bluuebunny/crossref_metadata_2025 huggingface dataset:
Phytotoxicity and Yield Response of Broad Bean (Vicia faba) to Glyphosate
Authors: Mesa-García J. , De Haro A. , García-Torres L.
Published: May 2019

The tolerance of broad bean (Vicia fabaL. Moruna and Alameda) to glyphosate [N-(phosphonomethyl)glycine] was studied under field conditions. Chlorosis, rolling of apical leaves, and reduced growth were the typical symptoms caused by glyphosate on broad bean plants. Visual phytotoxicity from glyphosate at 60 and 120 g ae/ha was very slight. Moderate or severe crop injury was caused by glyphosate at 360 and 600 g ae/ha, when applied before blooming. Seed yields were 2, 4, 9, 23, and 47% lower than the control after glyphosate applications at 60, 120, 240, 360, and 600 g ae/ha, respectively, when averaged over stages of growth and locations. Broad bean was more susceptible to glyphosate at the vegetative stage, when the plants had five to seven nodes, and less susceptible at the late-flowering and pod-bearing stage. Double applications of glyphosate at 120 g ae/ha reduced seed yield more than 10% compared with similar treatments at 60 g ae/ha, regardless of growth stage. Glyphosate decreased seed yields mainly by reducing the number of pods per plant, but germination, fiber content, and gross energy of the seeds were not altered.
Activity Loss of Ethofumesate in Dry Soil by Chemical Degradation and Adsorption
Authors: McAuliffe David , Appleby Arnold P.
Published: May 2019

Ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] was applied to dry soils (2%, w/w moisture content) that were either wetted immediately or remained dry for 1 to 8 days prior to wetting. Two degradation products were isolated with thin-layer and column chromatography from soils that were kept dry for 4 days before wetting. The major product was identified as 2,3-dihydro-3,3-dimethyl-2-oxo-5-benzofuranyl methanesulfonate which accounted for more than 80% of the degradation products. The products were detected 1 day after application to dry soil (between 1 and 3% moisture content), while at moisture contents greater than 3% (w/w) very little ethofumesate was degraded. Radiolabeled ethofumesate and breakdown products were extracted with methanol from dry and wetted soils, and the soil samples were oxidized to quantify nonextractable radioactivity. The percentage of nonextracted ethofumesate was at least 5% greater in dry soil than in wet soil. Activity loss of ethofumesate applied to dry soil probably is due to both chemical degradation and strong adsorption.
Differential Susceptibility of Field Bindweed (Convolvulus arvensis) Biotypes to Glyphosate
Authors: Degennaro Francis P. , Weller Stephen C.
Published: May 2019

Biotypes of field bindweed (Convolvulus arvensis L. ♯3 CONAR) identified in Indiana varied widely in susceptibility to glyphosate [N-(phosphonomethyl)glycine] but not to 2,4-D [(2,4-dichlorophenoxy)acetic acid] or bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] in field tests. Significant differences in injury to two of the biotypes occurred with glyphosate applied at 1.12 to 4.48 kg ai/ha in greenhouse tests. Differences of greater than 70% in injury rating, root and shoot dry weight, and shoot regrowth dry weight occurred between the two biotypes at 2.24 kg/ha glyphosate. The susceptibility of the tolerant biotype at 2.24 kg/ha glyphosate was decreased by 40% as it increased in age, while the susceptible biotype sustained complete foliar necrosis when treated at all plant ages tested. Susceptibility differences between the two biotypes could not be correlated to differences in leaf stomatal or epidermal cell number. These studies suggested that the variable control of field bindweed observed in the field may be due to the occurrence of biotypes within a given population of this weed which differ in their susceptibility to glyphosate.
Johnsongrass (Sorghum halepense) Competition in Soybeans (Glycine max)
Authors: Williams C. S. , Hayes Robert M.
Published: May 2019

Johnsongrass [Sorghum halepense(L.) Pers., ♯3SORHA] dry weight and johnsongrass culms/ha at harvest were more negatively correlated with soybean yield reductions than the number of johnsongrass plants/ha present at 4 to 6 weeks after planting. However, plant numbers can be determined in sufficient time to implement control measures to prevent yield reduction. Prediction equations for estimating soybean yield at various johnsongrass populations are Ŷ = 1776 + 424e-.023x2for 0.25-m row spacing and Ŷ = 1668 + 643e-.004x2for the 1-m row spacing, where Ŷ = estimated yield and x = the number of johnsongrass plants/10 m2. Full-season heavy johnsongrass competition reduced soybean yields from 59 to 88%. Soybeans in the 1-m row spacing were more competitive with low johnsongrass densities than in the 0.25-m row spacing. The johnsongrass-free requirement for soybeans was 4 weeks after planting and soybeans could not tolerate heavy infestations of johnsongrass for more than 5 weeks without loss in yield potential. Application of sethoxydim {2-[1-(ethoxyimino)-butyl]-5-[2-ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one} at 3 or 4 weeks after planting was effective in controlling heavy infestations of johnsongrass and preventing yield reductions due to competition.
Germination and Dry-Matter Accumulation in Dimorphic Achenes of Tansy Ragwort (Senecio jacobaea)
Authors: Baker-Kratz Ann L. , Maguire James D.
Published: May 2019

Mature achenes from tansy ragwort (Senecio jacobaea L. ♯3 SENJA) capitula borne on lower branches had greater average dry weights and higher percentage germination than those closer to the apex, but these higher averages were obtained because more achenes in these samples were filled. Physiological maturity was attained in ray achenes 21 days past flowering (DPF), 24 DPF in peripheral disk achenes, and 27 DPF in central disk achenes. Maximum germination occurred at 18 DPF in ray and peripheral disk achenes and at 21 DPF in central disk achenes. Neither achene type was shown to have innate dormancy. Disk and ray achenes germinated most rapidly at alternating temperatures of 30/20 C.
Efficiency of Chemical and Mechanical Methods for Controlling Weeds in Peanuts (Arachis hypogaea)
Authors: Bridges David C. , Walker Robert H. , McGuire John A. , Martin Neil R.
Published: May 2019

