bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Tolerance of Soybean (Glycine max) to Metribuzin
Authors: Buzzell Richard I. , Hamill Allan S.
Published: March 2018

Backcross-derived isolines of soybean [Glycine max(L.) Merr.] cultivars with and without theRps1-kgene for resistance to Phytophthora rot (Pythopthora megaspermaf. sp.glycinea) were grown in hydroponic culture with and without metribuzin [4-amino-6-(1,1-dimethylethyl)-3-3(methylthio)-1,2,4-triazin-5(4H)-one] added at 0.15 mg L−1. A marked tolerance to metribuzin was associated withRps1-kpossibly from an allele at theHm/hmlocus which is known to be linked closely with theRps1locus. This improved tolerance could reduce the occurrence of injury from metribuzin applications.
Wild Mustard,Sinapis arvensis, Control in Common Buckwheat,Fagopyrum esculentum, with Desmedipham and Fluorochloridone
Authors: Friesen George H.
Published: March 2018

Desmedipham applied at 0.5 kg ai/ha at the 4-leaf stage of common buckwheat controlled wild mustard over 90%. Desmedipham at 1.0 kg/ha at the 2- and 6-leaf stages also controlled wild mustard approximately 90%, at least in 1985, but significantly injured the crop. Fluorochloridone controlled wild mustard over 90% when applied preplant incorporated at 1.0 kg ai/ha or preemergence at 0.28 to 0.56 kg/ha. Fluorochloridone applied postemergence at 0.10 to 0.20 kg/ha also controlled wild mustard over 90% but injured common buckwheat by 41 to 57%.
Evaluating Groundwater Contamination Potential from herbicide use
Authors: Leonard Ralph A. , Knisel Walter G.
Published: March 2018

Potential herbicide loadings to groundwater are determined by soil, chemical, management, and climatic factors. Several simple assessment procedures to rank pesticides according to their potential impact on groundwater are available. Most of these procedures are not specific to any climatic region, cropping practice, or soil. Using a continuous simulation model, GLEAMS (Groundwater Loading Effects of Agricultural Management Systems), to assess potential herbicide leaching allows more condition-specific assessment. Simple relationships for relative comparisons in a specific soil/climatic setting were developed by relating simulated 50-yr mean leaching losses to the herbicide half-life/Koc ratio. Other criteria of herbicide leaching potential such as 50-yr maxima or other values based on probability distributions could be used. Although differences in soils were demonstrated in this exercise, the same procedures could be applied to different management systems.
Weed Thresholds in Southern U.S. Rice,Oryza sativa
Authors: Smith Roy J.
Published: March 2018

Knowledge of interference thresholds, biology, and growth habits of weeds of rice is essential to implement timely, effective, economical weed control technology for profitable rice production. Regression analyses were used to determine threshold levels for weed densities and durations of interference for major weeds of rice. Weed threshold information for individual species or combinations of species can be used to develop models for initiating control inputs and determining their costs and returns. Among the grass weeds in density experiments, red rice reduced rice grain yields the most followed by barnyardgrass, beared sprangletop, and broadleaf signalgrass. Among broadleaf/aquatic weeds in density experiments, hemp sesbania reduced rice grain yields the most followed by northern jointvetch, ducksalad, spreading dayflower, and eclipta. Barnyardgrass, broadleaf signalgrass, and ducksalad interfered with rice the most during early season, whereas eclipta, hemp sesbania, northern jointvetch, red rice, and spreading dayflower caused greater interference during mid- to late-season.
Persistence of Sulfonylureas in Pullman Clay Loam
Authors: Wiese Allen F. , Wood Mark L. , Chenault E. Wayne
Published: March 2018

Persistence of chlorsulfuron and other sulfonylurea herbicides, measured by sorghum injury, was determined on a Pullman clay loam (fine, mixed, thermic family of Torrertic Paleustolls) with soil pH varying from 6.5 to 8.1 in a 3-yr winter wheat-sorghum-fallow crop rotation. As pH increased from 6.5 to 8.0, chlorsulfuron persistence increased greatly. With soil pH of 6.5, chlorsulfuron at 34 g ai/ha used on growing wheat did not injure sorghum planted 16 months later. If pH was 7.5 or above, chlorsulfuron persisted and injured sorghum planted within 25 months after herbicide application. Persistence of sulfometuron and metsulfuron was about the same as chlorsulfuron, all of which persisted longer than metribuzin applied at normal use rates. Four annual applications of chlorsulfuron at 71 g/ha did not accumulate when soil pH was 6.5.
Economic Control of Weeds in Wheat,Triticum aestivum
Authors: Gillespie Greg R. , Nalewaja John D.
Published: March 2018

Field experiments were conducted at two locations during 1984 and 1985 to determine how time of wild oats and wild mustard control influenced spring wheat yield and net economic return. Wheat yield and economic return were greatest when both weed species were controlled with diclofop plus bromoxynil at the 2-leaf wheat stage. Delaying the application of herbicides or controlling only wild oats with diclofop or only wild mustard with MCPA reduced wheat yield and economic benefit from the herbicide treatment. Wild oats and wild mustard competed equally for limiting growth factors in a greenhouse experiment.
Chloramben for Weed Control on Muck-grown Lettuce,Lactuca sativa, and Endive,Cichorium endivia
Authors: Gorski Stanley F. , Reiners Stephen , Hassell Richard
Published: March 2018

Chloramben effectively controlled weeds in lettuce and endive grown on muck soils better than thiobencarb and chlorpropham. Chloramben at 1.1 kg ai/ha controlled two weeds economically important on muck soils, livid amaranth and oakleaf goosefoot. Chloramben applied preemergence at 1.1 kg/ha and higher caused early stunting of lettuce which the lettuce outgrew by harvest. Field-seeded endive was stunted severely at these same rates, severely reducing yield. Transplants improved tolerance of all crops. Effective use rates on muck soils were 25% to 50% of those typically used on mineral soils.
A Nutrient Culture Technique to Measure Lettuce,Lactuca sativa, Sensitivity to Thiobencarb
Authors: Reiners Stephen , Gorski Stanley F.
Published: March 2018

