribution pattern of 14C suggested movement with the transpiration stream. Of the 14C in the treated shoot, 82% was in the form of unaltered atrazine at 14 days after application. Greenhouse studies with nonlabeled atrazine indicated that this herbicide had only an indirect effect on portions of the plant located basipetally to the area of application.

Three poisonous varieties of timber milkvetch (Astragalus miser Dougl. ex Hook.) were grown under different temperature regimes in growth chambers. Miserotoxin, the poisonous chemical in timber milkvetch, was in greater concentration in plants grown at higher day temperatures (32 C) than at 24 C. In the field, nitrogen fertilizers did not affect miserotoxin synthesis in any variety, but significantly increased plant nitrogen in two varieties. Excluding light from Yellowstone milkvetch [var. hylophilus (Rydb.) Barneby] for 2 weeks significantly lowered miserotoxin concentration. Miserotoxin level in timber milkvetch was reduced when photosynthesis (a) was blocked by subjecting plants to prolonged darkness; (b) was disrupted by treating plants with 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] or silvex [2-(2,4,5-trichlorophenoxy)propionic acid]; (c) was reduced by lowered day temperature; (d) was terminated by senescence and bleaching.

A Shubata soil was modified by the addition of organic matter or montmorillonite clay. Three annual applications of fluometuron [1,1-dimethyl-3-(α,α,α-trifluro-m-tolyl)urea], prometryne [2,4-bis(isopropylamino)-6-(methylthio)-s-triazine], and trifluralin (α,α,α-trifluro-2,6-dinitro-N,N-dipropyl-p-toluidine) were made and soil samples analyzed at the end of the third year. Less than 0.05 ppm prometryne was found in the subsoils. Prometryne present (by chemical analysis) in the surface soils ranged from 2% (of that originally applied) in the soil without additives to 20% in the soils modified with organic matter and clay. Approximately 12% of the prometryne present in the soil modified with organic matter and 32% of that in the soil modified with clay was detectable by bioassay. Trifluralin concentration (by chemical analysis) ranged from 2% in the soil without additives and soil modified with clay to 11% in the soil modified with organic matter. Approximately 100% of the trifluralin in soil without additives and soil modified with clay was detectable by bioassay while only 15% of that present in soil modified with organic matter was biologically detectable. Fluometuron was presented in the soils in amounts ranging from 0.6 to 1.9% of that applied. Prometryne and fluometuron greatly decreased the large crabgrass [Digitaria sanguinalis (L.) Scop.] population and increased the population of yellow nutsedge (Cyperus esculentus L.) and crowfootgrass [Dactyloctenium aegyptium (L.) Richter]. Trifluralin greatly decreased large crabgrass and crowfootgrass populations, but the plots became completely infested with yellow nutsedge. Horseweed [Conyza canadensis (L.) Cronq.] became the overall dominant species the first year after the field was taken out of production. Yellow nutsedge, bermudagrass [Cynodon dactylon (L.) Pers.], and other grasses were also prevalent.

A method is described in which tissue excised from cotyledons of 10-day-old pumpkin (Cucurbita pepo L. ‘Alabama Gold’) seedlings is floated in the light on a phosphate-based medium suspected of containing a photosynthesis inhibitor. The discs sink in a few hours if photosynthesis is inhibited; otherwise they continue to float. The method is capable of detecting a 0.002 to 0.02 ppm concentration of the herbicide prometryne [2,4-bis(isopropylamino)-6-(methylthio)-s-triazine]. The method could be used both for screening chemicals for potential herbicide use and for monitoring water for pollution by photosynthesis inhibitors.

Differences in emergence, height, and leaf number between corn (Zea mays L.), soybean [Glycine max (L.) Merr.] and seven dicotyledonous weed species were measured until plants reached 15 cm in height or for 40 days, whichever occurred first, under several temperature regimes. Corn grew faster than the weeds at all temperatures. Initially soybean grew more rapidly than the weeds, but when they reached 15 cm in height the growth rate of weeds exceeded that of soybean. A positive and highly significant curvilinear relationship between plant height and leaf number was obtained for several temperature regimes for each species. Equations were derived for determining leaf number from plant height for each species.

Four experiments were conducted to develop controls for downy brome (Bromus tectorum L.) in winter wheat (Triticum aestivum L. ‘Gaines’). In three experiments downy brome was removed at monthly intervals from emergence to harvest. In the third and fourth experiments, hand weeded and weedy controls were compared to chemical control with R11913 (3′-hydroxypropionanilide isopropylcarbamate). Downy brome, which emerged with wheat, was most competitive during March of each year. For maximum effectiveness, R11913 should be applied when downy brome has less than one to three tillers or chemical control will be erratic. On a silt loam soil with an average annual precipitation of 42 cm, downy brome densities of 108 to 160 plants/m2 lowered wheat yields 6% when competition was eliminated by March. When competition was permitted until wheat harvest (July), yield was reduced 40%.