Research was conducted from 1978 through 1980 at Headland, AL, to evaluate the use of herbicides, mechanical cultivation, and hand-hoeing as components of a total weed control system for peanuts (Arachis hypogaeaL.). Herbicides or two cultivations alone failed to provide acceptable weed control, peanut yields, or net returns for the 3-yr period. However, adding two cultivations to the herbicide treatments produced acceptable weed control, peanut yields, and net returns for the 3-yr period. Average peanut yield for herbicide(s) plus two cultivations was 3200 kg/ha with an average net return of $260/ha. Two cultivations plus two hoeings without herbicide(s) produced good results with an average 3-yr yield of 3380 kg/ha and a net return of $280/ha. Herbicide(s) plus two cultivation treatments that had net returns equal to two cultivations plus two hoeing treatments were: dinoseb (2-sec-butyl-4,6-dinitrophenol) at 5.0 kg ai/ha applied at ground-cracking ($300/ha); dinoseb + alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] at 1.7 + 3.4 kg ai/ha applied at ground-cracking ($310/ha); and alachlor at 4.5 kg/ha applied preemergence ($320/ha). Treatments containing herbicide(s) plus two cultivations plus two hoeings did not substantially improve weed control, peanut yields, or net returns over herbicide(s) plus two cultivations.
Vernalization Requirements for Flowering of Jointed Goatgrass (Aegilops cylindrica)
Authors: Donald William W.
Published: May 2019

Jointed goatgrass (Aegilops cylindrica Host. ♯3 AEGCY) has a quantitative requirement for vernalization in order to flower. In greenhouse and field studies, increasing periods of vernalization progressively reduced the number of days needed for plants to mature following transfer from the cold treatment to favorable growing conditions. Plants that had been vernalized at 3 ± 2 C for 8 weeks as imbibed seed took 120 days to flower following transfer to the greenhouse. Unvernalized controls flowered 197 to 222 days after planting in the greenhouse. Lengthening periods of vernalization from 2 to 8 weeks increased the number of seedheads per plant and dry weight per seedhead. Vernalized plants partitioned more dry matter into seedheads than unvernalized controls. The ratio of seedhead dry weight to vegetative shoot dry weight increased with duration of vernalization, even though vernalization did not alter total shoot dry-matter production. In field studies, plants that were established in the fall flowered sooner and more synchronously after resumption of growth in the spring than those that were planted in the spring and flowered in the summer. Plants seeded after May failed to flower in the same summer.
Effect of Soybean (Glycine max) Interference on Eastern Black Nightshade (Solanum ptycanthum)
Authors: Quakenbush Laura S. , Andersen Robert N.
Published: May 2019

When grown without soybean [Glycine max(L.) Merr.] interference, eastern black nightshade (Solanum ptycanthumDun.) planted in May produced as many as 7000 berries and 800000 seeds per plant. Eastern black nightshade planted in mid-July produced as many as 100 berries, but those planted in mid-August failed to produce berries. Eastern black nightshade produced less than 85 berries per plant when planted with soybeans in May, 0 to 3 berries per plant when planted into soybeans in June, and no berries when planted into soybeans in July. However, when soybeans were defoliated in July to simulate hail injury, eastern black nightshade that had been planted with soybeans in May produced up to 1600 berries per plant, and those planted into the defoliated soybeans in July produced up to 58 berries per plant. We suggest, therefore, that in vigorously growing soybeans, control of eastern black nightshade emerging in the row would only be required through June to prevent berry production. If, however, the soybean canopy were disturbed by hail or other factors, eastern black nightshade seedlings emerging in late July or early August might produce berries by soybean harvest.
Texas Gourd (Cucurbita texana) Control withFusarium solanif. sp.cucurbitae
Authors: Boyette C. Douglas , Templeton George E. , Oliver Lawrence R.
Published: May 2019

An indigenous soil-borne fungus was isolated from infected seeds and seedlings of Texas gourd [Cucurbita texana(A.) Gray] and evaluated as a mycoherbicide. The pathogen was identified asFusarium solaniApp. & Wr. f. sp.cucurbitaeSnyd. & Hans. OnlyCucurbitaspecies were susceptible in host range tests. Ample quantities of microconidia for greenhouse and field plot inoculum were produced in shake culture on Richards' solution. Granular inoculum for field plot tests was produced in 5% (w/w) cornmeal/sand medium. In controlled-environment experiments, inoculated Texas gourd seedlings were killed over a range of air temperatures from 16 to 40 C. Optimum air temperature for disease development was 26 to 30 C. Complete kill of 4- and 8-cm-tall seedlings was achieved after 3 weeks when sprayed until runoff with a microconidial suspension containing 2.0 × 106spores/ml. Texas gourd seedlings were effectively controlled in field plots (99% maximum) with liquid or granular inoculum. Soil samples from infested plots indicated that the fungus persists up to 12 months in a fine sandy loam, but after 12 months inoculum levels were insufficient to cause disease on seedlings grown under optimum conditions for disease development.
Temperature Effects on Growth and Leaf Production in Three Weed Species
Authors: Flint Elizabeth P. , Patterson David T. , Mortensen David A. , Riechers George H. , Beyers Jan L.
Published: May 2019