A modified nutrient solution, used to study lettuce cultivar response to thiobencarb, provided an excellent medium for lettuce growth and is an alternative to other nutrient solutions. Leaf dry weight was inhibited 50% by 3- and 5-μM thiobencarb in ‘Dark Green Boston’ and ‘Great Lakes 366’, respectively, while ‘Bibb’, ‘Slobolt’ and ‘Valmaine’ responded intermediately. Growth inhibitions and herbicide injury symptoms, which included abnormal growth and stunted secondary leaves, were similar in both nutrient solution and soil assays. Due to its ease of preparation and elimination of the variability associated with soil assays, the nutrient solution may be considered a superior alternative to soil assays.
Seedling Volunteer Asparagus,Asparagus officinalis, Control with Herbicides
Authors: Boydston Rick A.
Published: March 2018

Diuron, fluorochloridone, hexazinone, metribuzin, norflurazon, oryzalin, prodiamine, simazine, and terbacil controlled seedling asparagus planted in sprinkler-irrigated plots similarly (>89%). In furrow-irrigated plots, cinmethylin, diuron, fluorochloridone, hexazinone, napropamide, oryzalin, and prodiamine provided similar control (>86%) of planted seedling asparagus. Herbicides with high water solubilities that depended upon root uptake for maximum activity tended to control seedling asparagus better in sprinkler-irrigated tests than in furrow-irrigated tests. Fluorochloridone, norflurazon, and prodiamine provided partial control of volunteer asparagus (48 to 84%) in an established stand of furrow-irrigated asparagus.
Analyzing Herbicide Interactions: A Statistical Treatment of Colby's Method
Authors: Flint Jerry L. , Cornelius Paul L. , Barrett Michael
Published: March 2018

A model and a proposed method for testing herbicide interactions were modified from an analysis of variance (ANOVA) model for a 2 by 2 factorial experiment. Statistical tests for either synergism, antagonism, or additivity of herbicide combinations were developed through transforming growth data to logarithms followed by significance tests of 2 by 2 contrasts of the form μii- μi0- μ0i+ μ00with respect to the log-transformed data. Using actual experimental data, heterogeneity of variance was less severe on the log scale compared to the original measurement scale. An expedient SAS(R)program for obtaining the desired significance tests was developed.
Roller Application of Clopyralid for Huisache,Acacia farnesiana, Control
Authors: Scifres Charles J. , Crane Richard A. , Koerth Ben H. , Flinn Robert C.
Published: March 2018

Experiments were conducted in south Texas from 1983 to 1987 to evaluate clopyralid for huisache control using a carpeted roller. Huisache control with clopyralid applied as broadcast sprays or with a carpeted roller generally equaled that from the same rates of picloram or of 1:1 mixtures of clopyralid plus picloram. Applications of herbicides in the fall generally were more effective than in the spring, regardless of application method. In most cases, the herbicides at 48 to 60 g ae/L fall applied with a carpeted roller killed 70% or more of the huisache. Herbicide efficacy was not reduced when all huisache top growth was removed within 1 week after roller application of a 1:1 mixture of clopyralid and picloram at 60 g ae/L. The treat-and-cut sequence should improve the quality of hay from huisache-infested pastures.
A Water-Spray System for Removing Seed from Soil
Authors: Kovach David A. , Thill Donald C. , Young Frank L.
Published: March 2018

A seed remover using a modified water-spray system was constructed to separate weed seeds rapidly and effectively from a silt loam soil A 1-kg soil sample can be washed through the seed remover in 6 min. Using a 500-μ mesh sieve, only 70% of small shepherdspurse seeds were recovered, while 100% of larger seeds of henbit, curly dock, wild oats, and downy brome were recovered. The modified seed remover system reduced the required man-hours by more than 50% compared to previous systems.
The Biology of Mediterranean Saltwort,Salsola vermiculata
Authors: Creager Richard A.
Published: March 2018

Mediterranean saltwort, a member of the family Chenopodiaceac, is a dominant perennial species in the Mediterranean arid zone. Propagation is by seed only, and those collected from an infestation in California were used for various germination studies. Seed with the persistent calyx removed germinated 2 to 4 days earlier than those with the calyx present. The germination percentage was also greater (82 vs 62% at Day 13) than seed with the calyx. Those seed stored at room temperature germinated less than seed stored in the refrigerator or freezer. Brown (mature) seed germinated earlier and more than green seed. Greenhouse-grown plants cut or burned off at the ground level failed to regrow. Plants cut at 1 cm or more above ground level regrew from side shoots. Mediterranean saltwort could become a serious noxious weed in areas of the United States that have a Mediterranean climate.
Russian Thistle,Salsola iberica, Control in Onion,Allium cepa
Authors: Cudney David W. , Orloff Steve B.
Published: March 2018

The effectiveness of oxyfluorfen and bromoxynil for Russian thistle control in onion was measured in a 2-yr study conducted in the high desert region of southern California. Oxyfluorfen, bromoxynil, or combinations of the two applied one at the 2-leaf growth stage of onion did not control Russian thistle. When a first application was followed 14 days later with a second herbicide application, a first application of oxyfluorfen plus bromoxynil was most effective. Oxyfluorfen applied alone as a second application was least effective, but bromoxynil alone plus oxyfluorfen improved control. Adding petroleum oil to oxyfluorfen plus bromoxynil improved Russian thistle control.
Enhanced Soil Degradation of Butylate and EPTC in Nebraska Fields
Authors: Roeth Fred W. , Wilson Robert G. , Martin Alex R. , Shea Patrick J.
Published: March 2018

