bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation and Leaching of Methazole in Soil
Authors: Brockman F.E. , Duke W.B.
Published: May 2019

The degradation and leaching of methazole [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] and metabolites in Elmwood sandy loam soil over time in response to average spring environmental conditions was studied by using soil columns placed on a rainfall simulator in an environmental growth chamber. Methazole was degraded to 3-(3,4-dichlorophenyl)-1-methylurea (DCPMU) and 3-(3,4-dichlorophenyl) urea (DCPU) over a 6-week period following methazole application, during which the soil columns received simulated rainfall of 1.27 cm every fourth day. Methazole level decreased to 27% of the original amount while DCPMU and DCPU levels increased to 53% and 1%, respectively. Of the total radioactivity remaining in the soil columns after 44 days and after 14 cm rainfall, approximately 80% remained above a depth of 6.35 mm.
Electrolytic Conductivity — a Rapid Measure of Herbicide Injury
Authors: Vanstone D.E. , Stobbe E.H.
Published: May 2019

The use of electrolytic conductivity as a measure of cell membrane disruption was tested on buckwheat (Fagopyrum esculentumMoench. cv. ‘Tokyo’) plants which had been sprayed with paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) or oxyfluorfen [2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene]. All treatments which resulted in tissue damage caused significant increases to the solutions where the discs were floated for measurement. The highest conductivity measurement (most membrane disruption) was obtained from paraquat. The highest concentration for each herbicide gave higher conductivity measurements than lower concentrations. A difference in the pattern of conductivity change induced by the two chemicals implies a different mode of action for each.
Adsorption, Mobility, and Degradation of Cyanazine and Diuron in Soils
Authors: Majka J.T. , Lavy T.L.
Published: May 2019

In the field, surface applied cyanazine 2-[[4-chloro-6-(ethylamino)-s-triazin-2-yl] amino]-2-methylpropionitrile and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] did not move below 5 cm in a Monona silty clay loam (Typic Hapludoll) which received 20 cm of water over a 54-day period. In hand-packed soil columns in the laboratory, surface-applied diuron and cyanazine penetrated to depths of 10 and 20 cm, respectively, when leached over a comparable time period and with amounts of water similar to that used in the field. Soil thin layer chromatography and adsorption isotherm studies showed that diuron was adsorbed more strongly than was cyanazine. In general, both compounds were degraded more rapidly at the higher temperatures when incubated at 5, 20, 35, and 50 C over a 20-week period. Degradation was slowest at 5 C in a Valentine loamy fine sand (Typic Ustipsamment). Diuron appeared to break down most readily at 35 C. Cyanazine was usually decomposed by the 10th week at 5 C and the 5th week at higher temperatures.
Persistence of 2,4-D and 2,4,5-T in Chaparral Vegetation and Soil
Authors: Radosevich S.R. , Winterlin W.L.
Published: May 2019

The persistence of 2,4-D [(2,4-dichlorophenoxy) acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] was studied in the chaparral environment. Chamise (Adenostoma fasciculatumH. & A.), grass and forbs, soil surface litter, and soil were sampled for up to 360 days after herbicide (4.5 kg/ha) application. Over 50% of the 2,4-D and 2,4,5-T recovered was found on soil surface litter while 18 to 31% was found on vegetation. Much less herbicide (0.1 to 0.2%) was found in soil (0 to 5 cm) than in foliage or litter. No herbicide residues were found below the 0 to 5 cm soil sample zone. Herbicide residues on foliage and litter decreased rapidly (up to 93%) within 30 days after application but remained constant thereafter until winter rainfall began. Residues of both herbicides were evident in chamise foliage (0.01 to 0.02%), surface litter (0.01 to 0.03%), and soil (0.01%) up to 360 days after application.
The Reversal of Scotoactive Stomatal Behavior in some Woody Weeds by Paraquat and 2,4,5-T
Authors: Rao I. Madhusudana , Swamy P.M. , Das V.S.R.
Published: May 2019

A typical scotoactive stomatal behavior was noticed inCarissa spinarumL.;Gymnosporia emarginataLaws;Maba buxifoliaCl.;Flacourtia sepiariaRoxb.;Dodonaea viscosaL. andRandia malabaricaLamk. This stomatal behavior was reversed artificially by foliar application of paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) at 100 ppmw or 2,4,5-T [(2,4,5-trichlorophenoxy)acetic acid] at 2000 ppmw. The size of the stomatal aperture, stomatal conductance and the rates of transpiration were enhanced significantly by the herbicide treatment. The physiological basis for the induction of desiccation and death of plant organs is thought to be the excessive stimulation of stomatal aperture, stomatal conductance and consequently high rates of transpiration observed here. The data suggest that herbicide-induced desiccation is the consequence of inhibition of scotoactive behavior and increased water loss with attendant desiccation and death of leaves.
Yellow Nutsedge (Cyperus esculentus) Control in Cool Season Turfgrass
Authors: Bingham S.W.
Published: May 2019

Yellow nutsedge (Cyperus esculentusL.) control with herbicides was evaluated with and without competition from turfgrasses. Postemergence applications of cyperquat (1-methyl-4-phenylpryidinium) provided safe selective control of yellow nutsedge in Kentucky bluegrass (Poa pratensisL. ‘Merion’), perennial ryegrass (Lolium perenneL. ‘Manhatten’), and red fescue (Festuca rubraL. ‘Pennlawn’). Pre- and post-emergence applications of perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide} controlled yellow nutsedge when rainfall or irrigation was adequate for good turfgrass growth. Under dry conditions, perfluidone slightly injured Kentucky bluegrass and gave poor control of yellow nutsedge. Bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one2,2-dioxide] was less effective than cyperquat or perfluidone for yellow nutsedge control and required split applications. Bentazon did not injure Kentucky bluegrass. Napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] and Vel 3973 [N-(2,4-dimethyl-5-{[(trifluoromethyl)sulfonyl]amino}phenyl)acetamide] did not provide adequate yellow nutsedge control. Vel 5052 {2-chloro-N-(2,6-dimethyl-phenyl-N-[(1,3-dioxolan-2-yl)methyl] acetamide}showed promise for yellow nutsedge control.
Reciprocal Effects of EPTC, CDEC, and Certain Ions on Their Absorption by Tomato (Lycopersicon esculentum)
Authors: Acosta-Nunez Sebastian , Ashton Floyd M.
Published: May 2019

