Showing papers in "Weed Science in 1975"
TL;DR: Glyphosate [N-(phosphonomethyl)glycine] was readily bound to kaolinite, illite, and bentonite clay and to charcoal and muck but not to ethyl cellulose as mentioned in this paper.
Abstract: Glyphosate [N-(phosphonomethyl)glycine] was readily bound to kaolinite, illite, and bentonite clay and to charcoal and muck but not to ethyl cellulose. Fe+++ and Al+++-saturated clays and organic matter adsorbed more glyphosate than Na+ or Ca+-saturated clays and organic matter. Glyphosate appears to be bound to the soil through the phosphonic acid moiety as phosphate in the soil competed with 14C-glyphosate for adsorption sites. Glyphosate mobility in the soil was very limited and was affected by pH, phosphate level, and soil type. The 14C-glyphosate was biodegraded in soil to 14CO2 possibly by co-metabolism. Potentiometric titrations of the compound gave pKa values of 2, 2.6, 5.6, and 10.6.
444 citations
TL;DR: The respiration of quackgrass treated with glyphosate was significantly reduced 9 days after treatment, and Glyphosate reduced total photosynthesis more in quack Grass than in wheat.
Abstract: Radioactive glyphosate [N-(phosphonomethyl)glycine] is rapidly absorbed with a large portion of the 14C translocated to the rhizomes and untreated shoots of quackgrass [Agropyron repens (L.) Beauv.]. The adjuvant used with glyphosate was important in determining its phytotoxicity to quackgrass. In other perennial weeds and annual species, glyphosate also moved to the areas of highest metabolic activity. In Canada thistle [Cirsium arvense (L.) Scop.], bentazon (3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one 2,2-dioxide) at 2.24 kg/ha applied prior to treatment with 14C-glyphosate reduced 14C translocation. Iron or nitrilotriacetic acid (NTA) did not appear to effect glyphosate activity on wheat (Triticium aestivum L. ‘Avon’). The respiration of quackgrass treated with glyphosate was significantly reduced 9 days after treatment. Glyphosate reduced total photosynthesis more in quackgrass than in wheat.
240 citations
TL;DR: In greenhouse studies, soil applications of 14 C-methyl-labeled glyphosate were not readily absorbed by corn and soybean and glyphosate available to plants in sand culture was absorbed, suggesting initial inactivation of glyphosate in soil is by reversible adsorption to clay and organic matter through the phosphonic acid moiety.
Abstract: In greenhouse studies, soil applications of 14C-methyl-labeled glyphosate [N-(phosphonomethyl)glycine] were not readily absorbed by corn (Zea mays L. ‘Michigan 400’) and soybean [Glycine max (L.) Merr. ‘Hark’]. However, glyphosate available to plants in sand culture was absorbed. Wheat (Triticum aestivum L. ‘Avon’) a sensitive bioassay plant, was used to detect the herbicide. Clay loam and muck soil rapidly inactivated 56 kg/ha of glyphosate. Autoclaving of the soil did not prevent the inactivation of glyphosate. In a sandy clay loam soil, application of 56 kg/ha of glyphosate decreased plant growth with increasing pH. Additions of 98 or 196 kg/ha of phosphate to the soil surface decreased glyphosate inactivation in the soil. It is postulated that initial inactivation of glyphosate in soil is by reversible adsorption to clay and organic matter through the phosphonic acid moiety.
227 citations
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109 citations
TL;DR: In this paper, the seasonal variation in germinability of seed reserves in a degraded big sagebrush (Artemisia tridentata Nutt) community was investigated and a bioassay was employed to determine the seed viability.
Abstract: We investigated seasonal variation in germinability of seed reserves in a degraded big sagebrush (Artemisia tridentata Nutt.) community. A bioassay was employed to determine germinability. There were many more germinable seeds and seedling establishment was greater under the shrub canopies than in the interspace. Caryopses of downy brome (Bromus tectorum L.) were the most abundant of any species in the litter where most of the seeds were located. Seasonal germinability of downy brome caryopses depends on the environment of the seedbed when the samples were collected and on the incidence of environmentally-induced dormancy or on loss of dormancy.
78 citations
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67 citations
TL;DR: In this article, the authors reported that weed control practiced by water users along certain sections of S2.15W markedly reduced both the kind and number of weed seeds found in the water when compared with PL.15.LR on which no weed control measures were used.
