bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Monocotyledons to BAS 9052 OH
Authors: Hosaka Hideo , Inaba Hideo , Ishikawa Hisao
Published: May 2019

Postemergence applications of BAS 9052 OH, {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, at 0.25 and 0.5 kg ai/ha were made to 27 temperate and 28 tropical species ofGramineae. Annual bluegrass (Poa annuaL. ♯3POAAN) and rattail fescue (Festuca myurosL. ♯ VLPMY) were resistant to these rates of BAS 9052 OH. Five species of fescue and three species of bluegrass received postemergence applications of BAS 9052 OH at rates of 0.1 to 6.4 kg ai/ha. The germination of seeds and the subsequent growth of the seedlings of these species as influenced by various concentrations of BAS 9052 OH were also studied. Meadow fescue (Festuca pratensisHuds. ♯ FESPR), tall fescue (Festuca arundinaceaSchreb. ♯ FESAR), Kentucky bluegrass (Poa pratensisL. ♯ POAPR), and rough-stalked meadowgrass (Poa trivialisL. ♯ POATR) were most susceptible; annual bluegrass was somewhat less resistant; hard fescue (Festuca longifoliaThuill) was resistant; red fescue (Festuca rubraL. ♯ FESRU) and rattail fescue were very resistant.
Weed Seed Decline in Irrigated Soil after Six Years of Continuous Corn(Zea mays)and Herbicides
Authors: Schweizer Edward E. , Zimdahl Robert L.
Published: May 2019

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on corn (Zea maysL.) production was assessed where corn was grown under furrow irrigation for 6 consecutive years. In one system, 2.2 kg/ha of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] was applied annually to the same plots as a preemergence treatment. In the other system, a mixture of 1.7 kg/ha of atrazine plus 2.2 kg/ha of alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] was applied preemergence, followed by a postemergence application of 0.6 kg/ha of the alkanolamine salts of 2,4-D [(2,4-dichlorophenoxy)acetic acid]. The response of weeds and corn is presented only where atrazine was applied annually because the results were similar between both weed management systems. Weed seeds from eight annual species were identified, with redroot pigweed (Amaranthus retroflexusL. ♯ AMARE) and common lambsquarters (Chenopodium album♯ CHEAL) comprising 82 and 12%, respectively, of the initial 1.3 billion weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of redroot pigweed and common lambsquarters seeds was 99 and 94%, respectively. Very few weeds produced seeds during the first 5 yr, and no weed seeds were produced during the sixth year where atrazine was applied annually. When the use of atrazine was discontinued on one-half of each plot at the beginning of the fourth year, the weed seed reserve in soil began to increase due to an increase in the weed population. After 3 yr of not using atrazine, the weed seed reserve in soil had built up to over 648 million seeds/ha, and was then within 50% of the initial weed seed population. In the fifth and sixth years, grain yields were reduced 39 and 14%, respectively, where atrazine had been discontinued after 3 yr.
Weed Seed Decline in Irrigated Soil after Rotation of Crops and Herbicides
Authors: Schweizer Edward E. , Zimdahl Robert L.
Published: May 2019

The impact of two weed management systems on the weed seed reserves of the soil, on the yearly weed problem, and on barley (Hordeum vulgareL. ‘Steptoe’), corn (Zea maysL. ‘Pioneer 3709′), and sugarbeet (Beta vulgarisL. ‘Mono Hy D2′) production was assessed where these crops were grown in rotation for 6 consecutive years. Weeds were controlled in each crop with a moderate (system I) or intensive (system II) level of herbicides, plus conventional tillage. Weed seeds from seven annual genera were identified, with redroot pigweed(Amaranthus retroflexusL. ♯3AMARE) andChenopodiumcomprising 56 and 30%, respectively, of the initial 1377 million weed seeds/ha that were present in the upper 25 cm of the soil profile. After the sixth cropping year, the overall decline in the total number of weed seeds in soil was 96% in system I and 97% in system II. Over the 6-yr period, about 1.3 times more weeds escaped control in system I than in system II; and within a crop, the fewest number of weeds escaped annually in sugarbeets, and the most in barley. Yields of barley grain, corn silage, and recoverable sucrose were similar each year in the two weed management systems.
Competition of Spreading Dayflower (Commelina diffusa) with Rice(Oryza sativa)
Authors: Smith Roy J.
Published: May 2019

Rough-rice yield of drill-seeded paddy rice (Oryza sativaL. ‘Lebonnet’ and ‘Starbonnet’) at stands of 215 to 270 plants/m2at Stuttgart, Arkansas were reduced 18% by season-long competition of spreading dayflower (Commelina diffusaBurm. f. ♯3COMDI) at a density of 22 plants/m2. Competition durations of 20, 40, 60, or 80 days did not reduce rice yields. None of the durations of competition affected head-rice yields (percent whole milled kernels) or germination of rice seed.
Chlorsulfuron Induction of Leaf Abscission in Velvetleaf (Abutilon theophrasti)
Authors: Hageman Larry H. , Behrens Richard
Published: May 2019

In velvetleaf (Abutilon theophrastiMedic. ♯3ABUTH), accelerated leaf abscission was a conspicuous response following foliar chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} treatment at 35 g ai/ha. Leaf abscission of treated plants was decreased by AVG [L-2-amino-4-(2-aminoethoxy)-trans-3-butenoic acid], an inhibitor of endogenous ethylene production. Chlorsulfuron stimulated ethylene production in the abscission zone and leaves of treated plants and also increased cellulase activity in the abscission zone. Accelerated leaf abscission of velvetleaf following chlorsulfuron application appears to result from chlorsulfuron-induced increases in endogenous ethylene production and cellulase activity.
Temperature Effect on Difenzoquat Phytotoxicity
Authors: Miller Stephen D. , Nalewaja John D. , Dobranski Adam
Published: May 2019