Absorption experiments were conducted with tomato (Lycopersicon esculentumMill. ‘VF-315’) seedlings using salts at the approximate ratio found in saline irrigation water (NaCl 41.9 mM, CaCl220.9 mM, and MgCl2· 6H2O 10.5 mM) in combination with two herbicides. The osmotic pressure of this salt solution is 0.40 MPa (mega Pascal), which is equivalent to 4.0 bar or about 4.0 atm. EPTC (S-ethyl dipropylthiocarbamate) at 0.25 mM reduced the residual Na+, Ca2+, and Mg2+content relative to the treatment with salts alone. CDEC (2-chloroallyl diethyldithiocarbamate) at 0.1 mM produced similar effects for Na+and Ca2+. The addition of salts to either EPTC or CDEC induced significantly higher concentrations of total and residual herbicide in the tomato seedlings. The data suggest that salts reduce the tolerance of tomato to EPTC and CDEC by increasing absorption of the herbicides. The residual EPTC or CDEC in the tomato seedlings increased as the CaCl2concentrations increased in the incubation medium. A strong linear relationship was found between the calcium content and EPTC or CDEC content in the tomato seedling tissue.
Effect of a Pre-Irrigation Period on the Activity of Ethofumesate Applied to Dry Soil
Authors: McAuliffe David , Appleby Arnold P.
Published: May 2019

Applications of ethofumesate [(±)-2-ethoxy-2,3-dihydro-3,3-dimethyl-5-benzofuranyl methanesulfonate] at rates from 0.3 to 1.4 kg/ha were made in the field to soils of 2 and 30% (w/w) soil moisture. After 2 to 4 days, all soils were irrigated to establish stands of either sweet corn (Zea maysL. ‘Jubilee’) or winter wheat (Triticum aestivumL. ‘Stephens’) used as bioassay species for ethofumesate activity. Ethofumesate, at most rates, was significantly less effective on both corn and wheat when applied to dry soil than to wet soil. In greenhouse studies, ethofumesate activity was significantly greater when incorporated into soil of 12% than 2% (w/w) moisture 2 or 4 days prior to irrigation. An increase in herbicide activity was apparent as the length of time between herbicide application and wetting increased from 2 to 4 days. Analysis of wet (20%, w/w) and dry (2%, w/w) soils treated with equal levels of ethofumesate revealed no loss of herbicide applied to wet soil over a 12-day period, but in the dry soil, the amount extracted after 12 days was 10% of the amount extracted at 0 days. These data and other considerations suggest that chemical degradation of ethofumesate is the most likely mechanism for the activity loss in dry soil.
Wild Garlic (Allium vineale) Control with Glyphosate
Authors: Troutman Barry C. , King John W. , Frans Robert E.
Published: May 2019

Growth chamber studies and field trials were conducted to evaluate the toxicity of glyphosate [N-(phosphonomethyl)glycine] and certain other herbicides to wild garlic (Allium vinealeL.). Toxicity to wild garlic increased with increasing rates up to 6 kg/ha. Glyphosate was more toxic to wild garlic when applied in spray volumes of 125 to 500 L/ha than in greater volumes. Addition of surfactant did not increase toxicity or absorption rates of 3 kg/ha of glyphosate, but did increase the advantage of 2 kg/ha of glyphosate over 2,4-D [(2,4-dichlorophenoxy)acetic acid]. When glyphosate was sprayed on wild garlic plants at 3 kg/ha, then washed off after 2, 4, 8, 16, and 32 h, absorption of a biologically significant amount of glyphosate required 8 h, and toxicity increased through the 32-h exposure. Injury, which increased as mowing was delayed up to 12 days after application, indicated that significant quantities of glyphosate were translocated between 3 to 12 days after treatment in a field test. Glyphosate; 2,4-D; 2,4-D + mecoprop {2-[(4-chloro-o-tolyl)oxy] propionic acid} + dicamba (3,6-dichloro-o-anisic acid); and VEL-4207 [N-phenyldiethanolamine-bis-(2-methoxy-3,6-dichlorobenzoate)], applied in a sequence of either spring-fall-spring or fall-spring, were compared for wild garlic control. All herbicides tested controlled wild garlic, but glyphosate was more effective than 2,4-D after spring-fall-spring applications. All spring-fall-spring treatments except 2,4-D + mecoprop + dicamba significantly reduced the number and weight of hardshell bulbs present 8 weeks after the last treatment. The initial treatment in the spring-fall-spring sequence was necessary to reduce hardshell bulb populations the second spring. One year after treatment wild garlic reinfested all plots.
Soil Persistence of Herbicides for Corn, Sorghum, and Soybeans during the Year of Application
Authors: Burnside O. C. , Schultz M. E.
Published: May 2019

