bluuebunny/crossref_metadata_2025 huggingface dataset:
Surfactant Structure and Concentration Strongly Affect Rimsulfuron Activity
Authors: Green Jerry M. , Green John H.
Published: March 2018

A nonionic surfactant with the appropriate structure and concentration increased rimsulfuron activity 10-fold. Surfactants sharply increased rimsulfuron activity as concentration increased up to 0.05% (w/w) with slightly more enhancement up to 0.1% (w/w). Surfactants with a wide range of 14 chemical, physical, and surface properties were evaluated on giant foxtail, velvetleaf, and corn. Two properties, HLB (hydrophilic-lipophilic balance) and the physical form of the spray deposit, explained the biological variation. The most active surfactants had an HLB from 12 to 17 and formed a moist gel spray deposit on the leaf on all three species. A separate study with 13 chemically pure linear alcohol ethoxylates supported these conclusions and additionally showed that increasing molecular size increases activity. Because crop injury correlates with weed control, the best surfactant strategy is to maximize weed control at the lowest rimsulfuron rate.
Fertilizer and Downy Brome (Bromus tectorum) Effect on Russian Wheat Aphid (Diuraphis noxis) in Winter Wheat (Triticum aestivum)
Authors: Krall James M. , Miller Stephen D. , Bennett Larry E. , Legg David E.
Published: March 2018

Downy brome serves as an alternative host for Russian wheat aphid (RWA) in winter wheat. In field studies, downy brome infestations of 5 and 39 plants per m2increased RWA-infested winter wheat tillers 1.4 to 2.8 times that seen in non-infested plots, respectively. RWA-infested winter wheat tillers were not reduced consistently by fertilization. Chlorpyrifos reduced the number of RWA-infested winter wheat tillers to 15 to 43% of untreated wheat. Insecticide efficacy was not influenced by downy brome infestation or by fertilizer either band- or broadcast-applied.
Effect of Imazaquin and Chlorimuron Plus Metribuzin on Sicklepod (Cassia obtusifolia) Seed Production and Germination
Authors: Shaw David R. , Hydrick David E.
Published: March 2018

Sicklepod seed production and germination were evaluated in density and weed-free period studies without herbicide treatment and after imazaquin or metribuzin plus chlorimuron were applied PRE in soybean. Neither herbicide nor sicklepod density affected sicklepod seed germination, but delaying emergence of sicklepod from 0 wk to 8 wk after soybean emergence reduced subsequent sicklepod seed germination from 92% to 48%. Increasing sicklepod density from two to eight plants per row m reduced sicklepod seeds per plant, but increased sicklepod seeds per m2, regardless of herbicide. Extending the weed-free period from 0 to 8 wk reduced sicklepod seeds per plant and seeds per m2. Imazaquin and chlorimuron plus metribuzin reduced sicklepod seeds per m2more than 50% at 0 or 2 wk weed-free intervals, compared with nontreated plants at these same intervals.
Interacting Effects on Absorption and Translocation from Tank Mixtures of ALS-Inhibiting and Diphenylether Herbicides
Authors: Shaw David R. , Wesley M. Todd
Published: March 2018

The acetolactate synthase-inhibiting herbicides chlorimuron and imazaquin, and the diphenylether herbicides acifluorfen and lactofen, were applied alone and in all possible combinations to the foliage of common cocklebur, pitted morningglory, and prickly sida to evaluate interacting effects on absorption and translocation. The addition of unlabeled acifluorfen to14C-chlorimuron increased absorption in common cocklebur, pitted morningglory, and prickly sida. Lactofen also increased absorption of14C-imazaquin in all species. Conversely, imazaquin reduced absorption or translocation of14C-acifluorfen in common cocklebur or pitted morningglory, respectively. In all species, absorption was lower when unlabeled chlorimuron or imazaquin was combined with14C-lactofen than when applied alone.
Crop Residue Reduces Jointed Goatgrass (Aegilops cylindrica) Seedling Growth
Authors: Anderson Randy L.
Published: March 2018

Producers need alternative methods to manage jointed goatgrass because there are no herbicides that selectively control jointed goatgrass in winter wheat. The effect of crop residue incorporated in soil on reducing seedling growth of jointed goatgrass was examined in the greenhouse. Residues of corn, proso millet, safflower, grain sorghum, and winter wheat reduced fresh weight of jointed goatgrass by 70 to 85%. Applying N fertilizer at 33 or 66 kg ha−1diminished this effect, indicating that residue stimulated microbial immobilization of N. Ethiozin applied preemergence at 0.2μg g−1soil reduced jointed goatgrass seedling growth by 50%, but combining crop residue with ethiozin did not synergistically improve control of jointed goatgrass. These results suggest that producers may favor winter wheat growth over jointed goatgrass by incorporating crop residue in soil with tillage before planting and by banding N with winter wheat seed at planting.
Effects of Clethodim on Seedhead Density, Forage Yield, and Quality of Tall Fescue (Festuca arundinacea)
Authors: Reynolds John H. , Krueger William A. , Walker Cynthia L.
Published: March 2018

Clethodim was applied to tall fescue to determine the effects of application timing (fall, early spring, mid-spring), rate (0, 5.6, 11.2, or 22.4 g ai ha−1), and use of crop oil (0 or 2.3 L ha−1) on seedhead density and forage yield and quality of tall fescue. Increasing the rate of clethodim or adding crop oil reduced seedhead density and forage yield, and generally improved forage quality. There was no effect of application date in 1988 and 1990, but seedhead density and forage yield decreased from the November to the March application date in 1989.
Use of Critical Nontarget Plants by the Russian Knapweed Nematode, (Subanguina picridis)
Authors: Rosenthal Sara S. , Coombs Eric M. , Haglan Bill , Piper Gary L.
Published: March 2018