The phytotoxicity of difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) applied to the three-leaf stages of hard red spring wheat (Triticum aestivumL. ‘Waldron’ and ‘Era’), barley (Hordeum vulgareL. ‘Beacon’) and wild oat (Avena fatuaL. ♯ AVEFA) grown under constant, fluctuating, or alternating day-night temperatures was determined in controlled environment chambers. Difenzoquat injury to wild oat and Era wheat was greater at a constant 20 or 30 than at 10 C; however, injury to Waldron wheat was similar at 10, 20, and 30 C. Difenzoquat caused only slight injury to barley, and injury was similar at all temperatures. In Era wheat, selectivity of difenzoquat for wild oat was maximum with a 10-C night temperature in an otherwise 30-C-temperature environment; in Beacon barley selectivity was maximum with 3 or more days of 20- or 30-C posttreatment temperature; and in Waldron wheat selectivity was not adequate at any of the temperatures studied.
Controlling Weeds in Dormant and Nondormant Alfalfa (Medicago sativa)
Authors: Peters Elroy J. , McKelvey Robert A. , Mattas Richard
Published: May 2019

When applied in early February, simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], pronamide [3,5-dichloro-(N-1,1-dimethyl-2-propynyl)benzamide], secbumeton [N-ethyl-6-methoxy-N′-(1-methylpropyl)-1,3,5-triazine-2,4-diamine], and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] effectively removed weedyBromusspecies from established alfalfa (Medicago sativaL.) and increased yields of alfalfa forage. Diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], terbacil (3-tert-butyl-5-chloro-6-methyluracil), and hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine- 2,4(1H,3H)-dione] had no adverse effects on yields of alfalfa when applied in late March. Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) was somewhat less effective for controlling weeds when applied in late March than when applied in February. When applied to weed-free stands of alfalfa after dormancy was broken, metribuzin, terbacil, hexazinone, and simazine, but not pronamide, significantly reduced yields of alfalfa. Terbacil applied immediately after the first cutting did not significantly reduce yields of the second cutting. Terbacil and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] applied when alfalfa had 5 cm of regrowth significantly reduced yields.
Quackgrass (Agropyron repens) Control in Potatoes (Solanum tuberosum) by Sethoxydim
Authors: Ivany Jerry A.
Published: May 2019

In greenhouse and field studies, sethoxydim {2-[1-(ethoxyimino)-butyl]-5-(2-ethylthio)-propyl]-3-hydroxy-2-cyclohexen-1-one} provided good control of quackgrass [(Agropyron repens L. (Beauv.) ♯ AGRRE] in potato (Solanum tuberosum L. ‘Russet Burbank’). Level of control with sethoxydim at 0.6 kg ai/ha in the greenhouse was improved by the addition of a surfactant at 1.0% (v/v) of spray volume. Removal of quackgrass shoots at 6 or 24 h after treatment resulted in decreased control at application rates of 0.6, 1.0, and 1.6 kg ai/ha. Application of sethoxydim at 1.2 or 1.6 kg ai/ha in the field gave excellent control of quackgrass when applied at either the three- or six-leaf stage. Cultivation at 2 days after treatment did not adversely affect level of control obtained. Sethoxydim did not cause any adverse effect on potato yield, but delaying application until the six-leaf stage of quackgrass resulted in yield loss due to quackgrass competition.
The Fate of Oryzalin Applied to Straw-mulched and Nonmulched Soils
Authors: Banks Philip A. , Robinson Edward L.
Published: May 2019

Field experiments to compare the loss of oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) from straw-mulched and nonmulched soils indicated that oryzalin disappeared more rapidly in soils covered by straw in 1980 and 1981 but not in 1982. It appeared that greater rainfall in 1982 was responsible for this difference. Straw mulch on the soil at the time of application reduced the amount of oryzalin reaching the soil surface after subsequent rains or irrigation. Straw levels of 2250 or 4500 kg/ha, when present at the time of treatment, reduced oryzalin concentration in the soil by approximately 15 or 43%, respectively, following 1.3 cm of water applied by sprinkle irrigation. Increasing the straw levels above 4500 kg/ha did not significantly affect the amount of oryzalin detected in the soil beneath the straw mulch.
Chlorsulfuron Reduced Control of Wild Oat (Avena fatua) with Diclofop, Difenzoquat, and Flamprop
Authors: O'Sullivan P. Ashley , Kirkland Ken J.
Published: May 2019

The influence of chlorsulfuron {2-chloro-N-[[(4-methoxy-6-methyl-1,3,5-triazin-2-yl)amino] carbonyl] benzenesulfonamide} on control of wild oat (Avena fatuaL. ♯3AVEFA) when mixed in the spray tank with three herbicides was tested in greenhouse and in field trials at Lacombe and Scott, Canada, during 1981 and 1982. In field experiments, chlorsulfuron mixed with diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy]propanoic acid} caused a 4 to 35% reduction in control of wild oat. Mixtures of chlorsulfuron with difenzoquat (1,2-dimethyl-3,5-diphenyl-1H-pyrazolium) caused a 0 to 19% reduction and mixtures with flamprop {N-benzoyl-N-(3-chloro-4-fluorophenyl)-DL-alanine} a 2 to 30% reduction in control of wild oat. Addition of chlorsulfuron to the wild oat herbicides under greenhouse conditions also resulted in losses in control of wild oat. Increasing the rate of the wild oat herbicide in the mixture tended to overcome these losses.
Early Preplant Herbicide Applications for No-Till Soybean (Glycine max) Weed Control
Authors: Stougaard R. N. , Kapusta George , Roskamp Gordon
Published: May 2019