The translocation of 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] and 2,4-D [(2,4-dichlorophenoxy) acetic acid] in bean (Phaseolus vulgaris L. ‘Stringless Greenpod’) seedlings was studied. 14C-labeled herbicides in amounts of 0.75 to μg were injected into the center of the stem at the cotyledonary node with a 1-μL syringe pipette. The effects of time and duration of treatment, herbicide concentration, and herbicide interaction on acropetal and basipetal translocation subsequent to treatment were determined. There was considerable basipetal as well as acropetal translocation of herbicide from the site of injection. Acropetal translocation of 2,4,5-T to primary leaves was very rapid until 2 hr after treatment, and during the following hours of treatment the 14C disappeared from the primary leaves. Acropetal translocation of 2,4,5-T to the young shoots was slow but continuous up to 6 hr after treatment, did not decrease during the latter hours of treatment, and was enhanced by high 2,4,5-T treatment levels. Translocation of 2,4,5-T to the nutrient solution continued for at least 72 hr after treatment while the roots accumulated maximum amounts in 6 to 12 hr. High treatment levels of 2,4,5-T enhanced the translocation of 2,4-D in the young shoots. However, 2,4-D did not promote the translocation of 2,4,5-T. Considerable variation occurred in the total translocation of 2,4,5-T when treatments were made at various times during the day. Translocation rates to the nutrient solution were at a maximum at about 12 A.M. and 12 P.M. each day regardless of the time of application of the 2,4,5-T.

Studies were conducted to determine both the extent and relative strengths of adsorption of twelve dinitroaniline herbicides to a Piano silt loam soil. The effects of soil on the growth of foxtail millet [Setaria italica (L.) Beauv.] in vitro on agar media containing 1.0 and 0.1-μM concentrations of the various herbicides and on the relative phytotoxicities of herbicide vapors arising from the agar media to the same species were also measured. Although considerable differences in the extents and strengths of adsorption of the respective herbicides to soil were noted, correlations with herbicide performance under field conditions were low. Extrapolation of laboratory results to a Piano silt loam soil under field conditions suggests that field applications of 0.32 kg/ha of the respective herbicides might result in herbicide concentrations between 0.00062 and 0.026 ppmw in the soil solution. These concentrations appeared to be less than those necessary to produce substantial plant injury from most of the dinitroaniline herbicides. High correlations between the effects of herbicide vapors on growth of the foxtail millet under laboratory conditions and the relative effectiveness of seven of the herbicides under field conditions suggest that absorption of vapors of the dinitroaniline herbicides by plants may be more important than absorption of the herbicides from soil solutions.

Cacodylic acid (hydroxydimethylarsine oxide) and MSMA (monosodium methanearsonate) gave slightly-visible inhibition of bacterial growth in pure culture at 1000 mg/L arsenic and moderate inhibition at 10,000 mg/L arsenic. There were no effects at 100 mg/L arsenic. Carbon dioxide evolution from three kinds of forest floor declined with increasing concentrations of MSMA and cacodylic acid. Increasing concentrations of MSMA caused an increase in carbon dioxide evolution from soil but cacodylic acid had no effect. Concentrations less than 10 mg/kg arsenic forest floor including L, F, and H horizons, or soil had no pronounced effect on organic matter decomposition.

Soybeans [Glycine max (L.) Merr.] planted conventionally or no-tillage tolerated approximately four times the recommended preemergence rates of linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] depending on the type planter used. Least injury to high rates of linuron was with a planter that placed seed slightly below the level of the surface of the field with a slightly rounded ridge of soil over the row. A planter leaving the seed under a slight furrow resulted in intermediate crop injury and a planter which deposited seed under a furrow 5 to 10 cm deep resulted in greatest crop injury. There was no consistent trend in the tolerance to linuron of soybeans planted conventionally or planted without tillage in small grain stubble with the straw removed. Row profile and its relation to seed placement was important in the tolerance of soybeans to linuron.