During field experiments the Russian knapweed nematode formed no galls on artichoke, one sterile gall on American basketflower, and few nematodes in numerous small galls on southwestern basket flower in comparison with much higher nematode production per gall on Russian knapweed.
Little Lovegrass (Eragrostis minor) Distribution in Idaho and Washington
Authors: Northam Francis E. , Old Richard R. , Callihan Robert H.
Published: March 2018

Little lovegrass, an annual species native to Europe, was not listed in the floras that describe the plants of Idaho and Washington. Twelve collections were made between 1984 and 1992 from four Idaho counties and six Washington counties. Those records extended the range of this species 450 to 1000 km northwest of populations reported in the literature. Approximately 600 km separated the furthest of the new collection sites, indicating widespread naturalization in those states. Eight of the collections were from roadsides, suggesting that human transport technology had a substantial influence on this plant's dispersal.
Weed Control with Bromoxynil Applied Alone and with Graminicides
Authors: Jordan David L. , Smith M. Cade , McClelland Marilyn R. , Frans Robert E.
Published: March 2018

Experiments were conducted in 1991 and 1992 to evaluate annual grass and broadleaf weed control with bromoxynil applied alone and with graminicides. Bromoxynil controlled velvetleaf better than entireleaf morningglory and controlled both species better than sicklepod. Mixing bromoxynil with fluazifop-P, quizalofop-P, and sethoxydim reduced control of barnyardgrass, green foxtail, large crabgrass, and shattercane. Control of broadleaf signalgrass with quizalofop-P was reduced by bromoxynil. Annual grass control with clethodim was not affected by bromoxynil.
Using Satellite Data to Map False Broomweed (Ericameria austrotexana) Infestations on South Texas Rangelands
Authors: Anderson Gerald L. , Everitt James H. , Richardson Arthur J. , Escobar David E.
Published: March 2018

False broomweed is a troublesome weed on south Texas rangelands. The plant suppresses the growth of desirable herbaceous plant species and is unpalatable to livestock and wildlife. The objectives of this study were to evaluate multispectral satellite data for automated detection, classification, and mapping of false broomweed infestations. Determining the optimum phenological conditions for false broomweed detection was a major goal. Results indicate that satellite data can be used to detect major stands of this shrub and map the relative extent of infested areas. The best classification was obtained when the foliage of the shrub was fully developed and during periods of low herbaceous biomass production. Limited ground or aerial surveying will be needed to produce more exact estimates of the extent of false broomweed stands; however, these efforts can be focused on areas identified by satellite classification.
Spring Wheat (Triticum aestivum) Growth and Yield as Influenced by Duration of Wild Oat (Avena fatua) Competition
Authors: Kirkland Kenneth J.
Published: March 2018

The effect of duration of wild oat competition on spring wheat yield and growth was determined in time-of-removal experiments conducted over a three year study period in Saskatchewan, Canada. Failure to remove wild oat reduced wheat yield 28 and 39% at wild oat populations of 64 and 188 plants per m2, respectively. Wheat yield was not reduced by wild oat densities of 64 or 118 plants per m2until the six- and seven-leaf stage of wild oat, respectively. Removing wild oat at 64 plants per m2before the seven-leaf stage and 118 plants per m2before the five-leaf stage did not increase wheat culm or fresh weight production.
Toxicity of Imazethapyr to Purple (Cyperus rotundus) and Yellow Nutsedges (C. esculentus)
Authors: Richburg John S. , Wilcut John W. , Wehtje Glenn R.
Published: March 2018

Greenhouse studies were conducted to determine the response of purple and yellow nutsedges to selective soil placement of 5 cm of soil treated with imazethapyr above and/or below the nutsedge tubers. Early postemergence (EPOST) or postemergence (POST) imazethapyr treatments at 71 g ai/ha as a foliar, soil, or foliar + soil application was also evaluated. Imazethapyr placement above or below the nutsedge tuber generally increased shoot number, shoot dry weight (SW), shoot regrowth dry weight (SRW), and root tuber dry weight (RTW) production in both species, 28 and 42 days after treatment (DAT) compared with the control. However, the 5-cm above + 5-cm below tuber treatment at 14, 28, and 42 DAT reduced purple nutsedge shoot number, SW, SRW, and RTW to 19, 7, 14, and 26% of the control, respectively. Yellow nutsedge shoot number was 103% of the control with the 5-cm above + 5-cm below tuber treatment 42 DAT. The 5-cm above + 5-cm below tuber treatment reduced yellow nutsedge SW, SRW, and RTW to 43, 44, and 23% of the control, respectively, 28 and 42 DAT. EPOST and POST foliar + soil and soil-only applications reduced SW 28 d after treatment (DAT) to 13% or less of the control for both species. SRWs of both species were ≤ 53% of the control 42 DAT for the soil-only application. The foliar-only treatment was the least effective in SW, SRW, and RTW reductions.
Differential Toxicity of Tralkoxydim inHordeumSpecies
Authors: Tal Abraham , Benyamini Yuval , Rubin Baruch
Published: March 2018

In greenhouse studies, tralkoxydim applied POST at 100 to 300 g ai/ha during the three-to four-leaf stage of development were differentially toxic to threeHordeumspecies. Tralkoxydim severely injured wall barley by cessation of growth and death of the whole plant.Hordeum spontaneum, barley, and wheat were less affected by the herbicide in declining order, respectively. However, 4 wk after treatment, full recovery was observed in barley and wheat, but not inH. spontaneum, as reflected in the shoot fresh weight. Tralkoxydim could be considered as a selective herbicide in wheat and barley fields for the control of wall barley.
Field Bindweed (Convolvulus arvensis) Control with Fluroxypyr
Authors: Macdonald Robert T. , Hall J. Christopher , O'Toole James J. , Swanton Clarence J.
Published: March 2018