Several field studies were conducted during 1981 and 1982 to determine whether early preplant (EPP) applications of residual herbicides would prevent the establishment of vegetation before planting no-till soybeans [Glycine max(L.) Merr. ‘Williams’]. Early preplant applications of either cyanazine {2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile} or cyanazine plus oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) were applied in the fall and 3, 2, and 1 month(s) before planting no-till soybeans. In all studies, the treatments prevented vegetation from becoming established before planting, and season-long weed control was achieved with several different treatments. Early preplant cyanazine plus oryzalin provided greater than 90% control for the entire season where grass densities were low. Where grass densities were high (greater than 90% ground cover), EPP cyanazine plus a preemergence application of metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] plus metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] or a postemergence application of sethoxydim {2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} controlled 90% of the weeds, which was equal to or better than the standard preemergence treatments used (80 to 98% weed control).
Tillage Effects and Environmental Influences on Quackgrass (Agropyron repens) Rhizome Growth
Authors: Majek Bradley A. , Erickson Clair , Duke William B.
Published: May 2019

Field experiments were established in 1978 and repeated in 1979 to monitor quackgrass [Agropyron repens (L.) Beauv. ♯3 AGRRE] rhizome growth through a growing season. Quackgrass shoots grew most vigorously when temperatures were moderate. They elongated and differentiated an inflorescence in June. Rhizome apical tips remained belowground in late spring, early summer, and early fall. Quackgrass rhizome tips grew vertically and emerged from the soil in midsummer and late fall. Experiments conducted in growth chambers revealed that photoperiod, temperature, and nitrogen level affected quackgrass shoot and rhizome growth. Shoots grew vigorously at 21C and elongated to differentiate an inflorescence when exposed to a photoperiod of 14 h or longer. Rhizome apical tips remained belowground when plants were grown at 21 C and received 16 or 12 h of light, but the tips curved upward and emerged from the soil when quackgrass was grown at 32 or 10 C, or when the plants received 14 or less than 10 h of light. The temperature and photoperiod responses coordinated to partition the growing season into primary rhizome and rhizome-tiller growth periods.
Response of Concord Grapes (Vitis labrusca) to 2,4-D in Irrigation Water
Authors: Comes Richard D. , Marquis Louis Y. , Kelley Allen D.
Published: May 2019

In field studies 0.1 ppmw ae or less 2,4-D [(2,4-dichlorophenoxy)acetic acid] applied by sprinklers in 5.1 cm of water over 8 h did not affect the number or dry weight of leaves or length of canes of 1-yr-old Concord grape plants (Vitis labruscaL.). A second application at 0.01 ppmw or higher to the same plants 1 yr later reduced growth of leaves, canes, and trunk. Combined effects of root pruning (required to position plants for treatment the second year) and 2,4-D probably account for this apparent anomaly. When 2,4-D was applied annually at 1.0 ppmw or less to established plants for three consecutive years, growth, yield, and fruit quality were not affected. No residues of 2,4-D were detected in the fruit at harvest (detection limit 0.05 ppmw). Grapes treated with 1.0 ppmw 2,4-D developed moderate injury symptoms.
Response of Bermudagrass (Cynodon dactylon) Turf to Winter-Applied Herbicides
Authors: Johnson B. J.
Published: May 2019

Paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), 2,4-D [2,4-dichlorophenoxy)acetic acid], dicamba (3,6-dichloro-o-anisic acid), and 2,4-D plus dicamba were applied as postemergence herbicide treatments in two experiments to weed-free dormant bermudagrass [Cynodon dactylon(L.) ♯3CYNDA] turf in the Piedmont region of Georgia. Herbicides were applied as a split application to separate plots on February 2 plus February 16 and February 16 plus March 3 (± 4 days) on four bermudagrass cultivars (‘Tifway’, ‘Tifgreen’, ‘Tifdwarf’, and ‘Ormond’) in one experiment and to Tifway with vertical mowing treatments for thatch removal in a second experiment. In 2 of 3 years, paraquat applied to dormant turf in February delayed growth of bermudagrass in April. The growth of Tifway and Tifdwarf was retarded more from paraquat at 1.2 kg ai/ha in one year than Tifgreen or Ormond. Dicamba applied alone or with 2,4-D delayed turf growth in early spring more than did 2,4-D alone. In thatch-free turf, selected treatments of paraquat, dicamba, and 2,4-D plus dicamba also delayed spring growth of bermudagrass more than did 2,4-D.
Pendimethalin Phytotoxicity to Velvetleaf (Abutilon theophrasti) and Powell Amaranth (Amaranthus powellii)
Authors: Malefyt Timothy , Duke William B.
Published: May 2019

Velvetleaf (Abutilon theophrastiMedic. ♯3ABUTH) and Powell amaranth (Amaranthus powelliiS. Wats. ♯ AMAPO) control with pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] was dependent on proper timing of application. Preemergence and early postemergence pendimethalin treatments provided effective control, but control rapidly diminished with later postemergence treatments, particularly on Powell amaranth. Time-course studies on the effects of pendimethalin on the growth of these species indicated that pendimethalin inhibited shoot growth by slowing or stopping the production of leaves and branches, as well as reducing leaf size and internode length. Pendimethalin appeared to have its greatest effect on portions of the shoot undergoing cell division.
Growth and Reproductive Characteristics of Field Bindweed (Convolvulus arvensis) Biotypes
Authors: Degennaro Francis P. , Weller Stephen C.
Published: May 2019