Abstract: Irrigation laterals PL.15.LR and S2.15W, in the Yakima Valley of Washington and the Columbia River near Paterson, Washington, were sampled for weed seeds during 1970, 1971, and 1973–74, respectively. Weekly or biweekly screenings of the water in the three systems during the irrigation season yielded seeds of 137, 84, and 77 plant species, respectively. In the same order, the total number of seeds per 254 kl of water averaged 2,220, 682, and 292 for the season. Moreover, if the seeds were evenly distributed in the average amount of water used to irrigate the land during the season, the number of seeds disseminated would average 94,500, 10,400, and 14,100 per hectare. Weed control practiced by water users along certain sections of S2.15W markedly reduced both the kind and number of weed seeds found in the water when compared with PL.15.LR on which no weed control measures were used.
64 citations
TL;DR: Ten warm-season and six cool-season weed species were grown in the glasshouse on Hartsells fine sandy loam soil and Lucedale sandy loAM soil at pH levels from 4.7 to 6.3.
Abstract: Ten warm-season and six cool-season weed species were grown in the glasshouse on Hartsells fine sandy loam soil and Lucedale sandy loam soil at pH levels from 4.7 to 6.3. Growth of species varied widely in response to soil pH as measured by herbage yield. Showy crotalaria (Crotalaria spectabilis Roth), coffee senna (Cassia occidentalis L.), and large crabgrass (Digitaria sanguinalis (L.) Scop.] were highly tolerant to low pH soils. Sicklepod (Cassia obtusifolia L.), annual bluegrass (Poa annua L.), Carolina geranium (Geranium carolinianum L.), and buckhorn plantain (Plantago lanceolata L.), were medium to high in tolerance. Jimsonweed (Datura stramonium L.), tall morningglory [Ipomoea purpurea (L.) Roth], crowfootgrass [Dactyloctenium aegyptium (L.) Richter], and prickly sida (Sida spinosa L.) were medium to low in tolerance to low soil pH. Growth of Florida beggarweed [Desmodium tortuosum (Sw.) DC], redroot pigweed (Amaranthus retroflexus L.), chickweed [Stellaria media (L.) Cyrillo], common dandelion (Taraxacum officinale (Weber), and wild mustard [Brassica kaber (DC.) L.C. Wheeler var. pinnatifida (Stokes) L.C. Wheeler] was severely reduced in soils with low pH.
54 citations
TL;DR: Emulsifiable linseed oil was more effective than petroleum oil in reducing the detrimental effect of low humidity and of simulated rainfall and emulsifiable Linseed oil reduced the redroot pigweed control with bentazon with high humidity at 30 C compared to bentazon applied alone or with petrole- um oil.
Abstract: Experiments were conducted in the growth chamber and greenhouse to determine the influence of humidity, tem- perature, simulated rainfall, and oil additives with bentazon (3-isopropyl- lH-2, 1 ,3-benzothiadiazin-(4) 3H-one 2,2-diox- ide) upon redroot pigweed (Amaranthus retroflexus L.) con- trol. Generally, bentazon gave increased redroot pigweed con- trol with high rather than low humidity. However, the in- creased weed control with high humidity was greater at 10 C than at 20 or 30 C. A simulated rainfall within 24 hr after bentazon application reduced redroot pigweed control. A sim- ulated rainfall of 650 L/ha within 1.5 hr after bentazon appli- cation increased control of redroot pigweed, while more than 1300 L/ha simulated rainfall decreased redroot pigweed con- trol. Emulsifiable linseed oil and petroleum oil additives to the spray reduced the detrimental effect of low humidity and sim- ulated rainfall upon redroot pigweed control with bentazon. Emulsifiable linseed oil was more effective than petroleum oil in reducing the detrimental effect of low humidity and of simulated rainfall. However, emulsifiable linseed oil reduced the redroot pigweed control with bentazon with high humidity at 30 C compared to bentazon applied alone or with petrole- um oil.
TL;DR: Yellow nutsedge (Cyperus esculentus L.) was studied to determine the relationship between physical character of tubers and sprouting habits, and prolonged refrigerated storage of tuber caused an increased number of multiple sprouts, a decreased initial and subsequent sprouting interval, and a short life.
Abstract: Yellow nutsedge (Cyperus esculentus L.) was studied to determine the relationship between physical character of tubers and sprouting habits. All tuber lots studied, which averaged from 157 to 662 mg per tuber, sprouted and grew well under greenhouse conditions. Longevity (the time between initial planting and death) increased with tuber weight. Weight of the third and fourth sprouts equalled that of the first and second sprouts for heavy tubers, but sprout weight decreased for light tubers. Detaching the plants at 2-week intervals from the tubers which produced them allowed all buds present to sprout. However, when the plants were detached at 4-week intervals, a reduction in the number of sprouts and a decrease in longevity were observed. Allowing plants to grow for 8 weeks before detaching did not cause any further decrease. Number of buds, number of sprouts, number of multiple sprouts, the time interval between first planting and first sprout, and the time interval between successive sprouts did not vary with initial tuber weight. Prolonged refrigerated storage of tubers caused an increased number of multiple sprouts, a decreased initial and subsequent sprouting interval, and a short life.