A survey to determine the frequency and weed control impact of enhanced degradation of butylate or EPTC in field soils receiving repeat applications of these herbicides was conducted in a sugarbeet and three corn growing areas of Nebraska. All seven of the sugarbeet field soils exhibited enhanced EPTC degradation. In the corn areas, none of the 13 north central and southeast field soils displayed accelerated degradation; however, 10 of the 16 south central field soils did. In south central Nebraska, 60% and 45% of the surveyed growers were dissatisfied with weed control from butylate or EPTC in 1983 and 1984, respectively, compared to 24% and none in other survey areas. Enhanced herbicide degradation and the presence of shattercane were the main reasons for the disparity among areas.
Seasonal Variations in Jack Pine (Pinus banksiana)and White Spruce (Picea glauca)Tolerance to Glyphosate and Triclopyr
Authors: Willis R. G. , Stephenson G. R. , Fletcher R. A. , Prasad R.
Published: March 2018

Seasonal variations in tolerance of jack pine and white spruce to glyphosate and triclopyr were investigated in field and growthroom studies. Foliar injury was higher in both species following field applications of herbicides in July during periods of active growth than in September and October when the plants were not growing actively. Herbicides applied to trees in the growthroom 3 weeks after bud break caused greater injury than applications either before or 14 weeks after bud break. White spruce tolerated both glyphosate and triclopyr better than jack pine. Triclopyr injured both species more than glyphosate. Chemical analysis and electron micrographs showed that the cuticular wax deposition on both species was greater in field-grown trees than in growthroom-grown trees and was greater at 14 weeks after bud break than at 3 weeks. Increased wax deposition with time after bud break may reduce herbicide uptake and may account partially for the increased tolerance of both species to glyphosate and triclopyr.
Decision Criterion for Profitable Johnsongrass (Sorghum halepense) Management in Soybeans (Glycine max)
Authors: Roberts Roland K. , Hayes Robert M.
Published: March 2018

A decision criterion is presented for postemergence johnsongrass control in soybeans. Models derived from actual data describing the relationship between johnsongrass density (X) and soybean yield loss are used to develop the decision criterion for soybeans planted in 0.25- and 1-m row spacings. The yield loss equations are L1 = 424–424 exp (-0.023X2) for 0.25-m row spacing and L2 = 643-643 exp (−0.004X2) for 1-m row spacing. When combined with the cost of control (Px) and the expected price of soybeans (Py), these equations can be used to find the density thresholds where johnsongrass control becomes profitable. For the 0.25-m row spacing, this relationship was Px = Py [424–424 exp (−0.023X2) or more simply Px = Py L1, which equates the cost of control to the value of the soybean yield increase from control. The johnsongrass density (X) that satisfies this equality is the threshold (X*) above which control is profitable.
Response of Centipedegrass (Eremochloa ophiuroides) to Plant Growth Regulators and Frequency of Mowing
Authors: Johnson Billy J.
Published: March 2018

When centipedegrass was unmowed, seedhead suppression generally was better with imazethapyr than with mefluidide either alone or with flurprimidol, but these treatments were not effective for 8 weeks. In several instances, imazethapyr at 0.30 kg ai/ha and MH at 2.2 and 4.5 kg ai/ha severely injured (>30%) centipedegrass. Mowing weekly did not control seedhead development effectively, and none of the plant growth regulator plus mowing treatments effectively suppressed seedheads for 12 weeks. To effectively suppress seedhead production for 8 weeks, centipedegrass treated with mefluidide required mowing 3 weeks after treatment, while centipedegrass treated with imazethapyr or flurprimidol plus mefluidide required mowing at 3 and 6 weeks.
Metolachlor and Alachlor Persistence in Rice (Oryza sativa) Following Soybean (Glycine max)
Authors: Griffin James L. , Robinson John F.
Published: March 2018

Field studies were conducted for 3 yr to evaluate the persistence of metolachlor and alachlor applied to ‘Centennial’ soybean and to determine their residual effect on ‘Mars' rice. At labeled use rates of metolachlor at 2.8 kg ai/ha and alachlor at 3.9 kg ai/ha, soil residue levels in the fall 5 months after application on Crowley and Midland silt loam soils averaged 0.04 and 0.05 ppmw, respectively. Metolachlor fall soil residues averaged 3.5 times higher when applied at 5.6 and 11.2 kg/ha compared to 2.8 kg/ha, but residues for labeled and double rates of alachlor were similar. In the spring 9 months after herbicide application, soil residues averaged over years did not exceed 0.06 ppmw. The 3-yr rice yields were not affected by residual metolachlor or alachlor.
Quackgrass (Agropyron repens) Control in Birdsfood Trefoil (Lotus corniculatus) Seed Production
Authors: Linscott Dean L. , Vaughan Richard
Published: March 2018

Between 1982 and 1986, spring treatments of haloxyfop, fluazifop, and sethoxydim all applied at 400 g ai/ha alone and combined with dalapon at 3400 g ai/ha were evaluated for quackgrass control and subsequent effect on established birdsfoot trefoil seed production. Haloxyfop alone and combined with dalapon were superior to fluazifop or sethoxydim alone or mixed with dalapon for controlling quackgrass and other grass weeds. Birdsfoot trefoil seed yield averages over 3 yr were 310, 160, 150, and 180 kg/ha after treatment with haloxyfop, fluazifop, sethoxydim, and dalapon, respectively, compared to a control yield of 80 kg/ha. Yields were lower, 220 kg/ha, with combinations involving haloxyfop plus dalapon compared to haloxyfop alone.
Growing Weeds in Nonaerated Nutrient Solution
Authors: Andersen Robert N. , Ralston Donald F.
Published: March 2018