Herbicides used in corn(Zea maysL.), sorghum [Sorghum bicolor(L.) Moench], and soybeans [Glycinemax (L.) Merr.] were applied in the spring and their persistence into late summer was determined during 1974 to 1976. Composite soil samples from the top 5 cm of field plots were taken each August and bioassayed in the greenhouse. Bioassay species used were winter wheat [Triticum aestivumL.) and soybeans for herbicides used in corn and sorghum, and winter wheat and white mustard(Brassica hirtaMoench) for herbicides used in soybeans. Soil persistence of triazine herbicides caused more injury to winter wheat, soybeans, and white mustard than any other class of herbicides tested. Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] showed the most soil persistence of the five triazines evaluated. At normal field application rates, herbicides other than the triazines showed little injury to the bioassay plants. Soil persistence of herbicides was further reduced when combinations of reduced rates of each herbicide were utilized. Herbicides used for spring applications in corn showed more soil persistence in August than did the herbicides for sorghum, while herbicides for soybeans generally were least persistent. Postemergence herbicide applications resulted in more injury in bioassay species than preplant incorporated or preemergence applications. Persistence of some herbicides will restrict certain options to the grower such as changing crops in case of crop failure, fall planting of winter wheat, double cropping, or certain crop rotations.
Effect of Five Thiocarbamate Herbicides on Purple Nutsedge(Cyperus rotundus)
Authors: Rincon D. J. , Warren G. F.
Published: May 2019

Five thiocarbamate herbicides, butylate(S-ethyl diisobutylthiocarbamate), EPTC(S-ethyl dipropylthiocarbamate), molinate(S-ethyl-hexahydro-1H-azepine-1-carbothioate), pebulate(S-propyl butylethyl-thiocarbamate), and vernolate(S-propyl dipropylthiocarbamate) were used in the greenhouse at doses of 0.5 to 5 kg/ha incorporated 6 cm deep in a silt loam. Purple nutsedge(Cyperus rotundusL.) tubers were planted 5 cm deep. Three and 9 weeks after treatments were applied, nutsedge plants were harvested. EPTC also was used at doses of 0.25 to 10 kg/ha and plants were harvested every 2 days up to 20 days and every 3 weeks up to 24 weeks. The most effective reduction in the number of sprouts above ground was given by butylate, EPTC, and vernolate followed by pebulate and molinate. Persistence was directly related to level of initial activity. No effect was observed on the number of tubers which sprouted. However, all the thiocarbamates stimulated the number of sprouts produced per nondormant tuber. These sprouts were abnormal and did not reach the soil surface. Treated tubers produced approximately twice as many sprouts as controls. The number of rhizomes produced from the basal bulb was reduced with all the thiocarbamates used, even 24 weeks after treatment for the higher doses.
Effects of Repeated Herbicide Applications on Alfalfa(Medicago sativa)
Authors: Swan D. G.
Published: May 2019

Six herbicides, simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], propham (isopropyl carbanilate), terbacil (3-tert-butyl-5-chloro-6-methyluracil), carbetamide [D-N-ethyllactamide carbanilate (ester)], pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide], and secbumeton [N-ethyl-6-methoxy-N′(1-methylpropyl)-1,3,5-triazine-2,4-diamine] were applied annually for four years to establish forage alfalfa(Medicago sativaL. ‘Washoe’). Downy brome(Bromus tectorumL.) control ranged from 80 to 100%. The average control of broadleaf weeds was 90 to 100% with simazine, terbacil, and secbumeton, compared to 30 to 40% with propham, carbetamide, and pronamide. Only simazine and terbacil were phytotoxic to the alfalfa. Based on weed control and crop tolerance, secbumeton performed best on the coarsetextured soil in this experiment.
Use of Glyphosate in Sod Seeding Alfalfa(Medicago sativa)Establishment
Authors: Moshier Loren , Penner Donald
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine] and EPTC(S-ethyl dipropylthiocarbamate) did not reduce significantly the percent germination of either ‘Saranac’ or ‘Vernal’ cultivars of alfalfa(Medicago sativaL.) grown in petri dishes. Glyphosate at 10−5M significantly reduced shoot length of both cultivars. Vernal alfalfa appeared to be more susceptible to glyphosate than the Saranac cultivar. Soil applications of glyphosate also had no effect on percent emergence of either cultivar and reduced plant height only of Vernal when applied to the soil at 17.9 kg/ha. Applications of glyphosate at 2.2, 4.5, and 9.0 kg/ha to a Kentucky bluegrass(Poa pratensisL.) sod in a simulated sod seeding alfalfa establishment study in the greenhouse reduced dry weight of both alfalfa cultivars; Vernal was affected more adversely than Saranac. Application of 2.2 kg/ha glyphosate in four management systems showed that a 3-day planting delay after spraying reduced growth inhibition of alfalfa seeded in treated sod. These results were similar to those obtained with paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) in these management systems. Kentucky bluegrass clippings treated with paraquat 3 days or less before contact with alfalfa seedlings significantly reduced seedling dry weight. Clippings treated with glyphosate did not reduce alfalfa seedling dry weights significantly.
Toxicity of Soil-Incorporated Trifluralin to Johnsongrass(Sorghum halepense)Rhizomes
Authors: Millhollon R. W.
Published: May 2019

Rhizomes of johnsongrass [Sorghum halepense(L.) Pers.], cut into 2.5-cm or 15-cm lengths, were planted in the field within and below a 7.5-cm layer of soil mixed with trifluralin(a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 0, 1.7, or 3.4 kg/ha. When planted 3.8- and 10-cm deep in nontreated soil, survival was 90% and 69%, respectively, for the longer rhizomes and only 39% and 10%, respectively, for the shorter ones. When planted within trifluralin-treated soil, 95% and 100% of the shorter rhizomes and 54% and 81% of the longer rhizomes were killed at 1.7 and 3.4 kg/ha, respectively. When planted below treated soil, only 11% or 19% of the longer rhizomes were killed. The shorter rhizomes planted below the treated soil survived at less than 10%.
Germination of Wild Poinsettia(Euphorbia heterophylla)
Authors: Bannon J. S. , Baker J. B. , Rogers R. L.
Published: May 2019