TL;DR: Using a modified in vivo nitrate reductase assay, all photosynthetic inhibitors tested were shown to effectively block light-dependent nitrite reduction in green leaf tissue as discussed by the authors, and the degree of inhibition was a function of herbicide concentration reaction solution.
Abstract: Using a modified in vivo nitrate reductase assay, all photosynthetic inhibitors tested were shown to effectively block light-dependent nitrite reduction in green leaf tissue. Nitrate reduction continued so that nitrite accumulated. Ni- trite, vacuum infiltrated into leaf tissue, disappeared linearly with time when incubated in the light. Nitrite, vacuum in- filtrated with a photosynthetic inhibitor, did not disappear but accumulated to even higher levels. The degree of inhibition of nitrite reduction was a function of herbicide concentration Reaction solution. The aqueous reaction solution contained 0.05 M KNO3, 0.05 M KH2PO4, 0.3% Tergitol 15-S-7 sur- factant (a non-ionic linear alcohol ethoxylate3) and 4% eth- anol (v/v). Final pH was adjusted to 7.5 with 3 N KOH. When herbicides were included in the reaction solution, they were first dissolved in absolute ethanol and brought to proper vol- ume with the reaction solution minus ethanol. Final concen- tration of ethanol in all solutions was 4%.
TL;DR: Applied as a postemergence broadcast spray, glyphosate injured soybeans severely at rates higher than 0.3 kg/ha, but did not satisfactorily control yellow nutsedge at rates less than 2.2kg/ha.
Abstract: Laboratory, greenhouse, and field experiments were conducted in 1972 and 1973 on the efficacy of controlling yellow nutsedge (Cyperus esculentus L.) in soybeans [Glycine max (L.) Merr.] with bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide], glyphosate [N-(phosphonomethyl)glycine], and perfluidone [1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide]. Young nutsedge plants (four- to six-leaf stage) were more susceptible to foliar sprays of the three herbicides than were older (six- to eight-leaf stage) plants. Foliar application of bentazon resulted in slow acropetal translocation of the herbicide, but killed the parent tubers. Good coverage of the foliage by bentazon sprays is essential, because the bentazon frequently kills only the foliage contacted by the spray. Applied as a postemergence broadcast spray, glyphosate injured soybeans severely at rates higher than 0.3 kg/ha, but did not satisfactorily control yellow nutsedge at rates less than 2.2 kg/ha. Perfluidone was active on yellow nutsedge when applied to either soil or foliage; yellow nutsedge was controlled best with preplant incorporated treatments at 4.5 kg/ha. Applications of 4.5 kg/ha perfluidone in the field significantly injured soybeans and reduced yields.
TL;DR: In this paper, a simplified version of the isobole method of Tammes (23) is presented as a method which can be readily applied by weed scientists to determine the validity of data on plant responses to herbicide combinations.
Abstract: Several methods of evaluating plant responses to combinations of herbicides are discussed. They include: a direct-plot of percent response vs toxic units; determining ID50 (dosage that causes a 50% reduction in growth of the treated plant) for each herbicide and for each combination; percent response vs log-dosage; double reciprocal procedures; probit analysis, and calculation of expected values. A simplified version of the isobole method of Tammes (23) is presented as a method which can be readily applied by weed scientists to determine the validity of data on plant responses to herbicide combinations. Definitions are proposed which classify plant responses to herbicide interactions as additive, synergistic, antagonistic, or enhancement. Four points are listed that will improve the quality of data obtained from experiments on combinations.
TL;DR: In this article, ammonium sulfate was added to the spray solution of guava spray to increase the absorption of 14C-picloram in the upper stem and attached leaves.
Abstract: Piclorara (4-amino-3,5,6-trichloropicolinic acid) her- bicidal activity on seedlings of guava (Psidium guajava L.), strawberry guava (Psidium cattleianum Sabine), and dwarf beans (Phaseolus vulgaris L. 'Bountiful') was increased by adding ammonium sulfate to the spray solution. Picloram ac- tivity tended to increase with increasing ammonium sulfate concentration up to 10% (w/v), but by the end of each experi- ment ammonium sulfate concentrations above 0.5% were gen- erally equally effective. The absorption of 14C-picloram by strawberry guava leaves was increased about five-fold by 0.5% and 10% ammonium sulfate. There was about four times more 14C-picloram in the upper stem and attached leaves when ammonium sulfate was added than with picloram alone. Am- monium sulfate at 0.5% increased picloram absorption by four-fold in guava, but there was no increase in the amount of picloram translocated acropetally. Picloram absorption by dwarf beans, measured by difference between the amount of picloram applied and the amount recovered, was increased by 0.5% and 1O% ammonium sulfate by a similar magnitude as on guava species.