Five presumed biotypes were identified among field bindweed (Convolvulus arvensisL. ♯3CONAR) clones collected from a field population near Lafayette, IN. Consistent variations in leaf morphology, floral characteristics, and accumulation of shoot and root biomass were found between biotypes when grown in a controlled environment. The biotypes also differed in their flowering capacity. The earliest flowering biotype formed flowers 23 days before the latest and produced 19 times more flowers per plant, which indicated further differences in seed production potential between biotypes. Pollination studies helped to differentiate biotypes within the population and showed that the presumed biotypes were self-incompatible. Vegetative reproduction potential of the biotypes varied from 1.8 to 74.5% in the number of root buds that developed into shoots. The variability in growth and reproduction observed between these field bindweed biotypes may explain the survival and adaptability of a population of this weed as environmental conditions and control practices change.
Potential Use of Response Surface Analyses for Weed Management in Soybeans (Glycine max)
Authors: Keisling Terry C. , Oliver Lawrence R. , Crowley R. Hugh , Baldwin Ford L.
Published: May 2019

In crop/weed interactions a method is needed to reduce the complex data derived from interference research to a simple form which can be utilized immediately. A response surface technique was utilized in analyses involving densities, duration of interference, interference abilities of different species, and weed growth rates. At high weed densities interfering for long durations, multispecies interference is not additive but at low densities additiveness is approached. Soybean [Glycine max(L.) Merr.] yield loss from multispecies weed interference was calculated by subtracting the percent yield loss from the most competitive weed and then repeating the same procedure for remaining weeds. Interference data for weed species in which fewer data were available were determined by linear interpolation for densities of more comprehensively researched, closely related species. Polynominal regression curves were utilized to predict weed age and future weed size from weed height. These analyses can produce information to assist soybean producers in recognizing economically detrimental threshold levels of weed infestations which require the initiation of control measures.
Effects of Solarization on Soil Weed Seed Populations
Authors: Standifer Leon C. , Wilson Paul W. , Porche-Sorbet Rhonda
Published: May 2019

Clear and black polyethylene mulches were placed over raised seed beds in four studies during a 3-yr period. At intervals during treatment times of up to 12 weeks, soil samples were taken and the recovered seed were tested for germination. The number of seed killed and depths to which they were killed varied with species. The study included natural seed populations of annual bluegrass (Poa annuaL. ♯3POAAN), barnyardgrass (Echinochloa crus-galli(L.) Beauv. ♯ ECHCG), annual species ofCyperus, dayflower (Commelina communisL. ♯ COMCO), and goosegrass (Eleusine indicaL. Gaertn. ♯ ELEIN). After 40 days exposure under clear mulch, seed of dayflower were killed to a depth of 11 cm. Under the same conditions, seed of annualCyperussedges and barnyardgrass were killed only in the upper 3 to 4 cm. After 3 weeks under clear plastic, germinable seed of goosegrass were recovered only at depths greater than 5 cm. Seed in plots under clear polyethylene mulch were killed more quickly than those in plots covered with black polyethylene mulch.
Influence of Bentazon on Absorption and Translocation of Sethoxydim in Goosegrass (Eleusine indica)
Authors: Rhodes G. Neil , Coble Harold D.
Published: May 2019

The absorption and translocation of sethoxydim {2[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} as influenced by bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] were studied in goosegrass [Eleusine indica(L.) Gaertn. ♯3ELEIN]. The presence of bentazon in the treatment emulsion decreased foliar absorption of14C applied as14C-sethoxydim by about half. Significantly less14C was found in the treated leaf, shoot tissue above the treated leaf, shoot tissue below the treated leaf, and roots of plants treated with a mixture of14C-sethoxydim and bentazon than with14C-sethoxydim alone. After 6 h, 3.5% of applied14C was recovered from plant parts other than the treated leaf in the absence of bentazon, compared to 1.1% of that applied in combination with bentazon. The difference in foliar absorption between the two treatments may account for the antagonistic interaction between these herbicides observed in the field.
Growth and Development of Sicklepod (Cassia obtusifolia) Selections
Authors: Retzinger E. James
Published: May 2019

Sicklepod (Cassia obtusifoliaL. ♯3CASOB) seed were obtained from 10 locations in nine southern states, and plants were grown in a nursery for 3 yr. In field experiments, plant height, seed per pod, number of seed per plant, and number of pods per plant varied among seed sources and years. The vegetative growth phase, as measured from emergence to the initiation of the first floral buds, was approximately 30 days shorter for plants grown from the Tennessee source than for those grown from seed collected in Alachua, FL, in all 3 yr. Hand-harvested seed from plants grown from the 10 seed sources that were planted in 1982 were planted beside the original source sicklepod seed in 1983, and both flowered at approximately the same time, indicating self-fertilization. Percent germination of hand-harvested sicklepod seed from the 10 sources ranged from 2 to 11% for 1981 and 3 to 23% for 1982.
Inhibition of Velvetleaf (Abutilon theophrasti) Germination and Growth by Benzyl Isothiocyanate, a Natural Toxicant
Authors: Wolf Rebecca B. , Spencer Gayland F. , Kwolek William F.
Published: May 2019

Benzyl isothiocyanate (BITC) was extracted from mature papaya (Carica papayaL.) seeds and applied to imbibed velvetleaf (Abutilon theophrastiMedic. ♯3ABUTH) seeds. Complete inhibition of germination occurred at a concentration of 6 × 10-4M BITC, and only 28% (compared to controls) of the seeds germinated after 4 days exposure to the 4 × 10-4M treatment. Corn (Zea maysL. ‘DeKalb XL-66′) was unaffected even at higher concentrations; however, 72% of imbibed soybeans [Glycine max(L.) Merr. ‘Tiger’] germinated in 6 × 10-4M BITC. When this natural inhibitor was applied to etiolated velvetleaf seedlings at 4 × 10-4M, 100% died in 2 days.
Atrazine- and Diuron-Resistant Strains ofRhodopseudomonas sphaeroides
Authors: Sutton William F. , Brown Alfred E. , Truelove Bryan
Published: May 2019