Experiments were conducted under controlled environment and field conditions to evaluate the influence of growth stage and fluroxypyr dosage on control of field bindweed. In controlled environment studies fluroxypyr effectively controlled 8- to 12-leaf field bindweed. Shoot number, length, and dry weight, and root dry weight decreased as herbicide dose increased. The estimated ED50(effective dose for 50% reduction) values for shoot and root dry weight were 50 and 33 g ai/ha, respectively. The ED50for shoot length was 98 g ai/ha. Fluroxypyr was applied at rates from 0.2 to 0.4 kg/ha under field conditions to field bindweed at selected stages of growth. Regardless of herbicide dosage, fluroxypyr applied at the late flowering stage of growth controlled field bindweed better than when applied at the bud or early flower stage. Corn grain yield increased as a function of fluroxypyr dose in 1988 but not in 1987. Dry weight of roots and shoots of field bindweed harvested one year after treatment decreased with increasing rates of fluroxypyr. These studies demonstrate the potential of fluroxypyr for the control of field bindweed.
Milkweeds
Authors: Mitich Larry W.
Published: March 2018

Of the approximately 120 species of milkweeds (Asclepias spp.), the majority are American natives, principally the U. S. and Canada, where they are widely distributed. Milkweeds are erect, coarse growing perennials with showy white, pink, purple, or orange colored flowers. Milkweed gets its name from the abundance of sticky milky-white juice that exudes from broken stems.
Influence of Several Pesticides and Adjuvants onChondrostereum purpureum—A Bioherbicide Agent for Control of Forest Weeds
Authors: Prasad Raj
Published: March 2018

The basidiomycete fungus,Chondrostereum purpureumFr. Pouzar, has been found to be a good potential bioherbicide candidate for control of hardwood vegetation in forests. However, its interaction with some agrochemicals that are normally employed in forest protection was not known. Employing two concentrations (0.01% v/v and 0.1% v/v) of several agrochemicals, a laboratory study was conducted to assess their impacts on the infective mycelia. Except for Bond, and Suntan gel-2, most adjuvants, sunscreen agents, and pesticides (herbicides, fungicides, and insecticides) were fungitoxic at 0.1%. Fungitoxicity was concentration dependent and the results indicate that the possibility of tank-mixing the basidiomycete with agrochemicals appears limited and the possibility of agrochemical residue effects on survival of the basidiomycete is implied.
Biology of Tropical Soda Apple (Solanum viarum) an Introduced Weed in Florida
Authors: Mullahey J. Jeffrey , Cornell John
Published: March 2018

Understanding the biology of tropical soda apple (TSA) is necessary to develop effective control strategies. Tropical soda apple seedling emergence, growth, and regeneration from roots were evaluated. Plant growth (height, leaf number, flowering) was monitored over 110 d in a greenhouse experiment. Emerged seedlings required 83 d to reach a height of 40 cm and 108 d to flower. Total nonstructural carbohydrate concentrations in TSA root and stem fractions, monitored monthly for 1 yr, were highest in December (35%-root, 18%-stem). Seedling emergence as affected by planting depth (0, 1, 2, 4, 8 cm) and regeneration from root segments (7.5, 15 cm long) placed on the soil surface and 5 and 10 cm deep were studied in separate greenhouse experiments. Seedling emergence was lowest (P < 0.05) for seed placed on the soil surface (6.9%) and at a depth of 8 cm (19.4%) with the highest level of TSA emergence predicted at 63% for seed planted 3.6 cm deep. Regeneration from roots was higher (P < 0.05) for the 15-cm root segments than for the 7.5-cm segments while depth of root segment placement did not affect regeneration. Weed control strategies should involve cultural and chemical practices that affect both roots and seeds.
Leafy Spurge (Euphorbia esula) Control with Imidazolinone and Sulfonylurea Herbicides
Authors: Stougaard Robert N. , Masters Robert A. , Nissen Scott J.
Published: March 2018

Experiments were conducted to determine the efficacy of imidazolinone and sulfonylurea herbicides applied alone or in combination to control leafy spurge. Imazapyr (840 g ai/ha), imazethapyr (140 g/ha), sulfometuron (100 g/ha), and chlorsulfuron (20 g/ha) were applied in the fall on rangeland sites near Ainsworth and Columbus, NE. Imidazolinone and sulfonylurea herbicide combinations did not improve leafy spurge control nor affect forage grass yields when compared with herbicides applied alone. Imazapyr and sulfometuron were the most efficacious, providing greater than 80% leafy spurge control 9 mo after treatment (MAT). Imazethapyr provided 80% control of leafy spurge 9 MAT when applied to a coarse textured, low organic matter soil. In contrast, leafy spurge control was only 15% when imazethapyr was applied to a fine textured soil. Chlorsulfuron did not control leafy spurge, regardless of site characteristics. Imazapyr reduced perennial grass yields by more than 60%.
2,4-D Safening of Nicosulfuron and Terbufos Interaction in Corn (Zea mays)
Authors: Simpson David M. , Diehl Kevin E. , Stoller Edward W.
Published: March 2018