Fixation of 14CO2 in corn (Zea mays L. ‘VPI 646’ or ‘VPI648′) and transpiration in corn and soybean [Glycine max (L.) Mere. ‘Lee’] following treatment with atrazine [2-chloro-4-(ethylamino)-6-isopropylamine-s-triazine] were reduced by the addition of phytobland petroleum oils to the treatment solutions. Inhibition of 14CO2 fixation increased with increasing rates of oil and (or) atrazine and decreased with time following treatment. Oil type (naphthenic versus paraffinic) and viscosity (70, 100, 150, and 200 sec) did not significantly affect 14CO2 fixation or transpiration; however, when applied alone or in combination with atrazine, the 100-sec viscosity oils tended to be the most inhibitory.

EPTC (S-ethyl dipropylthiocarbamate) was applied to sand traps to evaluate weed control and the prevention of bermudagrass (Cynodon dactylon (L.) Pers.) encroachment. EPTC applied at 6.7 kg/ha in each of two applications at 6 to 7-week intervals, controlled an average of 88% common bermudagrass and 99% large crabgrass [Digitaria sanguinalis (L.) Scop.]. Although EPTC prevented bermudagrass from spreading into sand traps, the treatments did not cause permanent injury when applied directly to several bermudagrass varieties.

The reduction and assimilation of nitrate ions by 14-day old tall morningglory [Ipomoea purpurea (L.) Roth] seedlings were studied by monitoring the leaf nitrate, protein, and activity of the enzyme nitrate reductase (NADH: nitrate oxidoreductase, EC 1.6.6.1). The pH's of the grinding and assay mixtures yielding maximum nitrate reductase activity were determined to be 8.8 and 7.5 to 7.7, respectively. The maximum assay time for a linear reaction rate for nitrate reductase was estimated at 10 minutes. Decay rates of the enzyme preparations indicated a half-life of 30 min. Requirements for a cofactor to support the reaction were met with the addition of NADH (1 × 10−3 M final concentration) to the assay mixture. NADPH was not effective in supporting nitrate reductase activity. Inclusion of cysteine (1 × 10−2 M) in the grinding medium was necessary to insure maximum activity of the enzyme preparations. Both light and nitrate were required for nitrate reductase activity in morningglory leaves. Nitrate accumulated in leaf tissue in proportion to the concentration of nitrate in the nutrient medium. Above 7,530 lux luminescence, enzyme activity and tissue protein were related to the light intensity and the availability of nitrate in the nutrient medium on which the plants were grown.

I would start with a text from Bacon's New Atlantis that reads: “Men ought to know that in the theatre of human life it is only for gods and angels to be spectators.” We are at a stage of societal evolution where we must be part of the action. And action there is today – by politicians, by regulatory agencies, by industry, by scientists, by educators, and by the general public. Our basic challenge is to become a meaningful part of the action mechanism. And we are not alone among scientists trying to find our way in a very concerned and a very confused world. Science itself is suspect today.

Selected paraffinic and naphthenic phytobland oils used as adjuvants markedly enhanced the foliar uptake and acropetal translocation of ring-labeled atrazine [2-chloro-4-(ethylamino)-6-isopropylamino-s-triazine] by corn (Zea mays L. ‘VPI 646′), when compared with atrazine-14 C applied with nonionic polysorbate surfactant or in aqueous 25% methanol alone. Generally, 14C uptake increased with increasing concentration (1.25 to 20.0%) of a 100-sec viscosity paraffinic oil and with time (up to 32 hr) after application. No consistent additional promotion of atrazine-14 C uptake was derived from the use of emulsifier concentrations above 2.0% in the oil of a 10% oil-in-water emulsion. With a few exceptions, paraffinic and naphthenic oils of comparable viscosities were about equally effective as penetrant aids for atrazine. For both the paraffinic and naphthenic series, the 100-sec viscosity oils appeared to be slightly better penetrant aids than comparable 70, 150, and 200-sec oils.

In a 3-year study propanil (3′,4′-dichloropropionanilide) at 6.7 or 9.0 kg/ha was applied postemergence as single or split applications to rice (Oryza sativa L. ‘Starbonnet’ and ‘Nova 66′) 15 to 75 days after crop emergence. The effect on crop injury, maturity, grain yield, and seed and milling quality was measured on rice grown in weed-free plots. Residues of DCA (3,4-dichloroaniline) in grain and straw from treated rice plants and of propanil and TCAB (3,3′,4,4′-tetrachloroazobenzene) in treated soil were determined. Propanil applied at all times and rates in 1968 and 1970 or applied at all rates at 15 to 55 days after crop emergence in 1969 did not reduce grain yields, but 6.7 kg/ha applied 65 and 75 days after crop emergence in 1969 injured rice plants vegetatively and reduced grain yields. Plant maturity, seed viability and milling quality of grain were not affected. Residues of DCA in grain and straw were highest from treatments applied 65 and 75 days after crop emergence; rice straw contained more DCA than did grain.