Germination studies were conducted on seed of wild poinsettia(Euphorbia heterophyllaL.) collected in 1974 and 1975. Significant differences in germination existed between the seedlots. An alternating temperature regime of 25/35 C was optimum for germination, and no effect of light was noted at this temperature regime. However, light increased germination at temperatures of 25, or 35 C, and decreased it at 10/35 C. Storage of wild poinsettia seeds at 36 C for 2 to 12 weeks caused a significant decrease in dormancy as compared to corresponding storage at 5 C. Seed moisture levels below 7.7% did not seem to affect viability at 5 or 25 C after a storage period of 3 to 9 months. Seed viability decreased rapidly when seed were stored for 3 months at 25 C with a moisture content of 10.8% or at 5 or 25 C with a moisture content of 18.6%. Seeds buried in the fall at a depth of 5 cm germinated extensively in the field 9 months later. Field germination decreased as depth of burial increased.
Influence of Placement of Charcoal on Protection of Cotton(Gossypium hirsutum)from Diuron
Authors: Chandler J. M. , Wooten O. B. , Fulgham F. E.
Published: May 2019

The effectiveness of activated charcoal in protecting seedling cotton(Gossypium hirsutumL. ‘Stoneville 213’) from diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] at 1.78 and 3.55 kg/ha was investigated under field conditions over a 5-yr period. Charcoal did not provide adequate protection when applied through the seed hopper box or sprayed in the seed furrow over each hill. Charcoal at 83 and 167 kg/ha applied as a spot over each hill of cotton gave adequate protection. Shallow incorporation of the charcoal significantly reduced the degree of protection. The optimum combination, providing maximum weed control and minimum crop injury, was diuron at 3.55 kg/ha applied over non-incorporated charcoal at 83 kg/ha.
Yellow Nutsedge(Cyperus esculentus)Control in Kentucky Bluegrass(Poa pratensis)with Bentazon, Cyperquat, and Perfluidone
Authors: Kern A. D. , Meggitt W. F. , Penner Donald
Published: May 2019

Bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4) 3H-one 2,2-dioxide], cyperquat (1-methyl-4-phenylpyridinium), and perfluidone {1,1,1-trifluoro-N-[2-methyl-4-(phenylsulfonyl)phenyl] methanesulfonamide} were evaluated for their potential use as postemergence herbicides for selective yellow nutsedge(Cyperus esculentusL.) control in Kentucky bluegrass(Poa pratensisL.) in field studies. High rates of these herbicides as single or split applications were effective and only slightly reduced verdure of Kentucky bluegrass, indicating excellent selectivity. In greenhouse studies perfluidone exhibited growth retardant properties. Shoot dry weight production was inhibited and root dry weight of treated plants was markedly reduced. These two factors are undesirable features for commercial sod production.
Germination Response of Some Woody Plant Seeds to Electrical Treatment
Authors: Nelson S. O. , Bovey R. W. , Stetson L. E.
Published: May 2019

Seed lots of Macartney rose(Rosa bracteataWendl.), yaupon(Ilex vomitoriaAit.) huisache [Acacia farnesiana(L.) Willd.], and honey mesquite [Prosopis juliflora(Swartz) DC. var.glandulosa(Torr.) Cockerell] were exposed for various periods to radiofrequency (RF) dielectric heating by electromagnetic fields of 10 and 39 megahertz (MHz) at various field intensities in attempts to increase their germination. Both continuous-wave and pulse-modulated exposures were used at 39 MHz. Seed samples were preconditioned at temperatures from 24 to −43 C before exposure. Sixty-Hz a-c and d-c electrical treatments were included in some experiments. Although significant increases in germination were obtained by RF treatment of huisache and honey mesquite seed in some experiments, results with different huisache seed lots were inconsistent. The germination of Macartney rose seed was not increased, and no germination was observed in yaupon, regardless of the treatment employed.
Response of Processing Peas(Pisum sativum)and Annual Weeds to Acetanilide Herbicides
Authors: Jordan G. L. , Harvey R. G.
Published: May 2019

The relative effectiveness of eight acetanilide herbicides for controlling annual weeds in processing peas(Pisum sativumL.) was evaluated in field studies and the susceptibility of peas to injury from these herbicides was studied in both the field and greenhouse. Alachlor [2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] was the most phytotoxic to peas grown in washed silica sand in the greenhouse when the herbicides were applied at concentrations of 2 and 8 mg/L. Field trials conducted over a 2-yr period and simulated rainfall experiments in the greenhouse demonstrated that the phytotoxicity to peas by acetanilide herbicides applied preemergence at 2.2 and 4.5 kg/ha was greatly influenced by subsequent rainfall. When 2.5 cm of simulated rainfall were applied immediately after herbicide application, pea injury increased. Injury to peas was avoided in the field by delaying alachlor application at 2.2 kg/ha until peas began to emerge. This treatment also gave excellent control of annual grass weeds. Greenhouse studies demonstrated that injury to peas by all eight acetanilide herbicides at 2.2 and 4.5 kg/ha could be avoided by delaying application until pea emergence. Alachlor, propachlor (2-chloro-N-isopropylacetanilide), and metolachlor [2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide] gave slightly superior weed control than butachlor [N-(butoxymethyl)diethylacetanilide] and H 22234 [N-chloroacetyl-N-(2,6-diethylphenyl)-glycine ethyl ester].
Enzyme Activities in Prickly Sida(Sida spinosa)Seeds of Different Developmental Stages
Authors: Smith E. W. , Reger B. J. , Egley G. H.
Published: May 2019