Normal field applications of both terbufos and nicosulfuron can cause decreased corn tolerance to nicosulfuron because terbufos inhibits nicosulfuron metabolism. In greenhouse studies, applications of 2,4-D at 0.07, 0.14, and 0.28 kg/ha with nicosulfuron reduced terbufos induced foliar injury by more than 50%. Plants treated with nicosulfuron, terbufos, and 2,4-D had significantly higher shoot dry weights than those treated with nicosulfuron and terbufos. When 2,4-D was applied sooner than 24 h before nicosulfuron application or later than 24 h after nicosulfuron application, it did not prevent the interaction. Uptake of 14C-nicosulfuron was increased by the presence of terbufos but was unaffected by 2,4-D. Translocation of 14C-nicosulfuron was low with the highest amounts occurring in the nicosulfuron plus terbufos treatment. Terbufos reduced metabolism of nicosulfuron at 4 and 24 h after treatment compared to plants without terbufos. Metabolism of nicosulfuron in plants treated with terbufos was increased by 2,4-D to a rate equivalent to that in plants not treated with terbufos.
Response of Canada Thistle (Cirsium arvense) and Leafy Spurge (Euphorbia esula) Clones to Chlorsulfuron, Clopyralid, and Glyphosate
Authors: Frank J. Ray , Tworkoski Thomas J.
Published: March 2018

Response of clones of Canada thistle from North America and leafy spurge from North America and Eurasia to treatment with chlorsulfuron, clopyralid, and glyphosate was determined. Roots of Canada thistle plants from different locations responded differentially to injury from chlorsulfuron and clopyralid but not to glyphosate. Clones of Canada thistle varied significantly in response to all herbicide treatments. Roots of leafy spurge plants from different locations were differentially susceptible to injury from glyphosate. Clones of leafy spurge varied significantly for all responses to each herbicide. The differential effects of chlorsulfuron, glyphosate, and clopyralid on clones of Canada thistle and leafy spurge suggest that genetically-based differences may account for the failure of the herbicides to kill all plants within collection locations or between collection locations. Cross tolerance to the herbicides was not found in leafy spurge or Canada thistle.
Residues of the Herbicides MCPA and Bromoxynil in Postemergence-Treated Triticale (×Triticosecale)
Authors: Cessna Allan J.
Published: March 2018

In a two-year study involving two sites in western Canada, the dissipation of bromoxynil octanoate alone at 0.35 or 0.42 kg phenol equivalent (pe)/ha and the tank mixture of MCPAiso-octyl ester at 0.28 kg ae/ha plus bromoxynil octanoate at 0.28 kg pe/ha was monitored in postemergence-treated triticale. Initial foliar residues on the day after application (three- to four-leaf stage of the crop) were of the order of 14 and 5 mg/kg for MCPA and bromoxynil, respectively. Residues of both herbicides decreased to less than the limit of quantification (0.025 mg/kg) of the analytical method 21 d after application. At crop maturity, herbicide residues were non-detectable in the straw and seed. There was little or no effect on the dissipation of bromoxynil residues due to tank mixing with MCPA.
Sethoxydim Response to Spray Carrier Chemical Properties and Environment
Authors: Nalewaja John D. , Matysiak Robert , Szelezniak Edward
Published: March 2018

Experiments were conducted to determine the influence of spray carrier salts, UV light, and temperature on sethoxydim phytotoxicity to oat or yellow foxtail. Spray solution pH and ions present were both important to sethoxydim phytotoxicity to oat. Sodium and calcium salts were antagonistic to sethoxydim phytotoxicity only when the spray carrier pH exceeded 7. Ammonium salts and ammonium hydroxide were synergistic with sethoxydim, and the synergism was independent of spray solution pH. Ammonium sulfate, but not ammonium hydroxide, overcame sodium bicarbonate antagonism of sethoxydim. The antagonism of sethoxydim phytotoxicity by sodium bicarbonate was greatest in the presence of UV light and most pronounced when treated plants were exposed to mid-day sunlight. Sodium bicarbonate or low temperature may reduce the speed of sethoxydim absorption allowing for greater UV degradation of unabsorbed sethoxydim on the leaf surface.
Evaluation of Imazethapyr for Weed Control in Leafy Vegetable Crops
Authors: Dusky Joan A. , Stall William M.
Published: March 2018

Imazethapyr was evaluated PRE and POST in five lettuce types and chicory under Florida field conditions. The relative sensitivity of leafy crop vigor (most sensitive to most tolerant) to imazethapyr PRE, based on 20% inhibition determined using regression analysis, was as follows: Boston > bibb > crisphead > romaine > leaf > escarole > endive. Leafy crop injury increased as the rate of imazethapyr applied POST increased, with all leafy crops responding in a similar manner. Surfactant addition increased imazethapyr phytotoxicity. Imazethapyr PRE treatments at 0.067 kg ai/ha provided greater than 80% control of livid amaranth, common purslane, flatsedge, and common lambsquarters. Imazethapyr POST at 0.067 kg/ha, with surfactant provided control greater than 85% of all weed species. Greater than 85% spiny amaranth control was provided by imazethapyr POST at 0.017 kg/ha. Use of surfactant with imazethapyr did not improve spiny amaranth control over imazethapyr with no surfactant. POST treatments did not decrease leafy crop yield compared with the hand-weeded check. Imazethapyr applied PRE reduced crop yield compared to the POST treatments and the hand-weeded control.
Effects of Weeds and Herbicides on Sweetpotato (Ipomoea batatas) Transplant Production Using Polyethylene Bed Covers
Authors: Monks David W. , Schultheis Jonathan R. , Mills Robert J.
Published: March 2018