Sicklepod (Cassia obtusifoliaL. ♯6CASOB), hemp sesbania [Sesbania exaltata(Raf.) Cory ♯ SEBEX], and showy crotalaria (Crotalaria spectabilisRoth. ♯ CVTSP) were grown in controlled-environment greenhouses with day/night temperatures of 23/17, 26/20, 29/23, and 32/26 C. Plant height, leaf area, and total dry weight at 53 days after planting increased significantly with temperatures between 23/17 and 29/23 C in sicklepod and showy crotalaria, and between 23/17 and 32/26 C in hemp sesbania. In all species, leaves were produced more rapidly as temperature increased. Axillary branch leaf production was greatest at 29/23 C in sicklepod, and at 29/23 and 26/20 C in showy crotalaria; hemp sesbania showed little axillary branch development. Total dry-matter production in all species was closely correlated with leaf area duration, but not with net assimilation rate. Differences in total main stem leaf area in all species were primarily due to differences in leaf number rather than to differences in leaf size at maturity.
Penetration, Translocation, and Metabolism of Acifluorfen Following Pretreatment with Mefluidide
Authors: Hook Barbara J. , Glenn Scott
Published: May 2019

The penetration, translocation, and metabolism of acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} in ivyleaf morningglory [Ipomoea hederacea(L.) Jacq. ♯3IPOHE], velvetleaf (Abutilon theophrastiMedic. ♯ ABUTH), common cocklebur (Xanthium pensylvanicumWallr. ♯ XANPE), and soybean [Glycine max(L.) Merr.] were studied. An application to plants of 0.3 kg ai/ha mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} 0, 3, 5, or 7 days prior to treatment with14C-acifluorfen often altered one or more of the physiological processes under study. Pretreatment of ivyleaf morningglory with mefluidide 3, 5, or 7 days prior to application of14C-acifluorfen increased penetration of14C and decreased metabolism of acifluorfen, while translocation was unaffected. All mefluidide treatments increased penetration of14C-acifluorfen into velvetleaf, while the 3-, 5-, and 7-day pretreatments decreased acifluorfen metabolism. Penetration of acifluorfen into common cocklebur was unaffected by pretreatment with mefluidide. However, the 7-day mefluidide pretreatment of common cocklebur increased translocation of14C into the upper leaves and decreased acifluorfen metabolism. Penetration and translocation of the radiolabel from14C-acifluorfen in soybean was unaffected by pretreatment with mefluidide. Metabolism of acifluorfen by soybean was decreased by the 0-day mefluidide treatment but was unaffected by the 3-, 5-, or 7-day mefluidide pretreatment.
Abscisic Acid and Sucrose Control of Velvetleaf (Abutilon theophrasti) Ovule Development in Vitro
Authors: Thompson Laura K. , Leather Gerald R. , Hale Maynard G.
Published: May 2019

The culture of ovules excised from velvetleaf (Abutilon theophrasti Medic., ♯4 ABUTH) capsules 5 days after anthesis was used to measure the effects of abscisic acid (ABA) and sucrose on embryo development and prevention of precocious germination. ABA at 1 × 10-7 M combined with 6% sucrose in the medium for the first 14 days of culture increased embryo development but prevented precocious germination. Higher concentrations of ABA inhibited embryo development. Without ABA, precocious germination increased directly with the concentration of sucrose in the medium, and embryos died. In vivo, ABA reached its highest concentration in ovules 5 days after anthesis but was undetectable after 16 days. Parental control of embryo development may involve ABA and an increasing concentration of osmoticum as seeds dehydrate during maturation.
Reversal of Cation-Induced Reduction in Glyphosate Activity by EDTA
Authors: Shea Patrick J. , Tupy Duane R.
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine] phytotoxicity to greenhouse-grown wheat (Triticum aestivumL. ‘Centurk’) was greatly reduced by Ca2+in the carrier solution. Addition of ethylenediaminetetraacetic acid (EDTA) restored glyphosate phytotoxicity in hard water and increased phytotoxicity in deionized water. The phytotoxicity of 0.1 kg ae/ha glyphosate plus 1.0% (w/v) EDTA was equal to that observed for 0.2 kg/ha of the herbicide alone in deionized water or 0.4 kg/ha in water containing 200 ppm Ca2+. EDTA was more compatible with glyphosate in combination with X-77 or MON-0011 nonionic surfactant than with cationic surfactant (contained in a commercial formulation). Phytotoxicity could be increased by adding EDTA and nonionic surfactant to the latter formulation. EDTA increased glyphosate phytotoxicity to wheat when applied in water that contained high levels of calcium and bicarbonate. Glyphosate activity was greater at pH 4 than at pH 6 or 10, but EDTA was equally effective at pH 4, 6, or 10 for all levels of calcium tested up to 800 ppm. NaHCO3probably reduced phytotoxicity by increasing the pH of the glyphosate solution.
Herbicidal Activity of Fluazifop-Butyl, Haloxyfop-Methyl, and Sethoxydim in Soil
Authors: Buhler Douglas D. , Burnside Orvin C.
Published: May 2019

Fluazifop-butyl {(±) butyl 2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid}, haloxyfop-methyl {methyl-2-[4-[[3-chloro-5-(trifluoromethyl-2-pyridinyl] oxy] phenoxy] propanoic acid}, and sethoxydim {2-[1-(ethoxyimino)-butyl]-5-[2-ethylthio)propyl-3-hydroxy-2-cyclohexen-1-one}exhibited soil herbicidal activity to annual grass species in greenhouse and field experiments. Control of forage sorghum [Sorghum bicolor(L.) Moench. ‘Rox Orange’] with all three herbicides was greater when seeds were planted at or near the soil surface than when planted 2, 4, or 6 cm deep. Imbibition of the herbicides by forage sorghum and soybean [Glycine max(L.) Merr.] seeds did not reduce germination at concentrations of 10-3M or lower, but forage sorghum seedling survival and vigor were reduced by herbicide concentrations as low as 10-7M. Fluazifop-butyl, haloxyfop-methyl, and sethoxydim were more phytotoxic when applied to the root zone than the shoot zone. Haloxyfop-methyl exhibited the longest soil residual control in the field followed by fluazifop-butyl and sethoxydim. Haloxyfop-methyl and fluazifop-butyl controlled simulated shattercane [Sorghum bicolor(L.) Moench. ♯3SORVU] in soybeans with preemergence and early postemergence applications, whereas control from similar applications of sethoxydim was limited and variable.
Postemergence Control of Red Rice (Oryza sativa)
Authors: Barrentine William L. , Street Joe E. , Kurtz Mark E.
Published: May 2019

Mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide}+bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] at 0.14 + 0.84 kg ai/ha was the most injurious of five herbicide treatments applied once to one- to two-leaf red rice (Oryza sativa L. ♯3 ORYSA). The most injurious treatment to five-to six-leaf red rice was DPX Y6202 {ethyl [2-[4-[6-chloro-2-quinoxalinyl]oxy]phenoxy] propionate} at 0.56 kg ai/ha. Two applications, regardless of red rice growth stage, of all treatments except fluazifop {[±]-butyl-2-[4-[[5-trifluoromethyl]-2-pyridinyl] oxy] phenoxy] propanoate} resulted in 86 to 99% injury.
Response of Bermudagrass (Cynodon dactylon), Quackgrass (Agropyron repens), and Wirestem Muhly (Muhlenbergia frondosa) to Postemergence Grass Herbicides
Authors: Hicks Charles P. , Jordan Thomas N.
Published: May 2019

Under greenhouse conditions, approximately 50% visible control of bermudagrass [Cynodon dactylon(L.) Pers. ♯3CYNDA], quackgrass [Agropyron repens(L.) Beauv. ♯ AGRRE], and wirestem muhly (Muhlenbergia frondosaL. ♯ MUHFR) was obtained using 0.56 kg/ha glyphosate [N-(phosphonomethyl)glycine], CGA-82725 {2-propynyl-2-[4-([3,5-dichloro-2-pyridinyl] oxy) oxy)phenoxy propanoate}, 0.28 kg/ha fluazifop-butyl {(±)-butyl 2-[4-[(5-(trifluoromethyl)-2-pyridinyl)oxy] phenoxy] propanoate}, sethoxydim {2-[1-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}, and 0.11 kg/ha haloxyfop-methyl [methyl 2-(4-((3-chloro-5-(trifluoromethyl)-2-pyridinyl)oxy)phenoxy)propanoate]. Except for quackgrass, sethoxydim and fluazifop-butyl reduced shoot regrowth in plants clipped 3 to 6 h after treatment Sethoxydim required a 24-h duration on quackgrass foliage to reduce growth. Fresh weights of haloxyfop-methyl- and CGA-82725-treated plants required a 12- to 24-h clipping for reduced regrowth in all species. For all herbicides and species tested, little or no regrowth occurred when plants were clipped 48 h after treatment. A 1-h interval between split applications of sethoxydim and a 24-h interval between split applications of fluazifop-butyl and haloxyfop-methyl reduced fresh weights of bermudagrass regrowth when compared to an equivalent single rate. Regrowth of treated quackgrass indicated a 24-h interval was required for reductions with split applications of sethoxydim, fluazifop-butyl, and haloxyfop-methyl. Wirestem muhly regrowth was reduced after a 1-h interval between applications. In all species, superior control was obtained using two half-rate applications compared to one full-rate application.
Future Needs in Weed Science
Authors: McWhorter C. G.
Published: May 2019

Losses due to weeds in the United States and the cost of their control are now more than $20 billion annually (35). Of this total, $13 billion represents a 10% annual loss in agricultural production that includes not only the direct competition of weeds to reduce crop yields but also the reduced quality of produce, livestock losses, and increased cost of fertilizer, irrigation, harvesting, grain drying, transportation, and storage. In addition, farmers spend more than $7.2 billion to control weeds each year. About 43% of the expenditures to control weeds is the retail cost of herbicides, $3.1 billion, in 1980 (15). The value of herbicides sold in 1984 will probably be about 15% higher than in 1980. An additional $4.1 billion represents the cost of tillage and hand labor required for weed control (35). The total loss of over $20 billion represents an indirect annual weed tax of about $85 on each individual living in the United States.
Effects of Herbicides on Endomycorrhizal Fungi in Florida Citrus (Citrusspp.) Soils
Authors: Nemec Stan , Tucker David
Published: May 2019

Herbicide effects on vesicular-arbuscular mycorrhizal fungi were studied in greenhouse and field tests. In field plots treated with a bromacil (5-bromo-3-sec-butyl-6-methyluracil) and diuron (3-[3,4-dichlorophenyl]-1,1-dimethylurea) mixture, fungus infection was similar to levels present in cultivated plots. A slight reduction of infection occurred in roots of grove trees in a simazine (2-chloro-4,6-bis [ethylamino]-s-triazine) plus paraquat (1,1′-dimethyl-4,4′-bipyridinium ion)-treated plot compared to a cultivated plot. In the greenhouse studies, diuron, bromacil, and trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) had no apparent effect onGlomus etunicatusBecker and Gerd. and plant growth. Paraquat, PPG 844 {1-(carboethoxy) ethyl 5-[2′-chloro-4′-(trifluoromethyl) phenoxy]-2-nitrobenzoate} and simazine adversely affected plant growth and the fungus.
Bas 9052 Effects on Leaf Photosynthesis and Growth
Authors: Gealy David R. , Slife Fred W.
Published: May 2019

BAS 9052 {2-[1-(ethoxyimino)-butyl]-5-[2-(ethylthio)-propyl]-3-hydroxy-2-cyclohexene-1-one} and difenopenten {4-[4-[4-(trifluoromethyl)phenoxy]phenoxy]-2-pentenoic acid} concentrations less than 1% (w/w) did not normally inhibit apparent photosynthesis (AP) of corn (Zea maysL. ‘Mo 17 × B73′) leaves for at least 24 h. However, leaf growth was completely inhibited by BAS 9052 within 24 h. Leaf AP was initially more inhibited in soybean (Glycine maxL. ‘Corsoy’) than in corn by each herbicide, but within 48 h soybean AP was usually recovering and plants grew normally. Because inhibition of corn leaf growth preceded that of AP, leaf photosynthesis could not be a primary mode of action for BAS 9052.
Temperature Effects on Glyphosate Absorption, Translocation, and Distribution in Quackgrass (Agropyron repens)
Authors: Devine Malcolm D. , Bandeen John D. , McKersie Bryan D.
Published: May 2019