Key metabolic enzymes and germination were studied in developing and mature, dormant and nondormant prickly sida(Sida spinosaL.) seeds. Isocitrate dehydrogenase, glucose-6-phosphate dehydrogenase, fructose-1,6-diphosphatase, and phosphofructokinase activities were determined in developing and mature prickly sida seeds. Developing seeds less than 7 days after anthesis and at 17 days or greater after anthesis were unable to germinate. The 7-day-old seeds lacked all but fructose-1,6-diphosphatase activity. The 17-day-old seeds demonstrated all enzyme activities but failed to germinate because dehydration had occurred and seeds were unable to imbibe sufficient water without an afterripening period. Comparison of enzyme activities of dormant and nondormant seeds on incubation showed that only glucose-6-phosphate dehydrogenase was considerably different within the first 8 h of incubation. Nondormant seeds had considerable glucose-6-phosphate dehydrogenase activity before germination (radical protrusion at 8 h), suggesting an active pentose phosphate pathway.
Control of Yellow Nutsedge(Cyperus esculentus)and Other Weeds Before Summer Planting of Alfalfa(Medicago sativa)
Authors: Linscott D. L. , Hagin R. D. , Tharawanich T.
Published: May 2019

After land was plowed in the spring and prepared for planting, yellow nutsedge(Cyperus esculentusL.) was allowed to develop to heights of 10 to 12 and 20 to 25 cm. Either glyphosate [N-(phosphonomethyl)glycine] or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) was applied to emerged yellow nutsedge and other annual weeds at rates of 0.5, 1, 2, and 4 kg/ha. Half of the plots were double-disked 3 days after herbicide applications, and then all plots were planted with alfalfa(Medicago sativaL. ‘Cayuga’). Disking alone and application of glyphosate or paraquat alone did not satisfactorily control all weeds. However, the combination of a herbicide and disking controlled weeds enough to allow excellent establishment of alfalfa. In the year after establishment, the first cutting yields from the better combination treatments ranged from 3000 to 4400 kg/ha, which is normal for mid- to late-summer plantings in the region. Glyphosate was better than paraquat for control of grass weeds. Paraquat approached glyphosate in effectiveness when a supplemental disking treatment was added. Disking was as effective as the herbicide treatments for control of yellow nutsedge but not for control of broadleaf or annual grass weeds.
Germination of Seed of Dwarf Spikerush (Eleocharis coloradoensis)
Authors: Yeo R. R. , Dow R. J.
Published: May 2019

Treatments that enhanced the germination of dormant seed of dwarf spikerush [Eleocharis coloradoensis (Britt.) Gilly] the most were chilling seed at 2 C for 3 months and then scarifying with sodium hypochlorite, scarifying seed and then chilling wet seed at 7 C for 3 months, or chilling wet seed at 2 C for 24 months. Percentage of germination for these treatments were 58, 56, and 65%, respectively. Scarifying seed with sodium hypochlorite after they had been chilled wet for 12 to 24 months at 2 C reduced germination. Other treatments that significantly enhanced germination were chilling seed wet for 4 months at 2 C, scarifying dry-stored seed with a 5.25% solution of sodium hypochlorite for 10 h, and soaking seed in concentrated hydrochloric acid for 24 min. These latter treatments resulted in germination percentages of 35, 33, and 35, respectively. Eighty percent of the viable seed usually germinated within 10 days, and when germination was poor, seed lacked embryos or were empty. Dormancy appeared to be due to an impermeable seed coat and not to a germination inhibitor.
Control of an Oak(Quercus)Complex with Herbicide Granules
Authors: Meyer R. E. , Bovey R. W. , Baur J. R.
Published: May 2019

Granule, and in some cases, tablet and ball formulations of bromacil (5-bromo-3-sec-butyl-6-methyluracil), dicamba (3,6-dichloro-o-anisic acid), picloram (4-amino-3,5,6-trichloropicolinic acid), karbutilate [tert-butylcarbamic acid ester with 3(m-hydroxyphenyl)-1,1-dimethylurea], and tebuthiuron {N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethyl urea} were applied to three areas within 30 km of College Station in the Claypan Resource area of Texas. Woody species growing in the area included blackjack oak(Quercus marilandicaMuenchh.), post oak(Quercus stellataWangenh.), yaupon(Ilex vomitoriaAit.), winged elm(Ulmus alataMichx.), white ash(Fraxinus americanaL.), mockernut hickory(Carya tomentosaNutt.), and tree huckleberry(Vaccinium arboreumMarsh.). Granules were applied either broadcast or in rows at several intervals. Tebuthiuron was the most effective herbicide on oaks, winged elm, and white ash. Tebuthiuron and picloram were equally and most effective on yaupon, mockernut hickory, and tree huckleberry. Tebuthiuron + picloram at 2.2 + 2.2 kg/ha was the most effective herbicide treatment on huckleberry. However, a mixture of tebuthiuron + picloram (1:1 w/w) was usually no more effective than the same rate of tebuthiuron in the mixture applied alone. Tablet and ball formulations of karbutilate and tablet formulations of tebuthiuron were generally equally as effective as granules. Applications of picloram and tebuthiuron granules in rows 1.8, 3.0, 4.6, or 6.1 m apart gave control equal to broadcast applications except for picloram on yaupon. On yaupon all row spacing treatments of picloram were less effective than the broadcast treatment, whereas with tebuthiuron the 6.1-m spacing was least effective. Picloram and tebuthiuron granules applied in rows, approximately at 1.8-m intervals with a tractor, were as effective as granules applied by hand in straight rows.
Responses of Six Morningglory(Ipomoea)Species to Bentazon
Authors: McClelland M. R. , Oliver L. R. , Mathis W. D. , Frans R. E.
Published: May 2019