Studies determined the effect of common lambsquarters, goosegrass, and a mixture of these on ‘Beauregard’ and ‘Jewel’ sweetpotato transplant production with or without polyethylene bed covers. Effects of herbicides on Beauregard in propagation beds were also studied. Black and infrared transmissible (IRT) plastic covers gave near 100% control of goosegrass and common lambsquarters, resulting in the greatest number and weight of Jewel transplants per plot. Common lambsquarters reduced transplant number and weight per plot with Jewel under clear plastic covers when compared with black and IRT plastic covers. Beauregard transplant number was not affected by row cover treatment. However, with data combined over all covers, Beauregard transplant weight per plot was lowest for treatments with weeds compared to weed-free plots. With the exception of DCPA, no significant (10% or greater) injury to Beauregard was observed with diphenamid, napropamide, chloramben, or chloramben plus fluazifop.
Effects of Repeated Applications of Trifluralin and Pendimethalin on Cotton (Gossypium hirsutum)
Authors: Keeling J. Wayne , Dotray Peter A. , Abernathy John R.
Published: March 2018

The dinitroaniline herbicides, trifluralin and pendimethalin, are applied to approximately 90% of land seeded to cotton on the Texas Southern High Plains. Trifluralin and pendimethalin at 0.6 and 1.1 kg ai/ha were applied annually to plots from 1983 through 1994. Cotton stand counts, lint yield, and fiber quality varied from year-to-year due to environmental conditions. Differences in lint yield or fiber quality over the 11-yr period were not related to herbicide applications.
Interactions Between SAN 582H and Selected Safeners on Grain Sorghum (Sorghum bicolor) and Corn (Zea mays)
Authors: Kotoula-Syka Eleni , Hatzios Kriton K. , Meredith Sue A.
Published: March 2018

The efficacy of the safeners naphthalic anhydride (NA), CGA-92194, and CGA-133205 as protectants of grain sorghum and of NA, R-29148, CGA-154281, and dichlormid as protectants of corn against injury from the chloroacetamide herbicide, SAN 582H, was evaluated under greenhouse conditions. SAN 582H applied alone reduced the shoot growth of ‘Funk G522DR’ and ‘Funk G623’ sorghum, but had no effect on the growth of the ‘GP-10’ genotype of sorghum. Corn (‘Northrup-King 9283’ hybrid) was considerably more tolerant than grain sorghum to SAN 582H. The rate of SAN 582H causing 50% reduction of corn shoot height (GR50) was 5.1 kg/ha as compared to 1.1 kg/ha for grain sorghum. NA applied as seed dressing at 5 or 10 g/kg seed, provided moderate protection to ‘G522DR’ and ‘G623’ sorghum and no protection to corn against SAN 582H injury. Dressing of sorghum seeds with CGA-133205 provided moderate protection to G522DR sorghum, whereas seed-applied CGA-92194 provided moderate protection to G623 sorghum against SAN 582H. The dichloroacetamide safeners R-29148, dichlormid, and CGA-154281 were all effective as protectants of corn against SAN 582H injury. These results demonstrate that, as with other chloroacetamide herbicides, the tolerance of corn and grain sorghum to SAN 582H can be enhanced with the use of safeners of the dichloroacetamide type and oxime ether type, respectively.
Reduced Rates of Herbicides Following Hilling Controlled Weeds in Conventional and Reduced Tillage Potato (Solanum tuberosum) Production
Authors: Bellinder Robin R. , Wallace Russell W. , Wilkins Erik D.
Published: March 2018

Time of hilling (4, 5, or 6 weeks after planting; WAP) and 0.5x, 1x, and split (0.5x + 0.5x) rates of metolachlor + metribuzin were evaluated in conventional tillage (CT) and rye-stubble, reduced tillage (RT) potato plots. Weed populations 4 to 10 WAP were generally higher in CT than in RT. Weed control was excellent in both tillage systems when 1x rates of metolachlor + metribuzin were applied delayed preemergence, or in a split application where 0.5x was applied delayed PRE and hilled 6 WAP, and followed with a second application of 0.5x metolachlor + metribuzin 7 days after hilling (DAH). Weed control with 0.5x rates of metolachlor + metribuzin applied 7 DAH, when hilled 4 and 5 WAP, was equivalent to the lx and split-rate treatments. Weed control was reduced only when hilling was delayed to 6 WAP and 0.5x of metolachlor + metribuzin applied 7 DAH. Total yields were not influenced by tillage, hilling, or herbicide treatment, however, larger numbers of green and small-sized tubers reduced marketable yields in RT.
Effect of Reduced Dithiopyr and Prodiamine Rates on Large Crabgrass (Digitaria sanguinalis) Control in Common Bermudagrass (Cynodon dactylon) and Tall Fescue (Festuca arundinacea) Turf
Authors: Johnson B. Jack
Published: March 2018

Dithiopyr and prodiamine are new preemergence herbicides for crabgrass control in tall fescue and bermudagrass turf. A field experiment was conducted over a 2-yr period to determine the lowest rates of dithiopyr and prodiamine needed to control large crabgrass effectively in tall fescue and common bermudagrass. Prodiamine applied at 0.17 kg ai/ha in each of two applications controlled 92 to 93% of large crabgrass by late August in common bermudagrass and 78 to 85% in tall fescue. Dithiopyr applied at 0.11 kg ai/ha in each of two applications controlled 85 to 89% of large crabgrass in common bermudagrass, but the control was not consistent across years at any rate in tall fescue. Dithiopyr applied at 0.56 kg/ha on tall fescue controlled 91% of large crabgrass in 1993, but only 38% in 1994. The higher control with dithiopyr in common bermudagrass was due to greater competition with germinating large crabgrass seeds and emerging seedlings during the summer, compared with little or no competition from tall fescue. The quality of tall fescue and common bermudagrass treated with dithiopyr and prodiamine was generally higher in plots where large crabgrass was effectively controlled than in plots with poor control. In general, dithiopyr did not control large crabgrass as effectively in tall fescue as in common bermudagrass, while the control with prodiamine was similar for the two turfgrass species.
Enhancing Riparian Habitat for Fish, Wildlife, and Timber in Managed Forests
Authors: Newton Michael , Willis Ruth , Walsh Jennifer , Cole Elizabeth , Chan Samuel
Published: March 2018