Velvetleaf, eastern black nightshade, wild mustard, common cocklebur, green foxtail, and yellow foxtail, grown for 4 weeks in nonaerated nutrient solution, developed satisfactorily compared to plants grown in soil. For experiments involving certain weed species grown in nutrient solution, aeration may be unnecessary.
Jimsonweed
Authors: Mitich Larry W.
Published: March 2018

Jimsonweed, Jamestown weed, datura, stramonium, thornapple, tolguacha. These are some of the more than a score of common English names used for jimsonweed (Datura stramonium L. #3 DATST), a cosmopolitan weed of worldwide distribution. The above names are those used most widely in the United States. Jimsonweed is a corruption of Jamestown weed, the name given the plant in colonial days because it first grew in and around Jamestown, VA (2). It had been brought from England as a medicinal plant. Boiled with hog's grease, jimsonweed made a healing salve for burns from “fire, water, boiling lead, gunpowder, and lightning” (2).
Response of Huisache (Acacia farnesiana) Seedlings to Herbicides Applied with a Model Carpeted Roller
Authors: Mayeux Herman S. , Bovey Rodney W.
Published: March 2018

Mortality of potted huisache seedlings averaged 87 to 100% 18 weeks after picloram or clopyralid was applied with a model carpeted roller at concentrations as low as 7.5 g ae/L. A 1:1 mixture of picloram and clopyralid was equally effective. Triclopyr was effective only when applied to small seedlings in the spring, and an ester was more effective than an amine formulation. A 1:1 mixture of clopyralid and triclopyr ester was intermediate in effectiveness between the two herbicides applied alone. Adding surfactant increased canopy reduction and plant mortality (P = 0.1 to 0.01), especially at lower herbicide concentrations.
Perennial Vine Control in Multiple Cropping Systems on a Clay Soil
Authors: Elmore C. Dennis , Heatherly Larry G. , Wesley Richard A.
Published: March 2018

An area of a shrink-swell clay soil (Tunica clay, Vertic Haplaquept) with an established population of redvine, trumpetcreeper, honeyvine milkweed, redberry moonseed, and maypop passionflower was treated with dicamba once in the fall of 1983. The effect on perennial vines was determined for the following 4 yr in three rotational cropping systems involving winter wheat, soybean, corn, and sorghum, all with and without irrigation. Dicamba reduced the population of perennial vines 80% over 4 yr. Redvine and trumpetcreeper, the first and second most abundant species, were reduced by over 83 and 76%, respectively. Yield of soybean increased 17% in 1985 and 1987 while corn yield increased 9% in 1986 with dicamba use. In 1984 no effects on crop yield were measured. This inconsistent crop yield reponse after dicamba treatment, even though perennial vines were suppressed, must be considered in evaluating the economics of using dicamba for perennial vine control.
Factors in Alachlor and Metolachlor Injury to Corn (Zea mays) Seedlings
Authors: Boldt L. D. , Barrett M.
Published: March 2018

Growth chamber experiments were conducted to determine if certain genetic, environmental, and chemical factors or their interactions promote chloroacetamide herbicide injury to corn seedlings. Greater chloroacetamide injury occurred with ‘Pioneer 3320’ than with ‘Pioneer 3780’ hybrid corn, with 15 C than with 30 C soil temperature, with soil moisture at 105% field capacity (FC) than at 75% FC, with alachlor than with metolachlor, and with a herbicide rate of 2.2 kg/ha than with 1.1 kg/ha. Covering the plant containers with clear plastic until seedling emergence caused alachlor to be more phytotoxic to corn than metolachlor. Most factors evaluated increased the injury to corn in an additive manner.
Interaction of Insects, Fungi, and Burial on Velvetleaf (Abutilon theophrasti) Seed Viability
Authors: Kremer Robert J. , Spencer Neal R.
Published: March 2018

A scentless plant bug feeds on velvetleaf seeds. Fungi, dominated by the generaFusariumandAlternaria, were isolated from insect-attacked seeds at levels related to insect density on the plants. The combined effects of insect feeding and fungal infection decreased seed germination. Burial of insect-attacked seeds in soil for 24 months reduced seed survival and increasedFusariuminfection. Decreases in velvetleaf seed viability and survival in soil caused by a seed-feeding insect and associated seed fungi suggests that subsequent infestations by velvetleaf can be decreased through integrated use of the two biological control agents.
Tolerance of Five Perennial Cool-Season Grasses to Fluazifop
Authors: Warren Stuart L. , Skroch Walter A. , Monaco Thomas J. , Shribbs John M.
Published: March 2018

Five perennial cool-season grasses: Kentucky bluegrass, creeping red fescue, tall fescue, orchardgrass, and perennial ryegrass were treated at the 2- to 3-leaf, 3- to 4-leaf, 4- to 6-leaf, and 6- to 7-leaf growth stages with four rates (0, 0.14, 0.28, and 0.56 kg ai/ha) of the butyl ester of fluazifop. Creeping red fescue was not injured by any rate at any growth stage. Reduction in shoot dry weight increased linearly with increasing fluazifop rate for the remaining four species, except for the 6- to 7-leaf stage in Kentucky bluegrass and the 4- to 6-leaf stage in tall fescue and perennial ryegrass. Significant differences between growth stages within each rate varied with species. In general, tolerance increased at the 4- to 6-leaf and 6- to 7-leaf growth stages.
Microfoil Boom Application of Picloram and 2,4-D for Leafy Spurge (Euphorbia esula) Control
Authors: Lym Rodney G.
Published: March 2018