Field and greenhouse tests were conducted from 1974 to 1976 to determine the most effective rate and number of applications of bentazon [3-isopropyl-1H-2,1,3-benzothiadiazin-(4)3H-one 2,2-dioxide] for the control of six morningglory(Ipomoea)species. Growth chamber studies were conducted to determine photosynthesisrespiration equilibrium points (PRE-points) on two morningglory species. These units were used to measure the duration of the phytotoxic effect of bentazon on these morningglories from both single and repeat applications. Declining PRE-points indicated declining bentazon toxic activity within the plant. A treatment of two applications of bentazon at 0.84 kg/ha applied at a 4-day interval beginning with 2-week-old morningglory plants was optimal for maintaining a high PRE-point level. In field and greenhouse studies the greatest toxicity, regardless of morningglory species, occurred with bentazon at 0.84 or 1.12 kg/ha applied at 14 days and repeated at 28 days after emergence and 0.56 kg/ha applied three times with the first application made 14 days after emergence. Differences in susceptibility of the individual species indicated the importance of proper species identification before bentazon applications.
Survival of Hydrilla (Hydrilla verticillata) Plants and Propagules After Removal From the Aquatic Habitat
Authors: Basiouny F. M. , Haller W. T. , Garrard L. A.
Published: May 2019

Survival of hydrilla (Hydrilla verticillata Royle) plants and propagules after removal from water and desiccation under controlled conditions were studied. Both apical and sub-apical sections of hydrilla plants were physiologically alive after drying for 16 h at 30 C and 40% relative humidity. Tubers survived drying conditions longer than turions. There was 16.7% sprouting in tubers that had been dried for 64 h, while percent sprouting of turions decreased sharply as the drying period increased from 0 to 8 h.
Interference of Pale Smartweed (Polygonum lapathifolium) with Cabbage (Brassica oleracea)
Authors: Horng Liang-Chi
Published: May 2019

The competitive effects of pale smartweed (Polygonum lapathifoliumL.) were studied on cabbage (Brassica oleraceaL. ‘K-Y’) which was transplanted into rice (Oryza sativaL.) fields either 3 to 12 days before or 5 days after rice was harvested. Competitive effects were determined at weekly intervals from the time beds were formed around the cabbage at 5 days after rice harvest. Where cabbage was transplanted before rice harvest, at a time before pale smartweed germination, cabbage yields were reduced when weeds were allowed to grow for more than 4 weeks from the time the beds were formed. Where cabbage was transplanted at 5 days after the rice was harvested at a time when parts of pale smartweed had emerged, cabbage yields were reduced when weeds were allowed to grow for only 2 or more weeks after the beds were formed. Also, where weeds were removed at the beginning but allowed to grow at a later date, yield was reduced when cabbage was not kept weed-free for a minimum of 4 weeks.
Introduction
Authors: Zimdahl R. L.
Published: May 2019

The first WSSA international session was organized by the society's International Affairs Committee with approval of the Board of Directors. The committee's objective was to present a broad view of weed research in the world. To do this, we invited participants who were presently, or who had been, on the staff of one of the international agricultural research centers. We also invited Dr. M. Horowitz, the WSSA Honorary Member for 1979, to present information on his work in Israel.
Weed Management in Asian Vegetable Cropping Systems
Authors: William R. D. , Chiang M. Y.
Published: May 2019

In tropical and subtemperate regions of the world, farmers plant vegetables and other crops in a vast array of cropping systems that often involve more than one crop being grown on the same parcel of land in a year. Weed communities within each cropping system shift depending on physical and climatic factors and the specific crop and weed management practices employed. Modern weed management strategies involve combinations of crop production practices and specific weed control technologies intended to reduce weed competition, thereby shifting the competitive balance in favor of the crop. Weed research and, training efforts, therefore, must focus on the entire cropping system with emphasis on year-round and multi-year management of weed communities.
Weed Research in Israel
Authors: Horowitz Menashe
Published: May 2019

In Israel, an intensive modern agriculture has developed under difficult ecological constraints. The climate is characterized by two distinct seasons – a cool, rainy winter and a hot, dry summer. In winter, there are often temporary excesses of rain, causing erosion and preventing regular cultivation of fields; and in summer the soil dries out, and intensive cropping is only possible with irrigation. However, water is scarce and rationed directly by maximizing irrigation efficiency, and indirectly by controlling weeds, which compete for soil moisture.
Integrating Weed Biological Control Agents into a Pest-Management Program
Authors: Andres Lloyd A.
Published: May 2019

Little effort has been directed toward integrating biological control; that is, the use of living natural enemies to control weeds, with more conventional weed control practices. The usual focus of biological control has been on the introduction of weed insects and pathogens from foreign areas to control naturalized range, pasture, and/or aquatic weeds, principally single species that had become dominant over a plant community. The released natural enemies were allowed to reach their own balance with the target weed without added assistance. As economic and environmental perspectives change along with our knowledge and technological capability, however, it becomes worthwhile to review periodically if and how biological control might be integrated with other farming practices. Because my biological control experience has centered on the use of weed-feeding insects, this discussion will focus on methods of enhancing and integrating insect impact on weeds with other weed-control activities.
Pathogens as Mechanisms for Integrated Weed Management
Authors: Quimby P. C. , Walker H. L.
Published: May 2019

A need exists to manage or manipulate plant pathogens for biocontrol of weeds in row crops. Many weed species remain refractory to conventional weed-control technology. Some of these weeds occur in the same families as important crops and are resistant or tolerant to many of the herbicides that are applied for weed control within those crops. Preemergence treatments are needed for some weed species for which only postemergence treatments are now available. The cost of controlling some weeds is so prohibitive that many farmers will not spend the necessary money; therefore, more economical control is needed.
Moisture Stress and Hydration-Dehydration Effects on Hemp Sesbania (Sesbania exaltata) Seed Germination
Authors: Williams Robert D.
Published: May 2019

