Studies determined the effect of sodium bisulfate (NaHSO4) on the phytotoxicity, retention, uptake, and translocation of the suspension concentrate formulation of imazamethabenz in wild oats. NaHSO4 completely solubilized this herbicide formulation when added in an equimolar concentration and did not affect herbicidal activity at NaHSO4 concentrations below 28 mM when used in a carrier volume of 100 L ha−1. NaHSO4 improved phytotoxicity at a carrier volume of 33 L ha−1. NaHSO4 at 28 mM increased the efficacy of imazamethabenz applied as individual drops on growth chamber-grown wild oats. The herbicide retention was not changed but foliar absorption and acropetal translocation were increased, while basipetal translocation was decreased. The increase in phytotoxicity of imazamethabenz with NaHSO4 was related to absorption of imazamethabenz by the target plants.

A compact incorporator-planter, which incorporates herbicides into moist soil simultaneously with planting of cotton (Gossypium hirsutum L.), was constructed and evaluated over 3 yr using six herbicides. Weed control was consistent with that reported for large, cumbersome units utilizing standard planters and incorporating units from ground-driven rotary tillers and was enhanced in seasons in which rain fell during the first 3 weeks after planting. Among the dinitroaniline herbicides, dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) controlled barnyardgrass [Echinochloa crus-galli (L.) Beauv.], and redroot pigweed (Amaranthus retroflexus L.) most effectively. Cotton stands and yields were equivalent to those obtained using standard cotton-planting methods.

Inhibition of seedling growth and four assays for inhibition of photosynthesis were used to compare karbutilate [tert-butylcarbamic acid ester with 3-(m-hydroxyphenyl)-1,1-dimethylurea] with derivatives of karbutilate in which either the urea or carbamate side chain was missing. Karbutilate was a more potent, more presistent, and more specific inhibitor of photosynthesis than the phenylurea derivative fenuron (1,1-dimethyl-3-phenylurea) that would be formed by removal of the carbamate side chain. However, karbutilate did not exert the growth-inhibiting action observed for the alkyl carbamate derivative phenyl-N-tert-butylcarbamate, formed by removal of the urea side chain, which does not affect photosynthesis at concentrations below 10-3 M.

Heights of corn and giant foxtail (Setaria faberii Hermm.) were measured during 1963, 1964, and 1965 in east-central Illinois to establish guidelines for postemergence control of this weed in corn. With an average planting date of May 9, corn grew to a height of 6 in and foxtail 2 in by May 28. With corn growing at a daily rate of 1 in and foxtail ½ in from June 5 to 20, foxtail height was 40 to 45% that of corn.

Field trials were conducted from 1991 to 1993 in the northern cotton-producing area of Alabama to evaluate the interaction of various production inputs for pest management and cotton development, maturity, and yield. Two levels of tillage (conventional and no-till), herbicide (1.12 and 2.24 kg ai ha−1 fluometuron, preemergence, with post-directed herbicides), insecticide (0.5 and 0.85 kg ai ha−1 aldicarb, in-furrow), and fungicide (0.9 kg ai ha−1 quintozene plus ethridazole, in-furrow or 0.14 kg ai ha−1 metalaxyl, hopper-box) programs were evaluated. The inputs investigated did not interact significantly to change the overall production strategy. Prickly sida required a higher level of herbicide input than did the entireleaf/ivyleaf morningglory complex. Both species were sufficiently controlled using reduced levels of fluometuron without sacrificing yield; however, cultivation was necessary in conventional tillage treatments to maintain control. A postemergence-directed herbicide treatment was also necessary for weed control, regardless of tillage. Decreasing the levels of each input simultaneously did not interact to affect cotton stand, height, early-season thrips counts, cotton maturity, or yield. Cotton was shorter in no-till than conventional plots.

The absorption and distribution of 14C terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] and 14C-fluometuron [1,1-dimethyl-3-(α,α,α-trifluoro-m-tolyl)urea] in cotton (Gossypium hirsutum L. ‘SJ-1’) and snapbean (Phaseolus vulgaris L. ‘Tenderette’) seeds during germination was studied. Seeds of the susceptible snapbean absorbed larger amounts of both herbicides from soil than the resistant cotton seeds. The herbicides accumulated mainly in the seed coat of cotton which shed following emergence, with no translocation to the seedling leaves. In snapbean seeds the herbicides accumulated in the cotyledons, which served as a source for acropetal flow to the developing foliage of the young seedling.