Photosynthetic growth of 9 of the 11 known species of the family Rhodospirillaceae was strongly inhibited by atrazine. Growth of a wild-type strain of the bacteriumRhodopseudomonas sphaeroidesvan Niel was almost completely inhibited by 100 μM concentrations of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea]. These herbicides gave 50% inhibition of growth at concentrations of 35 and 25 μM, respectively. Through continuous culture of the wild-typeR. sphaeroidesin the presence of 100 μM atrazine, strains of the organism were selected in which photosynthetic growth was highly resistant to both atrazine and diuron. Members of the genusRhodopseudomonasisolated from two natural ecosystems showed various levels of resistance to 100 μM atrazine, butRhodopseudomonasshowing a high level of resistance were more common among the isolates from a pond-mud sample which had been exposed to runoff from atrazine-treated cropland than from a sample of a lake mud never exposed to triazines.
Resistance to Triazine Herbicides in Horseweed (Conyza canadensis)
Authors: Lehoczki Endre , Laskay Gábor , Pölös Endre , Mikulás József
Published: May 2019

Insensitivity to atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] and certain other herbicides was found in plants of horseweed (Conyza canadensis(L.) Crong. ♯4ERICA) collected from vineyards where atrazine had been applied extensively. There were no differences in the uptake, translocation, or accumulation of radiolabeled atrazine between plants of the susceptible and resistant biotypes. However, atrazine at 1 × 10-4M caused no inhibition of photosynthetic electron transport in resistant leaves. Photosynthetic characteristics of leaves of susceptible and resistant plants showed different sensitivities to atrazine, but similar sensitivities to diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and ioxynil (4-hydroxy-3,5-diiodobenzonitrile). Isolated chloroplast membranes from resistant plants exhibited a resistance factor of 1000 to atrazine but only 10 to 30 to methylthio-s-triazines. DNOC (4,6-dinitro-o-cresol) was found to be more effective in susceptible chloroplasts than in resistant ones. A marked reduction in the galactolipid content, especially digalactosyl diglyceride, was found in resistant leaves. It is suggested that these alterations in lipid content and composition may contribute to atrazine resistance in horseweed.
Studies on Mineral Nutrition of Hydrilla verticillata
Authors: Basiouny Fouad M. , Garrard Leon A.
Published: May 2019

The effects of mineral element uptake on the growth and development of the aquatic plant hydrilla [Hydrilla verticillata (L.f.) Royle.] were studied in a short-term experiment under laboratory conditions. On a dry-weight basis, maximum growth of hydrilla plants was obtained at a 0.016 ppm P and 5 ppm Ca in the growing media. Hydrilla responded favorably to high concentrations of K (40 ppm in the growing media). The presence of 2,4-dinitrophenol (2,4-DNP) reduced uptake of K, Cu, Fe, Mn and did not significantly affect the uptake of Ca or P. Thus the uptake of K, Cu, Fe, and Mn by hydrilla appears to be dependent on metabolic energy.
Alfalfa (Medicago sativa)–Cheat (Bromus secalinus) Competition
Authors: Pike David R. , Stritzke Jimmy F.
Published: May 2019

A study was conducted at two locations to evaluate the effects of cheat (Bromus secalinusL. ♯3BROSE) competition on four seeding rates (4.5, 9.0, 13.5, and 22 kg/ha) of alfalfa (Medicago sativaL. ‘Riley’). Three stages of first harvest (early bud, early bloom, and late bloom) were imposed on fall-planted alfalfa, with and without cheat overseeding, to determine the effects of harvest stage on alfalfa yield and quality. Cheat infestations significantly decreased alfalfa production and forage quality. Increasing the seeding rate of alfalfa only partially offset these losses. Harvesting early helped minimize the effect of cheat competition. First-harvest protein yield of forage was significantly decreased by, cheat overseeding. Total protein yield at first harvest was not affected by cutting stage but did increase with the two higher seeding rates of alfalfa.
Allelopathic Effects of Lantana (Lantana camara) on Milkweedvine (Morrenia odorata)
Authors: Achhireddy Nagi Reddy , Singh Megh
Published: May 2019

Allelopathic effects of lantana (Lantana camaraL. ♯3LANCA) residues (root, shoot), foliar leachates, and the soil (where lantana was grown) on milkweedvine (Morrenia odorataLindl. ♯3MONOD) seed germination and growth over a 30-day period were examined. Foliar leachates or the soil collected from the field where lantana had been growing had no effect on the final germination percentage or the seedling growth of milkweedvine. Incorporation of dried lantana shoot or root material into soil had no effect on the final percentage germination but caused significant reductions in milkweedvine growth over a 30-day test period. Roots were more inhibitory than shoots. Fifty percent of milkweedvine seedlings died within 15 days after germination at 1% (w/w) dried lantana root incorporation into the soil, and higher concentrations increased seedling death. Lantana roots incorporated into the soil produced foliar symptoms such as wilting and desiccation, whereas lantana shoots incorporated into the soil produced yellowing of the foliage of milkweedvine. Allelopathic activity of lantana residues was still strong even after decomposition of lantana residues for 4 weeks prior to the planting of milkweedvine seeds.
Influence of Weed Control Programs in Intensive Cropping Systems
Authors: Glaze N. C. , Dowler C. C. , Johnson A. W. , Sumner D. R.
Published: May 2019