The productivity of riparian sites in managed forests can be focused to provide productive fish and wildlife habitat while yielding most of its productive capacity for other than amenity values. Establishment of habitat protection goals and measures of achievement permit flexible approaches for meeting them. Once the protection standards are set, intensive management of the woody cover is logically dependent on minimum disturbance methods, in general, for both vegetation management and harvest. Several currently registered chemical products and non-chemical methods are helpful and safe in achieving both yield and protection goals.
Wild Carrot (Daucus carota L.)
Authors: Mitich Larry W.
Published: March 2018

“Cool white, and intricate, Queen Anne's lace hedges our summer highways with spendthrift loveliness. But who of us can imagine the full beauty and wonder of this plant as we speed by?”—Green Immigrants by Claire Shaver Haughton.
Interaction of Surfactant Dose and Spray Volume on Rimsulfuron Activity
Authors: Green Jerry M.
Published: March 2018

Surfactant concentrations from 0.0008 to 12.5% (w/w) in spray volumes from 19 to 475 L/ha were tested with and without rimsulfuron on giant foxtail. Both factors varied at 5-fold increments so treatments with equal surfactant concentrations and rates could be compared. As surfactant concentration increased from 0.0008 to 0.1%, rimsulfuron activity increased from less than 20% to more than 90% growth inhibition. This increase was dependent on surfactant concentration. As surfactant concentration increased from 0.5 to 12.5%, rimsulfuron activity decreased to less than 20% at all spray volumes. This decreased activity and the associated surfactant phytotoxicity was dependent on surfactant rate, not concentration. Thus rimsulfuron can be much less active when applied with too little or too much surfactant.
The Effect of Chlorimuron/Linuron Combinations on Soybean (Glycine max) Growth and Yield
Authors: Prostko Eric P. , Majek Brad A. , Ingerson-Mahar Joseph
Published: March 2018

Field studies were conducted to evaluate the effects of chlorimuron + linuron combinations on soybean growth and yield. PRE applications of chlorimuron + linuron were applied at rates of 0.03 + 0.31, 0.04 + 0.50, 0.05 + 0.62, and 0.10 + 1.24 kg ai/ha. Soybean emergence was not reduced by any herbicide rate. Plant heights were significantly reduced by all rates 5 WAT but the plants recovered from this injury by 19 WAT. Pod production and yield were not reduced by chlorimuron + linuron combinations.
Off-Site Runoff Losses of Metolachlor and Metribuzin Applied to Differing Soybean (Glycine max) Production Systems
Authors: Webster Eric P. , Shaw David R.
Published: March 2018

Three soybean production systems coupled with conventional tillage (CT) or no-tillage (NT) were evaluated for metolachlor and metribuzin loss in water from runoff. Metolachlor and metribuzin concentrations were similar in runoff from CT or NT soybean following winter wheat, with stubble burned, and CT or NT monocrop soybean. However, metolachlor and metribuzin concentrations were higher in runoff water from the CT doublecrop soybean planted into winter wheat stubble than NT. In all 3 yr of the study, the majority of total losses occurred in the first three runoff events. Total loss of metolachlor in runoff from the doublecrop system with winter wheat stubble present was 0.6% in 1991 to 1.1% in 1990 from CT, and 0.2% in 1990 to 0.6% in 1991 from the NT. Similar results were observed from the CT and NT doublecrop with burned winter wheat stubble and the monocrop systems. Metribuzin loss patterns were similar to metolachlor, but the fraction lost was slightly higher. Multi-variate regression was used to describe and predict herbicide losses, and R2values ranged from 0.66 to 0.98 for both metolachlor and metribuzin.
Diluent Volume Influences Susceptibility of Field Bindweed (Convolvulus arvensis) Biotypes to Glyphosate
Authors: Yerkes Carla N. Duncan , Weller Stephen C.
Published: March 2018

Two biotypes of field bindweed differing in their susceptibility to glyphosate were used to determine if diluent or carrier volume and additional surfactant could overcome differences in intraspecific response to glyphosate. In greenhouse studies, glyphosate (formulated product) was applied at 1.68 kg/ha in three diluent volumes (142, 189, and 237 L/ha), with and without 1 % (v/v) additional amphoteric surfactant. Nonparametric and ordinal categorical analyses indicated that field bindweed biotype, diluent volume, and surfactant significantly increased glyphosate phytotoxicity 7 DAT. Only biotype and volume were significant 21 DAT. The tolerant biotype was less injured at the 189 and 237 L/ha volumes than the susceptible biotype. Field bindweed injury was similar at a diluent volume of 142 L/ha for both biotypes. These greenhouse studies suggest that control of field bindweed may be improved with glyphosate by using low spray volume in concert with additional surfactant.
Root Biology of Grasses and Ecology of Rhizobacteria for Biological Control
Authors: Skipper Horace D. , Ogg Alex G. , Kennedy Ann C.
Published: March 2018