Leafy spurge control with picloram and various 2,4-D formulations was evaluated to determine the optimum treatment combination and carrier volume for aerial application using a microfoil boom. Leafy spurge control was similar when the same herbicide treatments were applied at 94 and 47 L/ha but declined at 23 L/ha. Leafy spurge control was better when similar herbicide treatments were applied with a one-row microfoil nozzle boom compared to a two-row nozzle. Leafy spurge control 12 months after treatment tended to be better with picloram at 0.28 and 0.56 kg ae/ha applied with 2,4-D mixed amine compared to picloram plus 2,4-D dimethylamine or oil-soluble amine formulations during average growing conditions. However, picloram plus 2,4-D oil-soluble amine was the best formulation in dry conditions.
Factors Influencing Germination and Emergence of Florida Beggarweed (Desmodium tortuosum)
Authors: Cardina John , Hook James E.
Published: March 2018

Florida beggarweed germination in laboratory experiments was highest between 21 and 38 C and at osmotic potentials above −0.2 MPa, with complete germination inhibition below −0.8 MPa. Patterns of seedling emergence in the field corresponded to timing and size of rainfall events in relation to the time of soil disturbance. Smaller percentage total seasonal emergence was observed following large rainfall events where soil had not been disturbed compared with plots recently disturbed, and soil disturbance not followed by rainfall did not promote major weed flushes.
Interference of Soybean,Glycine max, Cultivars with Sicklepod,Cassia obtusifolia
Authors: James Krista L. , Banks Philip A. , Karnok Keith J.
Published: March 2018

Greenhouse and field experiments were conducted at Athens, GA, during 1984 and 1985 to evaluate the interference of several soybean cultivars with sicklepod. The 12 soybean cultivats evaluated in the field were commonly used from 1907 to the present. No correlation of soybean cultivar maturity group or date of introduction with interference on sicklepod was observed. ‘Essex’ and ‘Bragg’ soybean reduced sicklepod dry weight in the field; however, only Essex was unaffected by sicklepod. In the greenhouse experiments, root and shoot growth of sicklepod was less than the cultivars ‘CNS', ‘Peking’, and ‘Forrest’. Sicklepod produced the least above- and below-ground growth while ‘CNS' produced the most of the three cultivars. When grown together, the combined total root growth of each cultivar plus sicklepod was less than calculated expected values. The genetic development of soybean cultivars with improved tolerance to sicklepod infestations possibly could reduce weed control inputs.
Herbicides for Killing Tall Fescue (Festuca arundinacea) Infected With Fescue Endophyte (Acremonium coenophialum)
Authors: Smith Albert E.
Published: March 2018

The importance of tall fescue as a pasture grass is diminished when infected with the fescue endophyte. The availability of fungus-free seed has necessitated the development of systems to kill the infected sod before interseeding fungus-free seed. Field studies were conducted to evaluate the response of fescue sod to foliar-applied herbicides as single and sequential applications during the fall and spring. Sequential applications of paraquat at 0.14, 0.28, and 0.56 kg ai/ha in September and October and glyphosate at 0.84 and 1.7 kg/ha applied as single or sequential applications in September and October resulted in more than 90% kill of the tall fescue sod. Spring treatments of paraquat and glyphosate were less effective than those applied in the fall. Dalapon, fluazifop-P, HOE-39866 [glufosinate (proposed name)], sethoxydim, and simazine did not effectively kill the sod.
Rice (Oryza sativa) Response to Imazaquin Residues in a Soybean (Glycine max) and Rice Rotation
Authors: Helms Ronnie S. , Tripp Timothy N. , Smith Roy J. , Baldwin Ford L. , Hackworth Max
Published: March 2018

Nine field experiments were conducted from 1984 through 1988 to determine the effect on rice of imazaquin applied to soybeans the previous growing season. Imazaquin was applied preplant incorporated, preemergence, or postemergence at rates ranging from 70 to 560 g ai/ha. ‘Bond’, ‘Lemont’, ‘Mars', ‘Newbonnet’, and ‘Tebonnet’ rice were planted the following year. Across all locations, years, cultivars, soil series, methods of application, and imazaquin rates, rice injury symptoms were not observed, and rice grain yields were not reduced by imazaquin residues.
Imazethapyr for Weed Control in Soybean (Glycine max)
Authors: Cantwell John R. , Liebl Rex A. , Slife Fred W.
Published: March 2018

Imazethapyr at 0.05 to 0.14 kg ai/ha applied preplant incorporated, preemergence, and postemergence was evaluated alone and with complementary herbicides in the field for weed control in soybean. Imazethapyr controlled 90% or more smooth pigweed regardless of application method or herbicide rate. Imazethapyr at 0.05 kg/ha controlled jimsonweed 30% better postemergence compared to soil applications. Imazethapyr at 0.10 kg/ha controlled 90% or more velvetleaf regardless of application method. The addition of alachlor to soil-applied imazethapyr enhanced giant foxtail, jimsonweed, and velvetleaf control. Adding acifluorfen or bentazon to postemergence imazethapyr antagonized weed control. Adding sethoxydim to postemergence imazethapyr was not beneficial.
Propanil Plus Tridiphane for Barnyardgrass (Echinochloa crus-galli) Control in Rice (Oryza sativa)
Authors: Street Joe E. , Snipes Charles E.
Published: March 2018

Field experiments were conducted from 1983 through 1985 to evaluate the influence of tridiphane at 0.3, 0.6, 1.1, and 2.2 kg ai/ha when tank mixed with propanil at 2.2 or 3.4 kg ai/ha on control of 3- to 4-leaf or 4- to 6-leaf barnyardgrass in rice. Tridiphane at 0.6 kg/ha or greater tank mixed with propanil at 2.2 or 3.4 kg/ha enhanced control of 3- to 4-leaf barnyardgrass compared to propanil applied alone at 3.4 kg/ha. Rates of tridiphane at 1.1 kg/ha or greater plus propanil at 3.4 kg/ha were necessary to control 4- to 6-leaf barnyardgrass. ‘Starbonnet’ rice injury was minimal for all treatments.
Applying Herbicides Over Snow to Control Weeds in Winter Wheat (Triticum aestivum)
Authors: Dewey Steven A. , Asghari Jafar , Tindall Terry A.
Published: March 2018