Six multiple-cropping systems composed of: a) turnip (Brassica campestrisspp.rapifera), corn (Zea maysL.), and snapbean (Phaseolus vulgarisL.); b) turnip, peanut (Arachis hypogaeaL.), and snapbean; c) turnip, corn, and turnip; d) turnip, peanut, and turnip; e) snapbean, soybean [Glycine max(L.) Merr.], and cabbage (Brassica oleraceaL.); and f) turnip, cucumber (Cucumis sativusL.), cowpea [Vigna unguiculata(L.) Walp.], and turnip were subjected to nematicide and weed control programs of cultivation or herbicides. Herbicide programs were superior to cultivation in control of weeds. Weeds remaining in the row following cultivation competed severely with crops. Weed species remaining were altered depending on the method of control and crop. Yellow nutsedge (Cyperus esculentusL. ♯3CYPES) increased rapidly in all herbicide programs but not in cultivated plots. Pigweeds (Amaranthusspp.) were controlled by herbicides but increased in cultivated plots. Corn, peanut, soybean, and spring snapbean yields were higher in herbicide treatments than in cultivated treatments. Cucumber was the only crop that had increased yields for both main effects, herbicide and nematicide. Turnip was consistently injured in herbicide treatments, which was believed to be caused by residues from previous crops interacting with pathogens and possible allelopathic effects of decaying organic matter.
Integrated Systems for Control and Management of Downy Brome (Bromus tectorum) in Cropland
Authors: Wicks Gail A.
Published: May 2019

Downy brome (Bromus tectorumL. # BROTE) may be a troublesome weed in winter small grains, perennial legumes, perennial grasses grown for seed, and orchards. In Nebraska, winter wheat (Triticum aestivumL.) yields have been depressed 30% by downy brome populations of 11 to 22 plants/m2(8). In Oregon, downy brome densities of 108 to 160 and 538 plants/m2reduced yields by 40 and 92%, respectively (22, 23). In Idaho, wheat yields were depressed 20 to 40% with 55 to 110 plants/m2(18). Downy brome has also been shown to lower yields and quality of hay from infested fields of alfalfa (Medicago sativaL.) (29). In perennial grass seed fields, downy brome may cause a serious seed quality problem (16). Some grass seed lots have contained as much as 50 to 75% downy brome seed.
Growth Retardant Response of Bean (Phaseolus vulgaris) and Woody Plants to Injections of MBR 18337
Authors: Sterrett John P. , Hodgson Richard H. , Snyder Robert H.
Published: May 2019

The growth retardant activity of MBR 18337 {N-[4-(ethylthio)-2-(trifluoromethyl)phenyl]-methanesulfonamide} was determined by injection into bean plants (Phaseolus vulgarisL. ‘Black Valentine’), California privet seedlings (Ligustrum ovalifoliumHassk.), and saplings of white ash (Fraxinus americanaL.) and red maple (Acer rubrumL.). Height and leaf expansion of bean were inhibited by 8 μg of MBR 18337 per plant in growth chamber studies. Sprout growth of California privet grown in the greenhouse was inhibited for 92 days by 80 μg of MBR 18337 per tree, and the growth in the field of ash and maple saplings was retarded by 3.2 mg of MBR 18337 per tree for an entire growing season with little injury. Radioassays for14C-MBR 18337 indicated rapid translocation of14C-activity in privet from the lower stem to the region of the apical shoot. More than 80% of the MBR 18337 in the xylem and phloem was oxidized within 14 days.
Critical Period of Weed Interference in Transplanted Tomatoes (Lycopersicon esculentum): Growth Analysis
Authors: Weaver Susan E. , Tan Chin S.
Published: May 2019

The critical period of weed interference in transplanted tomatoes (Lycopersicon esculentumMill. 'Springset’) was from 28 to 35 days after transplanting. A single weeding during this period was sufficient to prevent yield reductions. A growth analysis revealed that significant differences in plant dry weight and fruit number between tomatoes from weed-free and weed-infested plots were not apparent until 56 to 70 days after transplanting. The shorter the initial weed-free period, or the longer weeds were allowed to remain in the plots before removal, the earlier reductions in tomato dry weight and fruit number appeared. Weed interference was due primarily to shading rather than water stress. Tomatoes from weed-infested plots had significantly lower stomatal conductances than those from weed-free plots, but did not differ in xylem-pressure potential or in canopy temperature. If tomatoes were kept weed-free for more than 28 days, or when weeds were present for less than 28 days after transplanting, stomatal conductances were not significantly reduced.
Fluridone Adsorption on Mineral Clays, Organic Matter, and Modified Norfolk Soil
Authors: Shea Patrick J. , Weber Jerome B.
Published: May 2019

Adsorption and desorption characteristics of fluridone (1-methyl-3-phenyl-5-[3-txifluoromethyl)phenyl]-4-(1H)-pyridinone} on prepared clays and organic matter were studied in unbuffered and buffered aqueous solutions. In unbuffered aqueous solution the adsorption of fluridone decreased in the order: H-saturated organic matter (H-OM) > Ca-saturated montmorillonite (Ca-mont) > Ca-saturated organic matter (Ca-OM) > kaolinite. Based on the chemistry of fluridone, the nature of the adsorbent, and previously reported studies, the major adsorption mechanisms appear to be pH-dependent adsorption of protonated fluridone and direct protonation of the herbicide at acidic surfaces, supplemented by physical adsorption forces such as van der Waals attractions and charge transfer bonds. The adsorption of fluridone on Norfolk sand (Typic Paleudult; fine-loamy, siliceous, thermic), unmodified (CK), or amended with montmorillonite (HC) or organic matter (HM) at pH 4.0, 5.2, and 7.0 was also studied. Over all adsorption was greatest on HC soil, least on CK soil, and intermediate on the HM soil. In each system adsorption was inversely related to pH. These results were interpreted by comparison with adsorption observed on prepared clay minerals and organic matter.
Response of Calli and Seedlings of Tomato (Lycopersicon esculentum) Cultivars to Metribuzin
Authors: Harrison Howard F. , Bhatt Prashant , Fassuliotis George
Published: May 2019