Absorption, translocation, and distribution of14C-glyphosate [N-(phosphonomethyl)glycine] were examined in quackgrass [Agropyron repens(L.) Beauv.] plants growing at 10/8, 15/12, and 21/18 C day/night temperatures at 300 μE·m-2·s-1. Absorption of14C-glyphosate followed similar trends in all environments, apart from an initial delay at the highest temperature. Approximately 67% of the applied14C-glyphosate was absorbed after 120 h. Glyphosate translocation to the rhizomes was initially slower in plants growing at 10/8 C than at the higher temperatures, but after 24 h continued at a rate similar to that observed at the higher temperatures. CO2exchange rates (CER) were only slightly influenced by temperature between 5 and 25 C, which may explain the lack of temperature effect on the rate of glyphosate translocation. Approximately 47% of the applied14C-glyphosate was recovered in the rhizomes and associated roots 120 h after application in all environments. Glyphosate accumulated predominantly in new rhizomes under all growing conditions.
Comparison of Atrazine Absorption by Underground Tissues of Several Plant Species
Authors: Price Thomas P. , Balke Nelson E.
Published: May 2019

Excised roots of corn (Zea maysL. ‘B73 × Mo 17′) and oat (Avena sativaL. ‘Goodfield’) and potato (Solanum tuberosumL. ‘Kennebec’) tuber slices absorbed14C-atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] in a similar manner during short (1 to 30 min) absorption periods. Within 30 min, atrazine concentrations in tissues and ambient solution were equal. After 24 h of absorption, corn roots contained the most14C, followed in order by velvetleaf (Abutilon theophrastiMedic.) roots, oat roots, and potato tuber slices. Corn and velvetleaf accumulated14C to concentrations above the ambient solution. Efflux of14C was slower for corn than oat, potato, and velvetleaf. Metabolism of atrazine to hydroxyatrazine [2-hydroxy-4-(ethylamino)-6-(isopropylamino)-s-triazine] accounted for accumulation and slow efflux of14C in corn. These experiments show that initial, rapid absorption of atrazine is comparable, but long-term accumulation differs among these tissues.
Tolerance of Tomato (Lycopersicon esculentum) Cultivars to Metribuzin
Authors: Gawronski Stanislaw W.
Published: May 2019

Twenty-six cultivars of tomatoes from several countries were divided into four metribuzin [4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one] tolerance groups: tolerant, semi-tolerant, semi-susceptible, and susceptible. Early maturity and tolerance to metribuzin were correlated (r = −0.78) in the field experiment and (r = −0.72) in a sinking leaf-disc bioassay. New super early cultivars were especially sensitive to metribuzin. Chlorophyll a and b content were not highly correlated with tolerance to metribuzin. Metribuzin rates used for weed control are close to toxic concentrations for very early cultivars of tomatoes. Plants in the 9-leaf stage were less sensitive than plants in the 5- or 7-leaf stage. Metribuzin tolerance came at later stages in early maturing cultivars than in later maturing cultivars.
Off-Site Movement of Hexazinone in Stormflow and Baseflow from Forest Watersheds
Authors: Neary Daniel G. , Bush Parshall B. , Douglass James E.
Published: May 2019

Four forest watersheds (1 ha each) in the upper piedmont of Georgia were treated with hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione] pellets3 at a rate of 1.68 kg ai/ha. From the end of April, 1979, until May, 1980, 26 storms were monitored to determine movement of hexazinone and two of its metabolites [A: 3-(4-hydroxycyclohexyl)-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione, and B: 3-cyclohexyl-6-(methylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione] in runoff water. Residues in runoff peaked in the first storm after application (mean concentration of 442 ± 53 ppbw), and declined with subsequent storms in a power curve function: Conc. (ppbw) = 405 × rate × (1 + 0.44 × days)-1.1. Loss of hexazinone in storm runoff averaged 0.53% of the applied herbicide, with Storms 1 and 17 accounting for 59.3% of the chemical exported. Storm 1 had high residue concentrations and low runoff volume, while Storm 17 contained only low residue levels but a very large stormflow. Hexazinone was the predominant compound in the runoff of all 26 storms. Metabolites A and B occurred in runoff in low-to-trace concentrations (<23 ppbw) for up to 7 months after application. Subsurface movement of hexazinone appeared in streamflow 3 to 4 months after application and produced an additional loss of 0.05%. A second-order perennial stream below the treated watersheds periodically contained hexazinone residues of <44 ppbw.
An Economic Threshold Model for Weeds in Soybeans (Glycine max)
Authors: Marra Michele C. , Carlson Gerald A.
Published: May 2019

A model for determination of economic thresholds, or minimum weed population densities justifying the use of postemergence herbicide treatment, for five weed species in soybeans [Glycine max(L.) Merr.] is presented. Sensitivity analysis was performed on the model with respect to economic, statistical, and agronomic variables. The model was refined to include uncertainty about lost field days during the spraying period. Predictions from both the simple and refined models were consistent with economic theory. It was also determined that the economic threshold is sensitive to choice of data-collection ranges and functional form in weed-interference studies.
Sicklepod (Cassia obtusifolia) Management in Soybeans (Glycine max)
Authors: Sherman Mary E. , Thompson Lafayette , Wilkinson Robert E.
Published: May 2019

