Johnsongrass [Sorghum halepense (L.) Pers.] and soybeans [Glycine max (L.) Merr. ‘Lee 68’] were treated over-the-top with glyphosate [N-(phosphonomethyl)glycine] at 0.2 and 0.4 kg/ha with surfactant in spray solutions and 0.4 and 0.7 kg/ha without surfactant in spray solutions. Treated plants were maintained in the growth chamber for 2 weeks after treatment at 24, 29, and 35 C; 45 and 100% relative humidity (RH); and 12 and 20% soil moisture. Glyphosate at 0.4 kg/ha applied without surfactant controlled johnsongrass better at 100% than at 45% RH. Johnsongrass control was better with 20% than with 12% soil moisture. Averaged over all evironments, the order of glyphosate toxicity to johnsongrass at 0.4 and 0.7 kg/ha was 35 C > 29 C > 24 C. The environmental condition of 45% RH and 12% soil, moisture resulted in least johnsongrass control regardless of temperature. The order of glyphosate toxicity to soybeans when applied without surfactant was 24 C > 29 C > 35 C. Glyphosate applied without surfactant was more toxic to soybeans at 100% than at 45% RH and more toxic at 12% than at 20% soil moisture. Surfactant in spray solutions increased glyphosate toxicity to johnsongrass and soybeans.

Nine substituted dinitronaline herbicides were studied to determine their effectiveness in controlling common root rot of peas (Pisum sativum L.) caused by Aphanomyces euteiches Drechs. under field conditions. Most of the dinitroaniline herbicide treatments increased plant stand, plant fresh weight, and shelled pea yield due to root rot suppression in each of the three years studied. Weed control was good in all plots and did not contribute to yield differences. Root rot suppression and crop injury were the primary determinants of yields. The greatest yield increases when compared with the weeded control were 82% for 0.56 kg/ha of dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) in 1974, 80% for 0.84 kg/ha of fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl) aniline] in 1975, and 26% for 1.68 kg/ha of pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] in 1976. The best average yield increases over all years were 54% for the combination of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) and oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) at 0.56 + 0.56 kg/ha, 49% for fluchloralin at 0.84 kg/ha, and 43% for pendimethalin at 0.84 kg/ha. Annual applications of 0.84 kg/ha of trifluralin delayed the rate of pathogen infestation of a field repeatedly planted to peas.

Yellow nutsedge (Cyperus esculentus L.) and purple nutsedge (C. rotundus L.) were grown in clay pots in the field to investigate the effect of sunlight intensity, planting date, and harvesting date on growth and development. Reducing the length of the growing season by delayed planting or early harvesting reduced the growth (dry matter accumulation) and tuber production of both species. Purple nutsedge growth (dry matter accumulation) was linearly reduced at 30 and 73% shade, but yellow nutsedge growth at 30% shade was not different from that at full sunlight. Tuber production in both species began about August 1, with slight delays in the initiation of tuber growth as planting date was delayed. At the end of the growing season a significant number of tubers were formed in both species even at the latest planting date under 73% shade.

A comparative scanning electron microscopy (SEM) study was performed on the surfaces of seeds and coleoptiles of several conspecific rice (Oryza sativa L.) varieties including the weed red rice and several cultivars: Mochi-Gommi and LA-110 (medium grained); Starbonnet, Labelle, and Bluebelle (long grained). Seed surfaces of red rice, LA-110 and Mochi-Gommi possessed trichomes that were more numerous at the seed apex than on other seed parts. Red rice also exhibited a large central awn extending from the seed apex. This awn had spines along its axis and numerous spines at its apical end. These characteristics were absent in the other varieties. No significant differences were noted in the seed-surface tubercles and in the quantity or structure of wax on the seed surface in all six samples. The coleoptiles of all samples had several similarities: the stomata were arranged in parallel rows on both the adaxial and abaxial surfaces, the epicuticular wax structure on both surfaces was rodlet, prickle hairs were found on the adaxial coleoptile surface (but absent on abaxial), spines were present on the edge of the apical end (older portion) and decreased in number toward the basal end (younger portion), and two types of papillae (based on size and shape) were present on both the adaxial and abaxial surfaces. Although there were varietal differences among developing coleoptiles on a macroscopic scale, significant morphological differences were not discernible at the SEM level.