Hypocotyl callus cultures were established from six tomato (Lycopersicon esculentumL.) cultivars that exhibited differential tolerance to preemergence and postemergence metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] at 0.5 kg ai/ha in the greenhouse. Metribuzin in a low sucrose growth medium inhibited callus growth, but calli were not highly sensitive to the herbicide Differences between cultivars in the response of calli to 50 ppm metribuzin were observed. The degree of tolerance of tomato cultivars to postemergence metribuzin at 0.5 kg/ha was similar to the degree of tolerance of their hypocotyl calli to 50 ppm metribuzin in the growth medium.
Weed Control by Alachlor and Residues in Sweet Potato (Ipomoea batatas) and Soil
Authors: Herman Nancy D. , Monaco Thomas J. , Sheets T. Jack
Published: May 2019

Alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] at 3.4 and 6.7 kg/ha controlled weeds present in sweet potatoes (Ipomoea batatasL. ‘Jewel’, ‘Centennial’, ‘Caromex’) at two locations in North Carolina. Yield was not reduced from slight early season injury observed with the herbicide treatments. Most sweet potato root samples contained less than the detectable limit of 0.05 ppmw of alachlor. At one location, samples of the cultivars Jewel and Centennial that received 6.7 kg/ha contained 0.06 and 0.05 ppmw, respectively. Averaged over locations, residue levels in soil samples from plots treated at 6.7 kg/ha decreased from 1.55 ppmw initially to less than 0.05 ppmw by 16 weeks after application.
Effect of Corn (Zea mays) Population on the Growth of Yellow Nutsedge (Cyperus esculentus)
Authors: Ghafar Zain , Watson Alan K.
Published: May 2019

Increasing the corn (Zea maysL. “CO-OP S265”) population from 33 300 to 133 300 plants per hectare in the field significantly reduced yellow nutsedge (Cyperus esculentusL. # CYPES) above-ground biomass, tuber number, tuber weight and yellow nutsedge height at the end of growing season, and significantly increased corn yield. Photosynthetically active radiation below corn canopies decreased with increasing corn population and corresponded to reductions in yellow nutsedge above-ground biomass, tuber weight and tuber number. These results demonstrate that available light is a major factor in yellow nutsedge competition with corn. The size of yellow nutsedge was also reduced at high corn densities. These results support the use of crop manipulation in an integrated yellow nutsedge management system in corn.
Compatibility of BAS 9052 OH with Acifluorfen and Bentazon
Authors: Hartzler Robert G. , Foy Chester L.
Published: May 2019

Large crabgrass [Digitaria sanguinalis(L.) Scop. # DIGSA] control with BAS 9052 OH {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexene-1-one} was similar whether applied alone or in combination with acifluorfen {5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoic acid}. Combinations of BAS 9052 OH and bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4-(3H)-one 2,2-dioxide] gave decreased grass control compared to BAS 9052 OH alone. This antagonism between BAS 9052 OH and bentazon was eliminated by applying bentazon as a separate application 1.5 h or longer before the application of BAS 9052 OH. A 0.2 h interval between applications of the herbicides decreased large crabgrass control compared to control obtained with BAS 9052 OH applied alone, but the decrease was signifciantly less than occurred with a concurrent application of the two herbicides.
Effect of Alachlor on PEG6000Uptake, Root Osmotic Potential, and Root Leakage
Authors: Vavrina Charles S. , Ashley Richard A.
Published: May 2019

Sweet corn (Zea maysL.rugosa'Seneca Scout’) and soybeans (Glycine maxL. Merr. ‘Kanrich’) were grown in nutrient solutions containing alachlor [2-chloro-2′,6-diethyl-N-(methoxymethyl)acetanilide] at 2.36 × 10-5M, polyethylene glycol MW 6000 (PEG6000) at −2.5 bars osmotic potential, alachlor at 2.36 × 10-5M plus PEG6000at −2.5 bars osmotic potential or with no additions. Sweet corn and soybean roots exposed to alachlor plus PEG6000accumulated significantly more PEG6000than roots exposed to PEG6000alone; increased shoot uptake occurred only in soybean. Alachlor was also shown to significantly increase root osmotic potential and decrease root electrolyte leakage.
Buffelgrass (Cenchrus ciliaris) Responses to Tebuthiuron
Authors: Hamilton Wayne T. , Scifres Charles J.
Published: May 2019

Tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiozol-2-yl]-N,N′-dimethylurea} pellets (20% ai) applied at 0.6, 1.1, or 2.2 kg ai/ha in the spring at two locations and in the fall at a third location on the South Texas Plains did not significantly decrease buffelgrass (Cenchrus ciliarisL. # PESCI) standing crop or foliar cover compared to untreated areas. Buffelgrass standing crop was reduced for 8 months after application of 3.3 and 4.4 kg ai/ha of tebuthiuron to a sandy clay loam in the spring, but the same rates did not reduce standing crop after application to clay loam in the fall. However, buffelgrass foliar cover was reduced following application of 3.3 kg ai/ha or more of the herbicide, regardless of soil. Tebuthiuron applied at 2.2, 3.3, or 4.4 kg ai/ha to sandy clay loam soils killed buffelgrass plants in spots, but production by larger surviving plants compensated for reduction in plant density where 2.2 or 3.3 kg ai/ha were applied.
Genetic Variability for Herbicide Reaction in Plant Populations
Authors: Price Steven C. , Hill James E. , Allard R. W.
Published: May 2019