Increased osmotic potential from 0 to −14 bars decreased the moisture uptake and germination of mechanically scarified hemp sesbania [Sesbania exaltata(Raf.) Cory] seed. Germination percentage for osmotic potential of 0, −2, −4, −6, and −8 bars was 86%, 86%, 70%, 19%, and 1%, respectively. This response to moisture stress was modified by imbibition, or hydration-dehydration, of the seed prior to the moisture stress. Imbibing the seed for as little as 2 h significantly increased its subsequent germination against moisture stress. One hydration-dehydration cycle had little or no effect on germination, but as the number of cycles increased, the germination percentage decreased. Prolonged hydration of 3 and 7 days followed by dehydration greatly reduced subsequent seed germination.
Control of Weeds in Cranberries (Vaccinium macrocarpon) with Glyphosate and Terbacil
Authors: Shawa Azmi Y.
Published: May 2019

Glyphosate [N-(phosphonomethyl)glycine] applied to cranberry (Vaccinium macrocarponAit.) as a spray at 4 kg/ha in March controlled aster (Aster subspicatusNees) 77 to 87%. Glyphosate swab treatment with 6% solution in July or August, 1978 controlled spirea (Spiraea douglasii C.) 90%. A single application of terbacil (3-tert-butyl-5-chloro-6-methyluracil) in April, 1976 at 2 kg/ha controlled inflated rush (Carex vesicariaL.) 70% for 3 yr. Phytotoxicity was not observed on ‘McFarlin’ cranberry vines from any of these glyphosate or terbacil applications. Phytotoxicity did result from April, July, or August spray applications of glyphosate. Swab treatments did not cause any injury to cranberry.
Effect of 2,4-D on the Hydrolysis of Diclofop-Methyl in Wild Oat (Avena fatua)
Authors: Hill B. D. , Todd B. G. , Stobbe E. H.
Published: May 2019

The basis for 2,4-D [(2,4-dichlorophenoxy)acetic acid] antagonism of diclofop-methyl {methyl 2-[4-(2,4-dichlorophenoxy) phenoxy] propanoate} toxicity to wild oat (Avena fatuaL.) was investigated by studying changes in the metabolism of diclofop-methyl in vitro. An esterase from wild oat, which hydrolyzes diclofop-methyl to the acid diclofop, was extracted, partially purified, and the reaction characterized. The rate of hydrolysis of14C-diclofop-methyl was 0.14 ηmoles/2 h at standard assay conditions of 0.25 mg lyophilized enzyme preparation (19.6% protein) in 0.1 ml phosphate buffer (0.1 M, pH 7.0), substrate 5 μM. The addition of 2,4-D to this reaction did not inhibit14C-diclofop formation. Higher levels of 2,4-D stimulated enzymic hydrolysis.14C-diclofop-methyl was rapidly metabolized to14C-diclofop and polar14C-conjugates when vacuum-infiltrated into wild oat leaf segments. The addition of 2,4-D caused small increases in the rates of both14C-diclofop-methyl de-esterification and14C-diclofop conjugation. It is concluded that 2,4-D does not inhibit the in vitro de-esterification of diclofop-methyl.
Influence of Soil Temperature and Soil Moisture on Green Foxtail (Setaria viridis) Establishment in Wheat (Triticum aestivum)
Authors: Blackshaw R. E. , Stobbe E. H. , Shaykewich C. F. , Woodbury W.
Published: May 2019

The rate and final germination percentage and emergence of green foxtail [Setaria viridis(L.) Beauv.] was found to be very dependent on the soil temperature and moisture conditions at the time of seeding. In contrast, the germination and emergence of wheat (Triticum aestivumL. ‘Sinton’) was only slightly affected over the temperature and moisture range of the study. In laboratory studies, a temperature decrease from 20 to 15 C caused a 53- and 12-h delay in the time to reach 50% germination of green foxtail and wheat, respectively. Soil moisture was found to have a greater effect than soil temperature on green foxtail germination. At −5.3 bars water potential, the final germination percentage of green foxtail was less than at the higher water potentials. A further decrease in the water potential to −6.5 bars effectively reduced green foxtail germination to zero. Wheat germination was delayed only slightly, and the final germination percentage remained unchanged over the range of 0 to −15.3 bars water potential. In field studies, a soil temperature decrease from 22 to 14 C caused a 6-day delay in the time of 50% emergence of green foxtail, and the emergence of wheat was delayed only 1 day by a similar decrease in temperature. Field studies showed that when the soil was moist (0 to −4 bars) and soil temperatures were warm (20 to 25 C), green foxtail emerged within a few days of wheat. However, when the soil was dry (-4.0 to −6.5 bars) and soil temperatures were low (15 to 20 C), green foxtail emerged 7 to 14 days after wheat. The intensity of green foxtail competition was greater when green foxtail emerged within a few days of wheat than when green foxtail emerged 2 weeks after wheat.
Influence of Ammonium Thiocyanate on Scorching and Control of Bracken (Pteridium aquilinum) by Amitrole
Authors: Cook G. T. , Stephen N. H. , Duncan H. J.
Published: May 2019

The field performance of amitrole (3-amino-s-triazole) formulations containing a number of additives was tested on bracken [Pteridium aquilinum (L.) Kuhn var. aquilinum]. All formulations that did not contain thiocyanate produced severe foliar scorching within 72 h of spraying. The following season, control was relatively poor (63 to 77% reductions in frond density). The formulation of amitrole with sodium iodide produced particularly severe scorching followed by a nonsignificant reduction in frond density (2%) the following season. Formulations containing ammonium thiocyanate (molar ratios of 1:0.5, 1:0.75, 1:1, and 1:1.25 amitrole:ammonium thiocyanate) greatly reduced this foliar scorching, and control the following season was of the order of 94 to 97% in all cases. Translocation was proposed as being the limiting factor in control, ammonium thiocyanate increasing translocation by preventing scorching and hence decreasing decomposition in the foliage. To investigate scorching further, a bioassay, which consisted of floating bracken leaflets on amitrole solutions, was developed. The commercial 1:1 molar ratio of amitrole:ammonium thiocyanate may not be optimum for all conditions. Other additives were tested and cyanide and hexacyanoferrate (II) were found to be very active scorch inhibitors.
Herbicide Dispersal Patterns: HI. as a Function of Formulation
Authors: Hess F. D. , Bayer D. E. , Falk R. H.
Published: May 2019