In field experiments during 1975 to 1977 the final yield of cucumbers (Cucumis sativus L. ‘Salty’) was unaffected when a naturally occurring weed infestation remained in the plots for the first 12 days after emergence in 1975 and for the first 24 days in 1976 and 1977, provided the crop was kept weed-free subsequently. If the cucumbers were kept weed-free for the first 12 days after emergence in 1975, 24 days after emergence in 1976, and 36 days after emergence in 1977, there was no loss of yield caused by weeds that emerged later in the season. The critical period of weed interference was therefore between 12 and 36 days after crop emergence. In other experiments, cucumber yields were reduced significantly when only 5% of the weeds were allowed to remain in the plots longer than 24 days after crop emergence. The percentage of various commercial grades, based on cucumber size, was not altered by weed interference and appeared to be dependent on harvesting frequency.

The herbicide 2,4-D [(2,4-dichlorophenoxy)acetic acid] was applied as sublethal rates to sugarbeets (Beta vulgaris L. ‘Mono Hy D2’) in the field at different growth stages to determine its effect on growth and yield. The greatest reduction in top growth occurred when the highest rate of 2,4-D, 0.07 kg/ha, was applied to the oldest plants (12-leaf stage). All rates of 2,4-D reduced the components of sucrose yield (percentage sucrose, percentage purity, and root weight) to the extent that, together, the three components contributed to a significant reduction in recoverable sucrose. The yields of recoverable sucrose were reduced 6.8, 7.8, and 13.2% by the 0.017, 0.035, and 0.07 kg/ha rates, respectively.

Seed of yellow foxtail (Setaria lutescens (Weigel) Hubb.) biotypes collected in Connecticut, Iowa, Massachusetts, Pennsylvania, and California were grown under field conditions at Davis and Woodland, California. Three biotypes collected in California alfalfa (Medicago sativa L.) fields all exhibited only a prostrate growth habit; the biotypes from the eastern United States all had an upright growth habit. The California biotypes were always glaucous; those collected in the east were not glaucous. Ratio of culm height to culm length were near unity for the eastern biotypes but averaged 1.5 to 1.7 for the California biotypes. Variations existed between biotypes in days from planting to heading, number of nodes per culm, leaf shape and size, and in final dry weight per plant.

At Hilario Ascasubi, Argentina, and Prosser, Washington, EPTC (S-ethyl dipropylthiocarbamate) was injected in sandy soil as two lines 5 cm deep and 6 cm apart. At 2 kg/ha (assuming the treated area was 12 cm wide), EPTC controlled 95 to 100% of foxtail millet [Setaria italica (L.) Beauv.] in a band 13 to 14 cm wide without significant injury to alfalfa (Medicago sativa L.) seeded 1.5 cm deep midway between the two lines of herbicide. At 3 and 4 kg/ha, EPTC sometimes injured alfalfa, but only temporarily, and at 1 kg/ha, it controlled 75 to 100% of the millet in a band 11 to 12 cm wide. Where alfalfa is seeded in rows, especially for seed production, subsurface line injection of EPTC could provide effective, efficient, and economical selective control of certain annual weeds.

A collection of common purslane (Portulaca oleracea L.) ecotypes from various locations around the world was assembled at the University of Illinois. Applications of nitrofen (2,4-dichlorophenyl-p-nitrophenyl ether) to the various ecotypes showed that 3 of the 26 ecotypes [India, Mexico, and Florida (Sanford)] exhibited some degree of tolerance. This marginal tolerance rapidly disappeared as the rate of nitrofen increased beyond 0.56 kg/ha. All of the ecotypes tested were susceptible to applications of oxyfluorfen [2-chloro-2-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. Oxyfluorfen was toxic to common purslane plants at rates as low as 5 g/ha. Treatment of ‘Hybelle’ (tolerant) and ‘Rio Verde’ (susceptible) cabbage (Brassica olerace var. capitata L.) cultivars with 3.36 kg/ha nitrofen reduced plant fresh weight to 82% and 62%, respectively, of control. Oxyfluorfen at 0.15 kg/ha reduced fresh weight to 60% and 27% for Hybelle and Rio Verde, respectively. Applications of nitrofen at 3.36 kg/ha reduced plant fresh weight in Hybelle the same amount as 100 g/ha oxyfluorfen and 70 g/ha in Rio Verde.

The uptake, distribution, and metabolism of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] by sugarcane (Saccharum officinarum L.) cultivars ‘PR980’ and ‘PR1048’ were determined 3 and 10 days after root treatment with 18.4 μM 14C-ring-labeled diuron. Uptake and distribution did not account for the differential tolerance of the two cultivars to diuron. Concentration of unmetabolized diuron was higher in the shoot and root of susceptible cultivar PR1048 than in tolerant cultivar PR980 at 3 and 10 days after treatment. The predominant metabolic pathway for diuron metabolism in both susceptible and tolerant sugarcane cultivars appeared to be the formation of mono-methyl diuron and its conjugation. The metabolic process was more rapid in PR980 than PR1048, apparently accounting for the tolerance of PR980.