The level of genetic variation for tolerance to herbicides was quantified in populations of slender wild oat (Avena barbata Brott. # AVEBA), wild oat (Avena fatua L. # AVEFA), and godetia (Clarkia williamsonii Lewis & Lewis) that had not been previously exposed to herbicides. Seedlings of wild oat and godetia were treated with barban (4-chloro-2-butynl-m-chlorocarbanilate) and bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), respectively. The plants were rated for phytotoxic effects following treatment. A one-way analysis of variance on arcsin-transformed phytotoxicity ratings showed significant amounts of inter- and intrapopulation variability for herbicide reaction. Furthermore, the amount of genetic variance for herbicide reaction is higher than expected on the basis of mutation alone, suggesting selection favoring genes conferring herbicide tolerance occurs in natural populations.
Effects of Edging Herbicide Treatments on Bermudagrass (Cynodon dactylon) and Woody Ornamentals
Authors: Johnson B. J.
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine], dalapon (2,2-dichloropropionic acid), or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) applied for edging control of bermudagrass [Cynodon dactylon(L.) Pers. ‘common ‘ # CYNDA] did not injure any of the eight woody ornamental species included in a 3-yr study. Paraquat applied in seven applications per year did not effectively control bermudagrass. Bermudagrass control was variable with glyphosate and dalapon during spring and summer; but repeated treatments at approximately 4-week intervals maintained effective control. In most instances, bermudagrass control was higher with glyphosate than with dalapon during September and October.
Napropamide Binding in Corn (Zea mays) Root Tissue
Authors: Barrett Michael , Ashton Floyd M.
Published: May 2019

Napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide]-binding in excised root segments of corn (Zea maysL. ‘NC + 59′) was confined to cell wall fractions (residue and 500gpellet) remaining after homogenization and to components of the 100 000gsupernatant. Binding increased in both the cell wall and soluble fractions with continued exposure to napropamide. Microautoradiographs revealed that the napropamide bound in the cell walls was located in epidermal, cortical, and stelar tissue. Various proteins were capable of binding napropamide in vitro; however, protease treatment did not liberate the radioactivity bound in the cell wall fragments. Carbohydrate release from the cell wall material with cellulase was not correlated with the solubilization of bound radioactivity and wall carbohydrate monomers did not appear to bind to napropamide in vitro. A portion of the radioactivity found in the soluble components (at 100 000g) was associated with a molecule of MW > 600. The continued influx of napropamide was due to binding to cell wall components and molecules within the cell.
Smallflower Morningglory (Jacquemontia tamnifolia) Germination as Influenced by Scarification, Temperature, and Seeding Depth
Authors: Eastin E. Ford
Published: May 2019

Freshly harvested smallflower morningglory [Jacquemontia tamnifolia(L.) Griseb. # IAQTA] seed germinated best after 25 to 60 s of scarification in an electric scarifier equipped with 100 to 120 grit emery cloth. Optimum temperature for germination was 25C. At 10 and 45C no germination occurred for up to 7 days. Eight and 12 days after planting in silt loam soil there was 85 and 98% emergence of smallflower morningglory from depths of 0.5 to 1 cm, whereas no emergence was observed from depths of 6 cm or greater 12 days after seeding.
Evaluation of Selected Herbicides for Manipulating Herbaceous Rangeland Vegetation
Authors: Petersen Joseph L. , Potter Robert L. , Ueckert Darrell N.
Published: May 2019

Rosering gaillardia (Gaillardia pulchellaFoug. # GAIPU) and other herbaceous broadleaf plants were effectively controlled for one season by sprays of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 1.1 kg ae/ha or glyphosate [N-(phosphonomethyl)glycine] at 1.1 kg ai/ha, or a 4:1 combination of 2,4-D and picloram (4-amino-3,5,6-trichloropicolinic acid) at 0.7 kg ae/ha applied in late March in the southern Rolling Plains of Texas. Production of perennial warm-season grasses increased 428, 480, 728, and 1440 kg/ha on a clay site 7 months after spraying with 2,4-D, 2,4-D plus picloram (4:1), atrazine [2-chloro-4-(ethylamino)-6-isopropylamino-s-triazine], and glyphosate, respectively. Application of 4.4 kg ae/ha of dalapon (2,2-dichloropropionic acid) severely damaged perennial warm-season grasses. Annual cool-season grasses were effectively controlled with sprays of atrazine or glyphosate at 1.1 kg ai/ha or dalapon at 4.4 kg ae/ha. Texas wintergrass (Stipa leucotrichaTrin. & Rupr.) production was greatest on rangeland treated with 2,4-D or 2,4-D plus picloram (4:1).
Loss in Yield of Rapeseed (Brassica napus, B. campestris) Caused by Perennial Sowthistle (Sonchus arvensis) in Saskatchewan and Manitoba
Authors: Peschken Diether P. , Thomas A. Gordon , Wise Robin F.
Published: May 2019

Field studies were conducted in 1979 and 1980 to determine yield losses caused by perennial sowthistle (Sonchus arvensis L. # SONAR) in rapeseed (Brassica napus L., B. campestris L.) fields in Saskatchewan and Manitoba. The relationship between percentage yield loss and density of perennial sowthistle was expressed by the linear regression equation y = −3.81 + 13.76 rdx. Weed survey data indicated that perennial sowthistle occurred in 39% of the rapeseed fields but infested only 7% of the hectares surveyed. Using both the survey data and the yield loss equation, the average annual loss in rapeseed yield was estimated to be 9.4 million kg in Saskatchewan and 6.1 million kg in Manitoba, with a value of 2.6 million and 1.7 million dollars (Cdn.), respectively. Perennial sowthistle occurs with a similar frequency and density in other crops so that the total loss from this weed would be much greater.