Growth and percentage survival was measured for slash pine (Pinus elliottii Engelm.), shortleaf pine (P. echinata Mill.), Virginia pine (P. virginiana Mill.), and loblolly pine (P. taeda L.) seedlings treated with: (a) 0.07 to 4.48 kg/ha 2,6-dichlorobenzonitrile (dichlobenil), (b) 0.28 to 8.96 kg/ha 1,1-dimethyl-3-(a,a,a-trifluoro-m-tolyl)urea (fluometuron), or (c) 1.12 to 8.96 kg/ha S-propyl butylethylthiocarbamate (pebulate). Herbicide toxicity to pine seedlings was in order of dichlobenil > fluometuron > pebulate. Acceptance of mild growth reduction would permit pebulate utilization in seed bed nurseries.

Plants of curly dock (Rumex crispus L.) were subjected to soil temperatures of 10, 15, 26, and 35 C in a growth chamber. A soil temperature of 10 C was most favorable for root growth and production of large seeds. The highest yields of seeds and fruit were obtained at 26 C. Significant reductions in seed and fruit production, wt per 100 seeds, plant height, and growth rate occurred at 35 C. The total germination of mature seeds was not affected by soil temperature, but the seeds ripened at 26 and 35 C germinated faster than those from the 10 and 15 C treatments.

New Line Early Perfection peas (Pisum sativum L.) in the 10th-node stage were treated with a foliar broadcast application of 1 lb/A of the sodium salt of carboxyl carbon-14 labeled 4-(2-methyl-4-chlorophenoxy) butyric acid (MCPB*). Direct counting of C14 indicated that MCPB* equivalent to 8.4 ppm on the fresh weight basis was in or on the pea tissue immediately after treatment. The concentration declined rapidly for 6 days following treatment and then at a reduced rate until shelled pea harvest 5 weeks later. Translocation of C14 was studied by autoradiography. Most of the labeled material was retained at the application site. Very little was translocated to the new growth or into the pea seed. The plants retained C14 equivalent to 0.4 ppm MCPB* at the time of harvest with a concentration in the shelled peas of not more than 0.1 ppm.

Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} at 2 or 4 ppmw placed 0 to 3, 8 to 11, or 15 to 18 cm deep in soil columns reduced root and shoot weights of buffelgrass [Pennisetum ciliare (L.) Link # PESCI] 30 days after emergence. Plains bristlegrass (Setaria macrostachya H.B.K.) seedling shoot weights were not reduced when 2 ppmw tebuthiuron was placed 8 to 11 cm deep or deeper. Effects of tebuthiuron at 0.13 to 0.50 ppmw on buffelgrass shoot and net tiller production were not moderated by the presence of honey mesquite (Prosopis glandulosa # PRCJG) in the pots. However, regardless of tebuthiuron dosage, average height and shoot weight of buffelgrass seedlings were greater when seedlings were grown in soil collected from beneath honey mesquite canopies compared to growth in soil from interspaces. Therefore, spatial variations in buffelgrass response to applications of tebuthiuron for control of invading shrubs may largely be attributed to soil changes induced by woody plants rather than to presence of shrubs.

Pygmyflower is becoming increasingly abundant in conservation-tillage cropping systems of the Canadian Prairies. Increased knowledge of pygmyflower biology would facilitate development of integrated programs for its control. A controlled environment study was conducted to determine the combined effect of various soil temperature and soil water levels on pygmyflower emergence. Pygmyflower emerged at soil temperatures ranging from 10 to 25 C with optimal emergence at 15 C. Emergence was inhibited completely at 5 or 30 C. Pygmyflower emergence markedly declined as soil water content decreased. At progressively lower soil water levels of − 0.03, − 0.28, − 0.53, − 0.78, − 1.03, and − 1.53 MPa, pygmyflower emergence at 15 C was 71, 50, 49, 29, 24, and 15%, respectively. The interaction of warm and dry soils caused the greatest inhibition of pygmyflower emergence. Rate of pygmyflower emergence was reduced greatly by either lowering soil temperature or reducing soil water content. A decrease in soil temperature from 25 to 10 C increased the time to reach 50% emergence (ET50) by 9 to 14 d, whereas a decrease in soil water content from − 0.03 to − 1.53 MPa increased ET50 by 7 to 16 d. Results suggest that pygmyflower may pose the greatest problem in winter crops or early-planted spring crops. Information gained in this study will contribute to the development of an improved pygmyflower management program in annual cropping systems.