Chlorsulfuron at 0.018 kg ai/ha, metsulfuron at 0.0045 kg ai/ha, and 2,4-D at 1.1 kg ae/ha plus dicamba at 0.28 kg ae/ha were applied over snow-covered winter wheat to study the feasibility of combining herbicides with a graphite snow-removal treatment. Chlorsulfuron or metsulfuron applied on snow effectively controlled annual broadleaf weeds when tank mixed with urea ammonium nitrate (UAN) at 28 kg N/ha and graphite powder at 20 kg/ha. Over-snow treatments of 2,4-D plus dicamba plus UAN did not control weeds. There was no antagonism or synergism among herbicides, UAN, or graphite.
Stipa clandestina: New Weed Threat on Southwestern Rangelands
Authors: Barkworth Mary E. , Valdes-Reyna Jesús , Landers Roger Q.
Published: March 2018

Stipa clandestina Hackel, a native of northern Mexico, has been found in Texas and may become a serious weed problem for range managers in the southwest. Its sharply pointed leaves and tussock-forming habit make it unpalatable to cattle, but in Mexico it tends to increase with heavy grazing or disturbance. Actively growing plants can be killed by applying a foliar spray of either glyphosate or hexazinone.
Effect of DPX-V9360 and Terbufos on Field and Sweet Corn (Zea mays) Under Three Environments
Authors: Morton Cathy A. , Harvey R. Gordon , Kells James J. , Lueschen William E. , Fritz Vincent A.
Published: March 2018

Field studies were conducted in Michigan, Minnesota, and Wisconsin to explore interactions among DPX-V9360 herbicide applied postemergence, terbufos insecticide applied as an in-furrow treatment, and the environment. Field corn (‘Pioneer 3751’) and sweet corn (‘Jubilee’) were planted with and without an in-furrow application of terbufos. DPX-V9360 was applied postemergence when the corn was in the 4- to 6-leaf stage at 0, 35, 70, 140, and 280 g ai ha-1with nonionic surfactant and 28% N fertilizer solution. Crop response to DPX-V9360 was similar at all three locations, varying only in magnitude of injury. Crop injury was greater with Jubilee sweet corn than with Pioneer 3751 field corn. Injury to both hybrids increased as DPX-V9360 application rate increased. Application of terbufos increased injury from DPX-V9360 to both hybrids. Significant yield reduction did not occur with either hybrid when DPX-V9360 was applied at rates of 140 g ha-1or less and no terbufos was applied.
Preemergence Velvetleaf (Abutilon theophrasti) Control in Cotton (Gossypium hirsutum)
Authors: Snipes Charles E.
Published: March 2018

Experiments were conducted from 1987 through 1989 to determine the most effective and consistent control of velvetleaf in cotton with soil-applied herbicides. Norflurazon was applied at 1.1 or 1.7 kg ha-1either preplant (PPI) or preemergence (PRE) or by splitting these rates and applying half PPI and the other half PRE. All methods of norflurazon application were compared with and without a PRE application of diuron at 1.1 kg ha-1. The most consistent control was achieved with PPI norflurazon at either 1.1 or 1.7 kg ha-1followed by diuron. In 1988, crop injury at 2 wk varied and was 29% or greater for preemergence norflurazon tank-mixed with diuron.
Florida Beggarweed (Desmodium tortuosum) Growth and Development in Peanuts (Arachis hypogaea)
Authors: Cardina John , Brecke Barry J.
Published: March 2018

Temporal changes in factors that contribute to the competitiveness of Florida beggarweed in peanuts were studied in 1986 and 1987. Florida beggarweed leaves were unifoliolate to the ninth node and trifoliolate thereafter. Peanuts grew taller than Florida beggarweed until the R-3 stage of peanuts, after which Florida beggarweed height increased logarithmically. Florida beggarweed branching was suppressed by the peanut canopy until the weed overtopped the peanuts. Florida beggarweed dry weight was reduced 80% by peanuts compared with Florida beggarweed grown alone. Peanuts reduced Florida beggarweed leaf area and canopy area. Percent light attenuation as a function of Florida beggarweed canopy area was described by the equation Y = lnX/25.5. Peanut yields in 60 cm of row on either side of a single Florida beggarweed plant were reduced 19%.
Clopyralid Influences Rotational Crops
Authors: Thorsness Kevin B. , Messersmith Calvin G.
Published: March 2018

Field research was conducted at Fargo, Langdon, and Prosper, ND to determine carryover of clopyralid applied at 70 to 560 g ae ha-1 in soil as indicated by response of crops planted 1 yr after application. Flax, potato, and safflower growth at Fargo were not affected by clopyralid residues. At Fargo, soybean height, stand, and yield were reduced by residues from clopyralid at 560 g ha-1, and sunflower heads ha-1 and yield were reduced by residues from clopyralid at 280 and 560 g ha-1 and 560 g ha-1, respectively. Potato and sunflower at Langdon and Prosper and lentil at Langdon were not affected by clopyralid residues. Soybean yield at Prosper was not affected by clopyralid residues, but plant height was reduced by residues from clopyralid at 280 and 560 g ha-1. These results indicate that residues from clopyralid applied at labeled cropland rates, of 280 g ha-1 or less, in silty clay, clay loam, and silty clay loam soils in North Dakota probably will not adversely affect the dicot crops tested in these experiments planted 11 mo or more after application.
Effect of Imazaquin and Chlorimuron Plus Metribuzin on Sicklepod (Cassia obtusifolia) Interference in Soybean (Glycine max)
Authors: Shaw David R. , Wixson Marshall B. , Smith Clyde A.
Published: March 2018