Greenhouse and on-farm tests were conducted in North Carolina in 1979 and 1980 to evaluate sicklepod (Cassia obtusifoliaL. # CASOB) management in soybeans [Glycine max(L.) Merr.]. All postemergence herbicide applications gave better sicklepod control when applied following vernolate [S-dipropylthiocarbamate) preplant incorporated than when applied following alachlor [2-chloro-2,6-diethyl-N-(methoxymethyl)acetanilide] preemergence. This resulted from decreased fatty alcohols and hydrocarbons in the epicuticle of vernolate-treated sicklepod. When applied sequentially to vernolate, toxaphene (chlorinated camphene, 67 to 69% chlorine) plus an oil concentrate and acifluorfen {5-[2-chloro-4-(trifluoromethyl)phenoxy]-2-nitrobenzoic acid} applied postemergence to the first true-leaf stage of sicklepod resulted in 95 and 90% control, respectively. Linuron [3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea] and metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] applied alone or as tank mixes with 2,4-DB [4-(2,4-dichlorophenoxy)butyric acid] provided greater than 90% sicklepod control when applied postemergence-directed to soybeans. Metribuzin was more injurious to soybeans than linuron.
Response of Live Oak (Quercus virginiana) and Understory Vegetation to Herbicides
Authors: Meyer Robert E. , Bovey Rodney W. , Bouse L. Fred , Carlton James B.
Published: May 2019

Live oak (Quercus virginianaMill. # QUEVM) on the Texas Coastal Prairie was treated with herbicides using ground and aerial application methods. Tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea} and pellets of buthidazole {3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone} at 2.2 kg ai/ha were the most effective herbicides, killing 60 to 95% of the live oak. Tebuthiuron pellets 3.2 mm in diam were more effective than the wettable powder at 1.1 kg/ha. Bay Met 1486 {N-[5-(ethylsulfonyl)-1,3,4-thiadiazole-2-yl]-N,N′-dimethylurea}, Dowco 290 (3,6-dichloropicolinic acid), hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H, 3H)-dione], and picloram (4-amino-3,5,6-trichloropicolinic acid) reduced the live oak canopy at 2.2 kg/ha whereas 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} were ineffective. Foliage-active herbicides generally were most effective in reducing the live oak canopy during the year of application. The soil-active herbicides generally were most active 1 or 2 yr after herbicide application. All herbicides reduced the live oak cover sufficiently to allow an increase in grass cover 2 to 4 months after treatment. Tebuthiuron at 2.2 kg/ha maintained a high degree of grass cover at least 2 or 3 yr after treatment.
Effect of Moisture Stress on Canada Thistle (Cirsium arvense) Control
Authors: Lauridson Thomas C. , Wilson Robert G. , Haderlie Lloyd C.
Published: May 2019

Laboratory experiments were conducted to determine the effect of moisture stress on the absorption and translocation of14C-labeled picloram (4-amino-3,5,6-trichloropicolinic acid), dicamba (3,6-dichloro-o-anisic acid), and glyphosate [N-(phosphonomethyl)glycine] within the Canada thistle [Cirsium arvense(L.) Scop. # CIRAR] plants. The absorption and translocation of picloram and dicamba were unaffected by moisture stress. Absorption and translocation of glyphosate to the roots and apical meristem of Canada thistle was reduced by increasing moisture stress. Weekly differential irrigation of Canada thistle field plots during the summers of 1980 and 1981 established three soil moisture regimes averaging −6.6, −11.3, and −15.0 bars at the time of herbicide treatment. When Canada thistle control was evaluated 1 year after application of glyphosate, dicamba, and picloram at 2.5, 1.1, and 0.6 kg/ha, respectively, no differences in Canada thistle shoot control were found between moisture stress treatments.
Triclopyr for Control of Honey Mesquite (Prosopis julifloravar.glandulosa)
Authors: Jacoby Pete W. , Meadors Cecil H.
Published: May 2019

Triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy] acetic acid} was aerially applied at four locations in Texas to determine effectiveness of the amine and ester formulations for the control of honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell # PRCJG]. The ester formulation was superior to the amine in most trials. Honey mesquite control with triclopyr amine was comparable to that with 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] while control with triclopyr ester was similar to that attained with a 1:1 mixture of 2,4, 5-T and picloram (4-amino-3,5,6-trichloropicolinic acid). Honey mesquite control obtained with a 1:1 mixture of 2,4,5-T and dicamba (3,6-dichloro-o-anisic acid) was intermediate between that with the 2,4,5-T and picloram mixture and that with 2,4,5-T alone. Efficacy of triclopyr increased as rates were increased from 0.3 to 0.6 kg ae/ha and from 0.6 to 1.1 kg/ha. Triclopyr formulations were effective when applied in either water or diesel oil/water emulsions. Honey mesquite control from triclopyr in combination with picloram was generally comparable to that from the mixture of picloram and 2,4,5-T.
Response of Four Bermudagrass (Cynodon dactylon) Cultivars to Fall-Applied Herbicides
Authors: Johnson B. J.
Published: May 2019

Combination treatments of 2,4-D [(2,4-dichlorophenoxy)acetic acid] + mecoprop {2-[(4-chloro-o-tolyl) oxy] propionic acid} + dicamba (3,6-dichloro-o-anisic acid) injured actively growing bermudagrass [Cynodon dactylon(L.) Pers. # CYNDA] immediately after treatment. Treatments made at the normal (1.1 + 0.6 + 0.1 kg ai/ha) rate in August, September, or October, did not affect winter survival. A triple rate (3.3 + 1.8 + 0.3 kg/ha) delayed growth of ‘Tifgreen’ and ‘Tifdwarf’ more the following April than ‘Tifway’ and ‘Ormond’. Due to a reduction in turf stand from herbicide treatments, the cover of common chickweed [Stellaria media(L.) Cyrillo # STEME] was higher in plots to which herbicides were applied in August or September than in untreated plots. The cover of weeds was lower in Tifway and Ormond plots than in Tifgreen and Tifdwarf plots.
Effect of No-till Systems on Weed Control and Yields of Continuous Winter Wheat (Triticum aestivum)
Authors: Cleary Charles L. , Peeper Thomas F.
Published: May 2019