TL;DR: In this paper, single and repeated applications of MSMA (monosodium methanearsonate) with and without 2,4-D (2.4-dichlorophenoxy)acetic acid, metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one], and methazole [2-(3, 4-dishlorophenyl)-4-methyl-1,2,4)-oxadiazolidine-3,5
Abstract: Single and repeated applications of MSMA (monosodium methanearsonate) with and without 2,4-D [(2,4-dichlorophenoxy)acetic acid], metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5(4H)one], and methazole [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-di-one] were evaluated for control of large crabgrass (Digitaria sanguinalis L. Scop.) and goosegrass (Eleusine indica L. Gaertn.). Large crabgrass was controlled satisfactorily at Griffin in 1972 and 1973 with a single application of 1.7 kg/ha of MSMA, however, repeated applications were required for similar control at Griffin in 1974 and at Blairsville in 1973 and 1974. Repeated treatments at 0.6 kg/ha resulted in satisfactory large crabgrass control in only 2 of 3 years at Griffin and 1 of 3 experiments at Blairsville. The optimum time interval between the first and second MSMA treatments (average 1973 and 1974) was 12 days for the 1.1 kg/ha rate and anytime between 12 and 19 days for the 1.7 and 2.2 kg/ha rates. There was no advantage in large crabgrass control from treatments of methazole, metribuzin, or combinations of MSMA + 2,4-D when compared with MSMA. Single applications of 1.1 kg/ha of metribuzin or 2.2 kg/ha of methazole resulted in excellent goosegrass control without causing any permanent injury to common bermudagrass [Cynodon dactylon (L.) Pers.]. Repeated treatments of 3.3 kg/ha of MSMA were required to obtain satisfactory goosegrass control.
TL;DR: The concentration of EPTC and diallate inhibiting lipid synthesis falls into the physiological range of these herbi- cides, explains some metabolic effects of these compounds, and fits as the mode of activity of these herbicides.
Abstract: EPTC (S-ethyl dipropylthiocarbamate) (33 iM ) and diallate (S-(2,3-dichloroallyl)diisopropylthiocarbamate) (90 ,uM) inhibited the incorporation of 6 mM acetate-2-14 C (Ac*) by 80% and 65%, respectively, and the incorporation of 0.5 ,uM malonate-2-14C (Mal*) by 32% and 26%, respectively, into the lipids of spinach (Spinacia oleracea L.) chloroplasts. The inhibition of Ac* or Mal* incorporation into lipids was not observed in the presence of excess Ac* or Mal*, respectively. Incorporation of palmitate-l1-14C and oleate-1_ 4C into chlo- roplast lipids was inhibited by EPTC and diallate. Mal* incor- poration into dienoic fatty acids was inhibited by EPTC and diallate. The concentration of EPTC and diallate inhibiting lipid synthesis falls into the physiological range of these herbi- cides, explains some metabolic effects of these compounds, and fits as the mode of activity of these herbicides.
TL;DR: In this paper, it was shown that weeds were not reduced in 1969 when weeds were allowed to compete for 4 or 2 weeks, whereas in 1970 and 1971 weed competition for 7 or fewer weeks did not result in yield reductions.
Abstract: Cotton maintained free of annual grass and broadleaf weeds for 6 or more weeks after emergence in 1969 produced maximum yields, whereas in 1970 and 1971, 8 or more weeks of weed-free maintenance were required. Nitrogen applications at planting of 67 and 100 kg/ha did not influence the weed-free requirement of cotton in any year. Cotton yields were not reduced in 1969 when weeds were allowed to compete for 4 or 2 weeks. In 1970 and 1971 weed competition for 7 or fewer weeks did not result in yield reductions. Nitrogen did not affect the competitive relationship between cotton and weeds in 1969 and 1971. In 1970, however, cotton tolerated only 6 weeks of competition at the zero nitrogen rate, whereas it tolerated 7 weeks of competition at the 67 and 100 kg/ha nitrogen rates. Height and stem diameter of cotton were less reliable indicators of the crop-weed relationship than was yield. Neither height nor stem diameter of cotton revealed a consistent difference in the competitive relationship at the three nitrogen rates.