The distribution patterns of several herbicide formulations sprayed on adaxial leaf surfaces were determined using scanning electron microscopy coupled with cathodoluminescence and x-ray microanalysis. The sodium and amine salts of MCPA {[(4-chloro-o-tolyl) oxy] acetic acid} sprayed on sugar beet (Beta vulgarisL.) leaves appeared as discrete deposits above the anticlinal cell walls that represented the location of spray drops that adhered to the leaf. When the sodium salt was applied to bermudagrass [Cynodon dactylon(L.) Pers.], the pattern of distribution was the same; however, each deposit was significantly smaller. The iso-octyl ester of MCPA coalesced into numerous, small, thick deposits on the cuticle of sugar beet leaves. The distribution of a wettable powder formulation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino-s-triazine] appeared as uniform deposits over the anticlinal and periclinal cell walls that represented the location of aqueous spray drops after application. When a flowable formulation of atrazine was applied, there was a significant preferential accumulation of the herbicide at the edges of the separate deposits. One commercial formulation of propanil (3′,4′-dichloropropionanilide) yielded deposits that were crystalline, one that was partially crystalline, and one that was noncrystalline.
Johnsongrass (Sorghum halepense) Control in Soybeans (Glycine max) with Metriflufen
Authors: Rogers N. K. , Talbert R. E. , Oliver L. R.
Published: May 2019

Field experiments were conducted in 1977 and 1978 to determine susceptibility of rhizome johnsongrass [Sorghum halepense(L.) Pers.] to metriflufen3{2-[4-(4-trifluoromethylphenoxy) phenoxy] propanoic acid, methyl ester} applied as preplant-incorporated, preemergence, or postemergence treatments. Rates of metriflufen applied preplant incorporated and preemergence were 1.12, 2.24, and 3.36 kg/ha. Postemergence treatments consisted of 0.56, 1.12, and 1.68 kg/ha of metriflufen plus a non-ionic polyethylene glycol alkyl ester, each applied to johnsongrass at growth stages of 30 to 38 cm, 60 to 75 cm, and heading. Johnsongrass control increased with each increase in rate of soil-applied metriflufen with no differences in control between preplant incorporated and preemergence treatments. Johnsongrass density was reduced by increased rates of metriflufen, and 1978 soil-applied treatments reduced densities by 62%. Preplant-incorporated and preemergence applications of 3.36 kg/ha of metriflufen resulted in higher soybean yields than did the two lower rates. Results from treatments with trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) were similar to those with metriflufen at the same rate. Metriflufen applied to 30-to 38-cm johnsongrass reduced stands by 60% in 1978, but stands increased by 51 and 71% in plots treated at the 60- to 75-cm or heading stages of growth. Soybean tolerance to postemergence applications of metriflufen was excellent for all stages of growth and rates of metriflufen.
Chlorophyll Fluorescence Assay for the Determination of Triazine Resistance
Authors: Ahrens W. H. , Arntzen C. J. , Stoller E. W.
Published: May 2019

A procedure is described for the rapid analysis of leaf samples to determine triazine resistance. The technique uses a commercially available fluorometer and is based upon the fact that photosynthesis-inhibiting herbicides increase chlorophyll fluorescence (because of dissipation of absorbed radiant energy in the absence of useful photochemistry). Resistant and susceptible biotypes of six weed species were assayed. Fluorescence of susceptible leaf sections increased dramatically over a 1- to 3-h exposure to atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine], but resistant leaf sections showed no fluorescence increase. Substantial fluorescence increases of both resistant and susceptible leaf sections were induced by diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea]. In the absence of herbicides, fluorescence was higher in resistant than in susceptible leaf sections, suggesting that the resistant biotypes are less efficient photosynthetically. Fluorescence analysis was used to characterize atrazine inhibition of photosynthesis in leaf sections of three crop species. Differences in atrazine-induced fluorescence between crop lines were relatively small and were not well correlated with atrazine tolerance. The fluorometer is a convenient device for monitoring photosynthesis inhibition, however, and could be useful in detecting plants having resistance to photosynthesis-inhibiting herbicides.
Economic Consequences of Bans on Corn (Zea mays) and Soybean (Glycine max) Herbicides Commonly used on Indiana Farms
Authors: Cashman C. M. , Martin M. A. , McCarl B. A.
Published: May 2019

The short-run economic consequences of bans on herbicides commonly applied to corn (Zea maysL.) and soybeans [Glycine max(L.) Merr.] on a typical Indiana farm were analyzed. A dinitroaniline ban reduced soybean yields and net farm income 17 and 32%, respectively. A triazine ban reduced corn and soybean yields 3 and 20%, respectively, and net farm income by 38%. A simultaneous ban on all dinitroaniline, triazine, and amide herbicides reduced corn and soybean yields 14 and 17%, respectively, and net farm income by 65%. Harvest delays attributable to less effective weed control resulted in a loss in efficiency, yields, and profits, and increased machinery and labor requirements. Hence, herbicide bans under typical Indiana conditions would inflict substantial, short-run economic losses on individual farmers. This study did not measure any potential public benefits or costs of herbicide bans, however.