The major reserve lipid of yellow foxtail [Setaria lutescens (Weigel) Hubb.] caryopses is triacylglyceride stored in lipid bodies. Lipid bodies are heavily concentrated in the cells of the embryo axis, scutellum, and aleurone layer and are roughly spherical (average diam 0.5 μm). Percentage lipid (hot isopropanol extract) on a fresh-weight basis of mature, unimbibed seed and caryopses collected locally was about 6.4 and 11%, respectively. About 95% of the total (0.23 mg/caryopsis) was saponifiable and distributed among fatty acid classes as follows: 16:0, 5.8%; 18:0, 1.5%; 18:1, 16.2%; 18:2, 73.7%; and 18:3, 2.8%. In nondormant caryopses, saponifiable lipid content declined (18:1 and 18:2 only) about 23% during the first 6 days after imbibition in the dark at 25 C. This modest decline was preceded by the appearance of an alkaline lipase at about 24 h after the onset of imbibition. Free fatty acids accumulated during these early stages of germination and accounted for about 22% of the total saponifiable lipid remaining (0.17 mg/caryopsis) 6 days after the onset of imbibition. Lipid content and lipase activity did not change in dormant caryopses treated similarly. The delayed initiation of lipid mobilization in germinating caryopses suggests that triacylglyceride degradation is not a pivotal metabolic pathway controlling dormancy.

Roots of 10- and 14-day-old seedlings and excised leaves of cotton (Gossypium hirsutum L. ‘Coker 310’), jimsonweed (Datura stramonium L.), peanuts (Arachis hypogaea L. ‘Florigiant’), and prickly sida (Sida spinosa L.) were treated with ring-labeled 14C-tetrafluron {N,N-dimethyl-N′-[3-(1,1,2,2-tetrafluoroethoxy)phenyl] urea} in liquid culture. Herbicide absorption and subsequent translocation were limited in peanuts, intermediate in cotton, and very high in jimsonweed and prickly sida. Absorption of 14C-tetrafluron increased with time in 10- and 14-day-old seedlings. After 6 h, 10-day-old jimsonweed had absorbed as much as 50% of the initial 10-μg dose, whereas peanuts absorbed only 10%. Almost 100% uptake was observed after 48 h with 14-day-old seedlings of jimsonweed and prickly sida. Methanol-extracted 14C increased with time, and was higher for the weeds than for the crops. Only a small fraction of methanol-insoluble radioactive material was obtained, with the largest value in 14-day-old cotton at 48 h (3.0%). Autoradiographs demonstrated more rapid translocation of radioactivity from roots to shoots in jimsonweed and prickly sida than in cotton and peanuts. Limited absorption and translocation of tetrafluron in seedlings of peanut and cotton, and the rapid absorption and subsequent accumulation of high concentrations in seedlings of jimsonweed and prickly sida, are proposed to explain the selective action observed.

Weed-control evaluations in ratoon-cropped grain sorghum [Sorghum bicolor (L.) Moench.] indicated that acceptable broadleaf weed control (>80%) in the second crop could be achieved by the use of a contact herbicide plus a residual herbicide applied after first harvest. Annual grasses, especially volunteer grain sorghum, were controlled in the second crop with metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] plus propazine [2-chloro-4,6-bis(isopropylamino)-s-triazine] applied preemergence at planting and followed by metolachlor, cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile}, or pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] applied after first harvest. Second-crop grain yields were not adversely affected by any treatments, and it appeared that satisfactory weed control in the first crop lessened the need for a residual herbicide in the second crop.

Polymerized and conventional (2,4-dichlorophenoxy)-acetic acid (2,4-D), (2,4,5-trichlorophenoxy)acetic acid (2,4,5-T), 3,6-dichloro-o-anisic acid (dicamba), and 4-amino-3,5,6-trichloro-picolinic acid (picloram) were applied alone and in certain combinations to several brush species. Generally there were no significant differences in effectiveness between conventional and polymerized herbicides on honey mesquite (Prosopis juliflora (Swartz) DC. var. glandulosa (Torr.) Cockrell), huisache (Acacia farnesiana L. Willd.), Macartney rose (Rosa bracteata Wendl.), live oak (Quercus virginiana Mill.), whitebrush (Aloysia lycioides Cham.), and winged elm (Ulmus alata Michx.). Conventional granular picloram was more effective on yaupon (Ilex vomitoria Ait.) than polymerized formulations.