Three experiments evaluated sicklepod interference with soybean with and without preplant incorporated applications of chlorimuron plus metribuzin or imazaquin. Sicklepod density, weed-free period, and weedy period were examined. In the absence of herbicides, soybean seed yield was reduced with 2 sicklepod plants row m-1, whereas 8 plants row m-1were necessary to reduce yield when herbicides were used. Herbicide use also increased soybean yield at higher sicklepod densities. Chlorimuron plus metribuzin reduced sicklepod dry matter at 8 plants row m-1. To maintain soybean yield, a weed-free period of 4 wk after emergence was required, regardless of treatment. Both herbicide treatments resulted in increased soybean yield at the zero and two wk weed-free periods; however, they did not affect soybean yield when the weed-free period was 4 wk or more. Imazaquin reduced sicklepod density when plots were left weedy full-season, and further reductions were noted with chlorimuron plus metribuzin. A sicklepod weedy interval of 8 wk reduced soybean yield when untreated, but either herbicide treatment extended that interval to 16 wk.
Aerial Photography and Videography for Detecting and Mapping Dicamba Injury Patterns
Authors: Hickman Michael V. , Everitt James H. , Escobar David E. , Richardson Arthur J.
Published: March 2018

Field trials were conducted to compare on-site visual evaluations with color-infrared photography (CIR), and near-infrared (NIR) videography (video) and hand-held radiometry (HHR) for detecting and mapping dicamba injury in cotton. CIR, video, and HHR detected 48%, 42% and 36%, respectively, of the injured crop area as defined by visual evaluation (injury ratings >0 on a scale of 0 to 9). The remote techniques were unable to differentiate crop injury that did not involve the entire plant canopy. Reflectance measurements in the visible red (R) (630–690 nm) and NIR (760–900 nm) wavelengths were taken and used in herbicide dosage prediction equations. Predicted herbicide dosages were significantly, positively correlated (P≤0.01) with physical measures of herbicide present. These studies suggest that remote detection and mapping of moderate and severe herbicide injury is possible. Further, NIR videography, with near-real-time capability and low cost may be the system of choice for this type of application.
Seeding Date, Seeding Rate, and Row Spacing Affect Wheat (Triticum aestivum) and Cheat (Bromus secalinus)
Authors: Koscelny Jeffrey A. , Peeper Thomas F. , Solie John B. , Solomon Stanley G.
Published: March 2018

Field experiments were conducted in Oklahoma to determine the effects of winter wheat seeding date and cheat infestation level on cultural cheat control obtained by increasing winter wheat seeding rates and decreasing row spacing. Seeding rate and row spacing interactions influenced cheat density, biomass, or seed in harvested wheat (dockage) at two of three locations. Suppressive effects on cheat of increasing wheat seeding rates and reduced row spacings were greater in wheat seeded in September than later. At two other locations, increasing seeding rate from 67 to 101 kg ha–1or reducing row spacings from 22.5 to 15 cm increased winter wheat yield over a range of cheat infestation levels.
Alfalfa (Medicago sativa) Seed Yield Loss Due to Canada Thistle (Cirsium arvense)
Authors: Moyer James R. , Schaalje G. Bruce , Bergen Peter
Published: March 2018

Alfalfa seed yield and Canada thistle densities were measured in 10 fields in southern Alberta to assess the effect of thistles on seed yield. Thistle density and seed yield from each field were fitted to the Weibull, hyperbolic, and linear equations and a random coefficient and linear equation were used to obtain an “average yield loss curve”. Estimated average losses in alfalfa seed yield were >34% and >48% at thistle densities of 10 and 20 shoots m–2, respectively.
Postemergence-Directed Herbicides Control Wild-Proso Millet (Panicum miliaceum) in Sweet Corn (Zea mays)
Authors: Kleppe Craig D. , Harvey Robert G.
Published: March 2018

Thirty-six postemergence-directed (PDIR) herbicide treatments, applied with a precision PDIR sprayer, were evaluated for wild-proso millet (PANMI) control in sweet corn field trials in Wisconsin from 1987 to 1990. The performance of butylate and cyanazine (B + C), applied to suppress PANMI early in the season and to provide a height differential between corn and PANMI, greatly influenced PANMI control with PDIR treatments. PDIR treatments controlled PANMI greater than 90% when PANMI was effectively suppressed by B + C, but poor PANMI suppression reduced PDIR herbicide efficacy. Generally, PDIR treatments of paraquat or sethoxydim most effectively controlled PANMI. Paraquat alone at 545 g ha–1or combined with simazine or sethoxydim at 57 and 114 g ha–1, and sethoxydim at 170 and 227 g ha–1plus an adjuvant controlled PANMI greater than 95%. PDIR applications of ametryn, linuron, sethoxydim at 57 to 227 g ha–1alone, sethoxydim at less than 114 g ha–1plus an adjuvant, and sethoxydim at 114 g ha–1tank mixed with either of four other herbicides controlled less than 86% of PANMI. Tank mixing a photosynthetic inhibitor or sethoxydim with paraquat did not improve PANMI control compared with paraquat alone. PANMI control with sethoxydim plus an adjuvant at 114 g ha–1was similar to 227 g ha–1. There was no difference in PANMI control with sethoxydim applied with crop oil concentrate or BCH-815. With the exception of glyphosate at 318 g ha–1and sethoxydim at 227 g ha–1plus an adjuvant, PDIR treatments did not injure sweet corn in 1987, 1988, or 1990. However, sethoxydim in 1989 at all rates severely injured corn.
2,4-D Amine Antagonism by Salts
Authors: Nalewaja John D. , Woznica Zenon , Matysiak Robert
Published: March 2018