The effect of calcium and nitrogen level on the uptake of linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] from nutrient solution by soybean [Glycine max (L.) Merr.] seedlings was determined and related to root membrane fatty acid composition. Calcium levels in the nutrient solution were 0.4, 4.0, or 8.0 mM and nitrogen levels were 4.0, 16.0, or 32.0 mM with the pH adjusted to 6.5. As calcium concentration increased, linuron uptake decreased. The reverse was true for nitrogen. These changes were not related to transpiration. Increasing calcium concentration increased palmitic acid and decreased linolenic acid in the plasmalemma of the soybean roots resulting in a greater degree of saturation. Nitrogen likewise increased the degree of saturation in the plasmalemma, but the effect was mainly seen in the balance between stearic and linoleic acids. In the mitochondria, however, the trends were inconclusive. High levels of linolenic acid were observed in the mitochondria regardless of treatment.

Two applications of benefin (N-butyl-N-ethyl-α,α,α,-trifluoro-2,6-dinitro-p-toluidine), profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], prosulfalin N-[[4-(dipropylamino)-3,5-dinitrophenyl]sulfonyl]-S,S-dimethylsulfilimine, and napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] provided full-season large crabgrass [Digitaria sanguinalis (L.) Scop.] control in turfgrass. Benefin was applied at 3.3 kg/ha in March and 2.2 kg/ha in May while other herbicides were applied at 2.2 kg/ha in March and May. Satisfactory goosegrass [Eleusine indica (L.) Gaertn.] control was obtained with a single March treatment with prosulfalin, but two applications of napropamide in March and May were required for similar control. None of the herbicide treatments severely injured common bermudagrass [Cynodon dactylon (L.) Pers.] or Kentucky bluegrass [Poa pratensis (L.) ‘Common’] in these studies. Prosulfalin at 6.6 kg/ha applied as single treatment or 3.3 kg/ha in each of two applications resulted in moderate injury to Kentucky bluegrass in 1 of 2 yr.

The antidote R-25788 (N,N-diallyl-2,2-dichloroacetamide) protected corn (Zea mays L. ‘DeKalb 315A’) seedlings from injury caused by the acetanilide herbicides, alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide], metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide], H-22234 [N-chloroacetyl-N-(2,6-diethylphenyl)glycine ethyl ester], and H-26910 [N-chloroacetyl-N-(2-methyl-6-ethylphenyl)glycine isopropyl ester] in a greenhouse study. R-25788, however, did not protect four weed species tested. R-25788 only partially protected corn from injury caused by acetochlor [2-chloro-N-(ethoxymethyl)-6′-ethyl-o-acetotoluidide]. R-25788 was an effective antidote whether applied preemergence, preplant-incorporated, or as a tank mix. Injury symptoms caused by EPTC (S-ethyl dipropylthiocarbamate) and the acetanilide herbicides were similar; both caused leaf twisting and rolling, and at high rates leaves failed to emerge through the coleoptile.

Wettable powder and granular formulations of pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide], applied at 1.7 kg/ha to the soil surface or incorporated to depths of 1.3 to 7.5 cm, controlled dodder (Cuscuta indecora Choisy and C. campestris Yunck.) completely in the greenhouse for periods of 6 to 16 weeks. Seedlings emerged in pronamide-treated soil, but did not elongate normally and did not twine. Pronamide had very little activity as a vapor. In the field, the same rate applied to the soil surface and sprinkler irrigated or mechanically incorporated with the soil usually controlled dodder for about 1 month longer than did the standard herbicide, chlorpropham (isopropyl m-chlorocarbanilate) at 6.7 kg/ha. Pronamide at 6.7 kg/ha did not injure established alfalfa (Medicago sativa L.).

Control of field bindweed (Convolvulus arvensis L.) on irrigated land was studied by application of herbicides once in the fall and then only in the spring for the next 4 yr. Control of field bindweed 8 months after a fall application of 2.2 kg/ha of dicamba (3,6-dichloro-o-anisic acid) or 3.4 kg/ha of 2,4-D [(2,4-dichlorophenoxy)acetic acid] was 90 and 83%, respectively. Spring applications of 0.28 kg/ha of dicamba, 0.56 kg of 2,4-D, or the mixture of these two herbicides suppressed the growth of field bindweed similarly each year. By the fall of the fourth year, field bindweed covered an average of 9% of the soil surface in the plots that received both fall- and spring-applied herbicide treatments, 72% in plots that received only fall-applied herbicide treatments, and 80% in the untreated plots. Yield of corn (Zea mays L. ‘Pioneer 3306’) was significantly higher in all treated plots than in the untreated check plots in 1 out of 2 yr. Yield of sorghum [Sorghum bicolor (L.) Moench ‘Pioneer 833’] was not increased significantly in any treated plots, but in 1 yr the mixture of 0.28 kg/ha of dicamba plus 0.56 kg/ha of 2,4-D reduced yield significantly when this mixture was applied twice at these same rates in the spring.