Experiments were conducted from 1979 to 1982 to determine whether selected herbicide treatments applied before or after harvest would provide adequate weed control without the use of tillage between crops in continuous winter wheat (Triticum aestivumL.) production systems. of the herbicide treatments evaluated, only oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) at 2.2 kg ai/ha applied prior to wheat maturity adequately controlled summer annual weeds each year. Populations of yellow nutsedge (Cyperus esculentusL. # CYPES) and/or clammy groundcherry (Physalis heterophyllaNees) increased from continued preharvest use of oryzalin in no-till treatments and were greater than those resulting from conventional tillage or various postharvest no-till treatments containing glyphosate [N-(phosphonomethyl)glycine]. After 4 yr, populations of winter annualCruciferaespp. at one location were lower in treatments that had poorer control of summer annual weeds or volunteer wheat. At a second location, winter annual broadleaf species were more numerous in conventionally tilled than in no-till treatments. Wheat yields obtained with no-till treatments were lower than yields obtained with conventional tillage in seasons favorable for high yields.
Eight Years of Herbicide and Nitrogen Fertilizer Treatments on Kentucky Bluegrass (Poa pratensis) Turf
Authors: Murray J. Jack , Klingman Dayton L. , Nash Ralph G. , Woolson Edwin A.
Published: May 2019

Annual applications of three nitrogen (N) rates, two broadleaf herbicides, and six annual-grass herbicides in Kentucky bluegrass (Poa pratensisL.) turf were made from 1974 to 1981. With each increment increase in N (2, 4, and 6 kg N/200 m2), the percentage cover of crabgrass (Digitariaspp.) and number of common dandelion (Taraxacum officinaleWeber # TAROF) plants were reduced when compared with the next lower rate. There was an interaction between crabgrass control by the annual-grass herbicides and fertilizer rates. When highly effective herbicides were used, there were no differences in crabgrass control related to N rate. When less effective herbicides or no annual-grass herbicides were used, there were great changes directly related to N rate. Each increment of increased N rate increased the turf quality rating. The broadleaf herbicides resulted in differential quality ratings, although differences were relatively small. Highest quality ratings were for plots treated with the three most effective annual-grass herbicides. Residues in the ppb range of some herbicides were detected in soils sampled about a year after the eighth annual herbicide treatments, but residues were below the phytotoxic level and therefore would have had no effect on control of weeds.
Sugarbeet (Beta vulgarisL.) Response to Simulated Herbicide Spray Drift
Authors: Schroeder Galen L. , Cole Darrell F. , Dexter Alan G.
Published: May 2019

Dicamba (3,6-dichloro-o-anisic acid), 2,4-D [(2,4-dichlorophenoxy)acetic acid], and picloram (4-amino-3,5,6-trichloropicolinic acid) were applied as simulated spray drift to sugarbeets at several growth stages. When applied at early growth stages 2,4-D tended to decrease root yield but decreased purity and extractable sucrose content by as much as 54% when applied at later growth stages. Dicamba at 0.14 kg ae/ha and 2,4-D at 0.28 kg ae/ha decreased extractable sucrose/ha and tended to decrease root yield at harvest while picloram at 0.028 kg ae/ha did not significantly reduce root yield or sucrose content at harvest compared to the control. All rates of 2,4-D from 0.035 to 0.28 kg ae/ha increased sucrose losses during post-harvest storage at 5 C and 95% relative humidity. Dicamba and picloram at 0.14 and 0.028 kg ae/ha, respectively, caused similar storage losses. Sugarbeets that are inadvertently exposed to 2,4-D, dicamba, or picloram spray drift during the growing season should be processed immediately after harvest.
Subsurface Placement Methods for Metribuzin and Trifluralin
Authors: Khalifa Mustafa A. , Wittmuss Howard D. , Burnside Orvin D.
Published: May 2019

Metribuzin [4-ammo-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] at 0.4 kg ai/ha controlled rape (Brassica hitraMoench. # SINAL) when applied 2.5 to 10 cm deep in a horizontal layer or in lines 1 to 4 cm apart. Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0.8 kg ai/ha did not control ‘Rox Orange’ forage sorghum [Sorghum bicolor(L.) Moench. # SORVU] satisfactorily when applied in a subsurface layer, in lines, or in vertical bands 1, 2, and 3 cm apart up to 10 cm deep. Applications of trifluralin at 1.1 kg ai/ha in vertical bands followed by 0.6 kg ai/ha mixed in the surface 2.5 cm controlled forage sorghum as well as or better than surface application followed by incorporation. The combined subsurface and surface trifluralin placement systems were effective for application depths up to 7.5 cm and band spacings up to 2 cm wide. The development of effective subsurface herbicide injection systems would make the use of herbicides requiring incorporation feasible in reduced tillage crop production systems.
Relationships Between Phenylalanine Ammonia-Lyase Activity and Physiological Responses of Soybean (Glycine max) Seedlings to Herbicides
Authors: Hoagland Robert E. , Duke Stephen O.
Published: May 2019