Research was conducted to determine the influence of salts on 2,4-D toxicity to kochia. Calcium, magnesium, sodium, potassium, and iron salts except for sulfate and phosphate salts of calcium and sodium were antagonistic to 2,4-D diethanolamine. None of the ammonium salts antagonized 2,4-D control of kochia. Effects of individual ions generally antagonistic to 2,4-D were additive when in mixture. 2,4-D generally controlled kochia better when mixed with various acids than with their ammonium salts in distilled, sodium bicarbonate, or ferric sulfate water carriers, relating to the lower pH with the acids. However, low pH was not essential in overcoming salt antagonism of 2,4-D for kochia control, nor was 2,4-D always effective with low pH. Sulfate and monobasic phosphate anions were most effective in overcoming sodium bicarbonate and calcium chloride antagonism of 2,4-D. The concentration of diammonium sulfate needed to overcome sodium bicarbonate antagonism of 2,4-D increased with sodium bicarbonate concentration. Diammonium sulfate at 2% (w/v) overcame 1200 mg L–1sodium as sodium bicarbonate. Nonionic surfactants and oil adjuvants also overcame antagonism of 2,4-D caused by water from several sources.
Maximizing Herbicide Efficiency with Mixtures and Expert Systems
Authors: Green Jerry M.
Published: March 2018

A practical and objective system is needed to determine the lowest rates of the most efficacious herbicides to meet each producer's specific weed control problems. Determining which method of weed control to utilize is difficult today with increasing product choices, the growing use and complexity of herbicide mixtures, regulatory pressures to reduce rates, and the closer integration of weed control with other crop decisions. Expert computer systems could improve current practices and use herbicide mixtures as a tool to increase herbicide efficiency. Such systems would account for herbicide dose and mixture responses; select most economical herbicides; optimize adjuvants; recommend control at economic thresholds; and vary rates according to weed spectrum, density, and local environmental conditions. An example using chlorimuron and thifensulfuron illustrates how these systems could use quantitative dose response and mixture information.
Temperature and Relative Humidity Effects on Diphenylether Herbicides
Authors: Wichert Rex A. , Bozsa Robert , Talbert Ronald E. , Oliver Lawrence R.
Published: March 2018

The influence of temperature and relative humidity on the activity of acifluorfen, fomesafen, lactofen, and acifluorfen plus bentazon on prickly sida, pitted and entireleaf morningglory, and common cocklebur was evaluated in a growth chamber. Reduced control of all species was observed at 50% relative humidity as compared to 85% relative humidity when temperatures were higher (32/55 C day/night). Similar response to relative humidity was observed at the lower temperature (25/15 C) when treatments were applied 14 days after emergence (DAE). Changes in temperature at the same relative humidity did not alter herbicidal activity. Delaying application timing from 7 to 14 DAE decreased control by all herbicides except lactofen applied at high relative humidity, which controlled prickly sida at both 7 and 14 DAE.
Temperature and Canopy Development of Velvetleaf (Abutilon theophrasti) and Soybean (Glycine max)
Authors: Patterson David T.
Published: March 2018

Velvetleaf from Mississippi and Wisconsin and soybean (var. Williams) were grown in five temperature regimes (12/4, 19/11, 26/18, 33/25, and 40/32 C day/night) in controlled-environment chambers. Leaf appearance rates increased with temperature in both species, ranging from 0.06 to 0.69 leaves per day in velvetleaf and 0.07 to 0.38 leaves per day in soybean. The threshold temperature for leaf appearance in both species was 5 to 6 C. The largest leaves of both species were produced at 26/18 C. By 55 d after emergence, the greatest total leaf area per plant occurred at 26/18 C or above in both species. Reproductive development occurred earliest at 33/25 C in velvetleaf and at 26/18 C in soybean. This limited vegetative growth in velvetleaf more than in soybean. The weed/crop ratio for total leaf area increased with increasing temperature, indicating that velvetleaf probably would be more competitive with soybean under higher temperatures. The two populations of velvetleaf generally responded similarly to temperatures.
Germination and Growth of Leafflower (Phyllanthus urinaria) as Affected by Cultural Conditions and Herbicides
Authors: Wehtje Glenn R. , Gilliam Charles H. , Reeder Jesse A.
Published: March 2018

Factors affecting the germination and seedling growth of leafflower were evaluated. Germination required exposure to light. Seeds covered with a 1-cm deep layer of pine bark mulch failed to emerge. Maximum seedling development occurred in full exposure to sunlight; shading that reduced light intensity more than 26% was inhibitory. Maximum seed germination (79%) occurred between 25 and 35 C; temperatures outside this range were inhibitory. Germination was strongly influenced by osmotic potential. Osmotic potentials of 0, 304, and 507 kPa resulted in 85, 24 and 14% germination, respectively. PRE applications of either granular formulated oxadiazon at 4.5 kg ha–1, or premixed granular formulated oxyfluorfen + oryzalin at 4.6 + 2.3 kg ha–1, provided a minimum of 85% control. The following POST treatments provided a minimum of 90% control of mature plants: paraquat at 0.21 kg ha–1, glyphosate at 0.56 kg ha–1, oxyfluorfen at 1.12 kg ha–1, and acifluorfen at 2.24 kg ha–1.
Effect of 2,4-D and Dicamba Residues on Following Crops in Conservation Tillage Systems
Authors: Moyer James R. , Bergen Peter , Schaalje G. Bruce
Published: March 2018

Dicamba and 2,4-D, which are used prior to seeding in conservation tillage systems, were applied in late fall and early spring to determine their residual effect on subsequent spring-seeded crops. The herbicides 2,4-D ester and 2,4-D amine with dicamba or glyphosate, applied 0 or 15 d prior to spring seeding, damaged canola, peas, lentils, and alfalfa. The legumes were damaged by spring-applied dicamba. There was also a slight reduction in the total dry matter yield of wheat and barley by 2,4-D applied in spring prior to seeding. All crops tested, except lentils, were tolerant of recommended fall applications of 2,4-D for the control of winter annual flixweed and field pennycress.