Rhizobacteria are being evaluated for promotion of plant growth and for biological control of weeds, insects, diseases, and nematodes. Although considerable efforts have been allocated to this approach to biological control, commercial success remains elusive yet intriguing. In this review, the root biology of downy brome and winter wheat is described as an initial model of the information needed for other plant hosts. A limited review of rhizobacteria in disease management is presented to demonstrate the potential and some limitations with rhizobacteria as biocontrol agents. Several techniques are described to improve the survival of a rhizobacterium to suppress downy brome. To achieve success with rhizobacteria in pest management, more information is needed on the root biology of the host plants and the ecology of the rhizobacteria.
Chemical Interactions with Bioherbicides to Improve Efficacy
Authors: Hoagland Robert E.
Published: March 2018

Bioherbicides can be defined as plant pathogens, phytotoxins derived from pathogens or other microorganisms, augmentatively applied to control weeds. Although many pathogens with bioherbicidal potential have been discovered, most lack sufficient aggressiveness to overcome weed defenses to achieve adequate control. Plants use various physical and biochemical mechanisms to defend against pathogen infectivity, including callose deposition, hydroxyproline-rich glycoprotein accumulation, pathogenesis-related proteins (PR-proteins), phytoalexin production, lignin and phenolic formation, and free radical generation. Some herbicides, plant growth regulators, specific enzyme inhibitors, and other chemicals can alter these defenses. Various pathogens also produce chemical suppressors of plant defenses. Secondary plant metabolism is a major biochemical pathway related to several defense processes. Increased activity of a key enzyme of this pathway, phenylalanine ammonia-lyase (PAL), is often a response to pathogen attack, as demonstrated in two weeds and their associated bioherbicidal pathogens:Alternaria cassiaeon sicklepod andA. crassaon jimsonweed. Weakening of physical and biochemical defenses, and lowering of resistance to pathogen attack, may result from reduced production of phenolics, lignin, and phytoalexins caused by herbicides and other chemicals that affect cuticular component biosynthesis and/or key aspects of secondary plant metabolism. Potent PAL inhibitors [aminooxyacetic acid, α-aminooxy-β-phenylpropionic acid, and (l-amino-2-phenylethyl)phosphonic acid] have some regulatory action on secondary plant metabolism and pathogenicity. Various herbicides and other chemicals dramatically affect extractable PAL activity levels and/or substantially alter PAL product production. Some non-pathogenic organisms can alter herbicide efficacy, and some herbicides influence disease development in plants. Research has shown some synergistic interactions of microbes and chemicals with relevance to weed control. Further research on pathogen interactions with agrochemicals (or other chemicals/regulators) could result in increased efficacy of pathogen-herbicide combinations, reduction of herbicide and pathogen levels required for weed control, and expanded pathogen host range.
Suppression of a Perennial Subspecies of Annual Bluegrass (Poa annuaspp.reptans) in a Creeping Bentgrass (Agrostis stolonifera) Green with Plant Growth Regulators
Authors: Johnson B. Jack , Murphy Tim R.
Published: March 2018

Paclobutrazol and flurprimidol were evaluated for suppression of a perennial subspecies of annual bluegrass in a creeping bentgrass green. Three applications of paclobutrazol in the spring (Mar. 17, Apr. 17, and May 17) followed by three applications in the fall (Oct. 2, Nov. 2, and Nov. 30) suppressed the perennial subspecies ≥ 72% at 3 wk after the final treatment. However, suppression was reduced to ≤ 57% by 4 mo after the final fall application. Flurprimidol applied in three spring and three fall applications did not suppress the perennial subspecies as effectively as paclobutrazol. Suppression was ≤ 47% at 3 wk after the final flurprimidol treatment and was only ≤ 20% by mid-March. Neither chemical injured creeping bentgrass greater than 20% in the spring. However, leaf discoloration injury from the initial October application ranged from 26 to 30% for paclobutrazol in 1993 and 21 to 28% for flurprimidol in 1994. When injury occurred in October it was temporary and the creeping bentgrass recovered within 3 to 4 wk. Paclobutrazol and flurprimidol applied in November did not injure creeping bentgrass.
Cover Crops for Herbicide Replacement in No-tillage Corn (Zea mays)
Authors: Yenish Joseph P. , Worsham A. Douglas , York Alan C.
Published: March 2018

Weed control by rye, crimson clover, subterranean clover, and hairy vetch cover crops was evaluated in no-tillage corn during 1992 and 1993 at two North Carolina locations. Weed biomass reduction was similar with rye, crimson clover, and subterranean clover treatments, ranging between 19 and 95% less biomass than a conventional tillage treatment without cover. Weed biomass reduction using hairy vetch or no cover in a notillage system was similar averaging between 0 and 49%, but less than other covers approximately 45 and 90 d after planting. Weed biomass was eliminated or nearly eliminated in all cover systems with PRE plus POST herbicide treatments. Weed species present varied greatly between years and locations, but were predominantly common lambsquarters, smooth pigweed, redroot pigweed, and broadleaf signalgrass. Corn grain yield was greatest using PRE herbicides or PRE plus POST herbicides, averaging between 16 to 100% greater than the nontreated control across all cover treatments depending on the year and location.
Wild Mustard (Brassica kaber) Resistance to Ethametsulfuron But Not to Other Herbicides
Authors: Jeffers G. Mark , O'Donovan John T. , Hall Linda M.
Published: March 2018