The effects of 16 herbicides from 14 different chemical classes on levels of soluble protein, hydroxyphenolics, anthocyanin, and chlorophyll were determined in light- and dark-grown soybean [Glycine max(L.) Merr. ‘Hill’] seedlings. Growth-reducing concentrations of the herbicides were supplied to 3-day-old dark-grown soybean seedlings in liquid culture. Soluble protein (per axis) was reduced by fluridone {1-methyl-3-phenyl-5-[3-(trifluoromethyl)phenyl]-4(1H)-pyridinone}, paraquat (1,1′-dimethyl-4,4′-bipyridinium ion), perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide}, and propanil (3′,4′-dichloropropionanilide) 24 or 48 h after treatment. In light-grown plants, soluble hydroxyphenolic compound levels were decreased on a per axis basis after 48 h by all chemical treatments except by atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], the methyl ester of diclofop {2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate}, DSMA (disodium methanearsonate), fluridone, MH (1,2-dihydro-3,6-pyridazinedione), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], TCA (trichloroacetic acid), and 2,4-D [(2,4-dichlorophenoxy)acetic acid]. Total chlorophyll content in hypocotyls of these seedlings was decreased by fluridone, metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5 (4H)-one], norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3 (2H)-pyridazinone], paraquat, and 2,4-D, but others had no significant effect. Anthocyanin accumulation in hypocotyls of 48-h light-grown seedlings was decreased by atrazine, fenuron (1,1-dimethyl-3-phenylurea), metribuzin, norflurazon, paraquat, propanil, and propham (isopropyl carbanilate). Phenylalanine ammonia-lyase (PAL) activity (previously reported work) was positively correlated with anthocyanin levels in tissues after treatment with these 16 herbicides, but not with glyphosate [N-(phosphonomethyl)glycine]. There was, however, no correlation between extractable PAL activity and chlorophyll, soluble hydroxyphenolic compounds, or soluble protein content. These results indicated that extracted PAL activities usually reflect relative in vivo activities and that PAL activity is limiting to phenylpropanoid synthesis in vivo.
Weed Control in a Low-Till Oat (Avena sativa) - Soybean (Glycine max) Rotation
Authors: Burnside Orvin C. , Carlson David R.
Published: May 2019

Early-preplant herbicide application for uncultivated production of soybean [Glycine max(L.) Merr. ‘Williams’] slot-seeded into untilled oat (Avena sativaL. 'Stout’) stubble was studied. Foliar- and soil-active herbicides were applied to stubble of recently harvested oats to control weeds without tillage so that soil moisture could accumulate during the fallow period. The following spring, five herbicide treatments were applied 0, 2, 4, and 6 weeks prior to soybean planting as well as preemergence to control weeds selectively in uncultivated soybeans. Broadleaf weeds were more effectively controlled than grass weeds, but both were controlled adequately with several herbicide combinations and at all five application times. Selective control of weeds was sufficient to eliminate yield loss of uncultivated soybeans seeded into untilled oat stubble. This production method could provide the Great Plains soybean producer with an effective weed control system while conserving soil, soil moisture, labor, and fuel.
Physiological Response of Common Cocklebur (Xanthium pensylvanicum) to Glyphosate
Authors: Nafziger Emerson D. , Slife Fred W.
Published: May 2019

Thirteen-day-old common cocklebur (Xanthium pensylvanicumWallr. # XANPE) plants were treated with 15 μg glyphosate [N-(phosphonomethyl)glycine] applied to the lowermost true leaves. Growth was inhibited rapidly following treatment. About 56% of applied14C-glyphosate was taken up within 8 h. Within 4 days after treatment, diffusive resistance increased in treated leaves but did not change in untreated leaves. Glyphosate had little effect on nonstructural carbohydrate content of leaves, but soluble carbohydrate levels of stems and roots had increased by 130 and 180%, respectively, by 56 h after treatment. The uptake of33P into roots was unaffected by the herbicide, but transport of P to the aerial tissues was severely inhibited. Effects such as inhibition of P movement could result from inhibition of protein synthesis.
Interference and Temperature Effects on Growth of Cotton (Gossypium hirsutum), Spurred Anoda (Anoda cristata), and Velvetleaf (Abutilon theophrasti)
Authors: Flint Elizabeth P. , Patterson David T. , Beyers Jan L.
Published: May 2019

Effects of temperature and interference were examined in a replacement series experiment with cotton (Gossypium hirsutumL. 'Stoneville 213′), spurred anodaAnoda cristata(L.) Schlecht. # ANVCR), and velvetleaf (Abutilon theophrastiMedic. # ABUTH). Plants were grown in controlled-environment greenhouses at day/night temperatures of 32/23 or 26/17 C, and harvested 14 or 39 days after planting. Height, dry weight, and leaf area at both harvests, and dry matter production and leaf area duration for the harvest interval were significantly greater in all species at 32/23 C than at 26/17 C. Interference reduced the dry weight per plant and leaf area at day 39, and dry matter production for the harvest interval. Cotton was somewhat superior to both weeds as a competitor at 32/23 C, while spurred anoda was somewhat superior to cotton and velvetleaf at 26/17 C.
RIFORME ISTITUZIONALI E SISTEMA POLITICO
Authors: Passigli Stefano
Published: May 2019

Introduzione

Anticipato molti anni or sono dall'acume cntico di alcuni isolati studiosi, a lungo confinato in una cultura politica a ragione o a torto considerata di «destra», adombrato piò volte nel corso degli anni sessanta e settanta, ed esploso finalmente sul finire dell'ottava legislatura, il dibattito sulle riforme istituzionali è ormai non solo un argomento trattato da riviste specializzate o in convegni specialistici, ma è diventato anche uno dei temi dominanti di questa nona legislatura.
COME MIGLIORARE GLI ATTUALI MECCANISMI (E RENDIMENTI) DI GOVERNO
Authors: Urbani Giuliano
Published: May 2019

Introduzione

Il mio tema riguarda il «cuore» del governo, in un sistema politico che opera mediante governi di coalizione: il funzionamento del Consiglio dei ministri e le istituzioni in grado di condizionarne piò da vicino i rendimenti. Il tema è stato scelto in base a due assunti. Primo: per quanto ampia possa essere la nostra fantasia di «riformatori», non penso che nei prossimi cinque/sei anni il sistema politico italiano potrà affrancarsi dalla necessità di ricorrere a governi di coalizione. Secondo: i rendimenti complessivi della democrazia italiana mi sembrano, quindi, strettamente condizionati dai livelli (e dalle modalità) di funzionamento delle maggioranze che essa saprà esprimere e — piò specificamente ancora — dalle «delegazioni di governo» che saranno espresse da queste stesse maggioranze. Dico questo, per anticipare subito le ragioni in base alle quali pro-pongo di delimitare così drasticamente il campo delle possibili riforme in proposito.