Dark-incubated common purslane (Portulaca oleracea L.) seed synthesize very little protein and essentially no nucleic acids. Dark-incubated seed incorporate only 14 × 10−3 nmoles 14C-leucine/mg protein/12-h dark. In contrast, seed exposed to 12-h light following 24-h dark incubation incorporate 365 × 10−3-nmoles 14C-leucine/mg protein/12-h light. Once dormancy is broken by exposure of seed to light, initiation of radicle protrusion occurs at 12 h. Protein synthesis gradually increases with time in the light and precedes nucleic acid synthesis which is associated with radicle protrusion. During the 12-h lag period preceding radicle protrusion protein synthesis increases significantly by 3 to 9 h in light, RNA synthesis by 9 h in light, and DNA synthesis by 12 h in light. After 12 h in light, 32P can be detected in all nucleic acid fractions, DNA and RNAs.

Glyphosate [N-(phosphonomethyl)glycine] was separated from its potential metabolites, aminomethylphosphonic acid, glycine, and sarcosine by using 500 μm-thick cellulose plates developed with ethanol:water:15 N NH4OH:trichloroacetic acid (TCA):17 N acetic acid (55:35: 2.5:3.5 g:2, v/v/v/w/v with v in ml). This TLC system separated impurities from the 14C-glyphosate standard and glyphosate from possible metabolites in treated field bindweed (Convolvulus arvensis L.).

The carbon banding technique was evaluated for control of volunteer Kentucky bluegrass (Poa pratensis L.) while Kentucky bluegrass was established for seed production. At Madras, Oregon, where terbacil (3-tert-butyl-5-chloro-6-methyluracil), diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], and simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] were applied at several rates each, volunteer Kentucky bluegrass control between the carbon bands ranged from 80 to 99+%. At Corvallis, Oregon, where Colonial bentgrass (Agrostis tenuis Sibth. ‘Highland’), red fescue (Festuca rubra L. ‘Pennlawn’), perennial ryegrass (Lolium perenne L. ‘NK-100’), and orchardgrass (Dactylis glomerata L. ‘S-143’) were planted to allow identification of volunteer Kentucky bluegrass both between and in the carbon bands, diuron, atrazine, and a combination of diuron and terbacil eliminated volunteer Kentucky bluegrass. Terbacil did not control all Kentucky bluegrass between the bands. None of the herbicide treatments adversely affected crop establishment or seed yield.

Four starch-encapsulated formulations of EPTC (S-ethyl dipropylthiocarbamate) and of butylate (S-ethyl diisobutylthiocarbamate) were prepared and evaluated by comparison with their respective emulsifiable concentrate formulations for their slow-release capabilities and efficacies. Chemical and biological evaluation indicated that difference in controlled-release could be achieved by the selection of the starch xanthate and oxidant used in the formualtion process. EPTC and butylate released slower when formulated as starch-encapsulated granules than when formulated as emulsifiable concentrates under soil conditions that favored rapid release. The initial release was adequate for weed control and slow enough for desired residual activity. Repeated seeding and harvesting the treated soils and bioassays of treated soils generally produced release rate anticipated from short term dry and wet chemical tests.

14C-glyphosate [N-(phosphonomethyl)glycine] degradation to 14CO2 was examined in a Spinks sandy loam, Collamer silt loam, and a Norfolk loamy sand. After 32 days, 40, 9.5, and 3% of the 14C-glyphosate was recovered as 14CO2 in the three soils, respectively. The degradation was primarily microbial. Phosphate additions stimulated 14C-glyphosate degradation to a limited extent in the Collamer silt loam but not in the Norfolk loamy sand. Additions of Fe+++ and Al+++ ions reduced degradation in the Spinks sandy loam. It is postulated that formation of colloidal Fe and Al precipitates in modified soils with concomitant adsorption of 14C-glyphosate is responsible for decreased availability of 14C-glyphosate to microorganisms. Mn++ additions were found to increase degradation. Spinks soil and carbon substrate amendments failed to substantially increase degradation rates in both soils with low degradation rates.