In 1993, a wild mustard population growing in a canola crop near Wetaskiwin, AB was poorly controlled by ethametsulfuron after only one previous use of the herbicide. Controlled environment experiments were conducted to compare the response of this suspected resistant population (R) with that of a known susceptible population (S) collected near Vegreville, AB to increasing rates of ethametsulfuron, metsulfuron, chlorsulfuron, thifensulfuron, HOE 075032, imazamethabenz, imazethapyr, metribuzin, and 2,4-D. The R wild mustard population was highly resistant to ethametsulfuron, slightly resistant to low rates of metsulfuron but not resistant to any of the other herbicides tested. This suggests that the mechanism of resistance may differ from that reported for other sulfonylurea and imidazolinone herbicides. Since resistance was documented after only 2 yr of ethametsulfuron use, the initial frequency of resistance to this herbicide in wild mustard populations may be very high. Dry weight of untreated plants did not differ significantly between the S and R populations suggesting little or no differences in competitiveness between them.
Using a Geographic Information System (GIS) for Herbicide Management
Authors: Mitchell Keith M. , Pike David R. , Mitasova Helena
Published: March 2018

An algorithm was developed for use in a geographic information system (GIS) to model the surface movement of herbicide in response to a rainfall event as modulated by slope, soil, management practices, and time of herbicide application. This algorithm was implemented in the GIS software Geographic Resource Analysis Support System (GRASS) and uses as submodels the Natural Resources Conservation Service (NRCS) curve number procedure, the Universal Soil Loss Equation (USLE), and the pesticide submodel from the model Chemicals, Runoff, and Erosion from Agricultural Management Systems (CREAMS). The algorithm estimates the loss of pesticide from field areas, runoff flow patterns, and the accumulation of pesticide downslope in response to a rainfall event. The simulated movement of atrazine, cyanazine, and alachlor was studied under hypothetical management scenarios in the Lake Pittsfield watershed in Pike Co., IL. Tillage for the simulation was by moldboard plow. An alternate no-till scenario was simulated to test tillage effect on atrazine movement. Herbicides were applied either PPI, PRE, POST, or early preplant for no-till (treated as same application time as PPI but without incorporation). The experiment was designed to incorporate timing of application as a management factor from the standpoint of a single rain event on May 16. The results used for comparison were data from 1 d after POST application, 15 d after PRE application and 30 d after PPI application. The algorithm showed that areas of greater herbicide risk can be located within a watershed and that the effect of alternative management practices can be evaluated using a GIS.
Comparison of Fall Versus Spring Applications of Sulfometuron for Common Bermudagrass (Cynodon dactylon) Release
Authors: Taylor James M. , Coats G. Euel
Published: March 2018

A study was conducted to evaluate effects of application timing and sulfometuron rate on weed control and bermudagrass tolerance. Sulfometuron was applied at rates from 13 to 105 g ai/ha and compared to 1120 g ae/ha 2,4-D amine. Control of Italian ryegrass and common vetch was not affected by October, November, December, or March application dates and 39 to 105 g/ha sulfometuron provided equivalent control of both species 6 mo after the initial treatment. Percent green cover of bermudagrass at 6 mo after the initial treatment was 22% or less following March applications compared to 36% or greater when applied in October, November, or December. More bermudagrass injury occurred following March treatments of 52 g/ha or greater sulfometuron where green cover was 14% and less compared to 22 and 30% green cover following 13 g/ha sulfometuron or 1120 g/ha 2,4-D amine, respectively.
Invasion Resistance of Tall Fescue (Festuca arundinaceae) and Perennial Ryegrass (Lolium perenne) to Kikuyugrass (Pennisetum clandestinum)
Authors: Elmore Clyde L. , Gibeault Victor A. , Cudney David W.
Published: March 2018

Overseeding established kikuyugrass swards with tall fescue or perennial ryegrass reduced kikuyugrass cover. Renovation prior to seeding did not aid in the establishment of these two species. Increasing the seeding rate from 79 to 157 kg/ha improved the establishment of perennial ryegrass but not tall fescue. When kikuyugrass plugs were introduced into established turf, tall fescue reduced the invasion of kikuyugrass stolons more than perennial ryegrass. Tall fescue reduced percent kikuyugrass cover, number and spread of stolons, and biomass (compared to perennial ryegrass). The newer turf-type tall fescue cultivars ‘Bonsai,’ ‘Falcon,’ and ‘Olympic’ were more effective than the older tall fescue cultivar ‘Fawn’ in reducing kikuyugrass invasion by reducing stolon number, stolon length, and biomass.
Sweet Corn (Zea mays) Hybrids Respond Differently to Simulated Imazethapyr Carryover
Authors: Rabaey Thomas L. , Harvey R. Gordon
Published: March 2018

Eleven sweet corn hybrids representing a wide range of injury with imazethapyr in a greenhouse study were evaluated in simulated imazethapyr carryover field studies conducted at Arlington, WI. Imazethapyr at 0, 11, 22, and 44 g ai/ha was applied and incorporated 15 d prior to planting sweet corn. The greatest injury occurred 28 d after planting, with reductions in height ranging from 0 to 25%. Reductions in corn ear yields were similar all years for 10 of the 11 hybrids. Reductions in corn ear yield for ‘Crisp N’ Sweet 710,’ ‘Cornucopia,’ ‘Super Sweet Jubilee,’ ‘Excellency,’ and ‘DMC 20–35′ were less than for ‘Natural Sweet 9000,’ ‘Jubilee,’ ‘Zenith,’ ‘Green Giant 40,’ and ‘Green Giant 97.’ In 1992, plots were prepared for an actual imazethapyr carryover study by applying imazethapyr PPI at 70 and 140 g/ha and planting soybean. In 1993, four sweet corn hybrids were planted. Corn ear yield of Green Giant 97 was reduced following previous-year applications of 140 g/ha imazethapyr. Corn ear yields of Excellency, Super Sweet Jubilee, and Jubilee were not reduced at either actual carryover rate. These studies indicate variability among sweet corn hybrids in susceptibility to imazethapyr. Greenhouse results were indicative of field responses and may be useful as a rapid test to determine hybrid susceptibility.