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Browsing by Author "Hagood, Edward S."

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Biology and Control of Eastern Black Nightshade, Palmer Amaranth, and Common Pokeweed, in No-Till Systems on the Eastern Shore Regions of Virginia and Maryland
Vollmer, Kurt Matthew (Virginia Tech, 2014-12-05)
Eastern black nightshade, Palmer amaranth, and common pokeweed are three hard to control weed species on the Eastern Shore regions of Virginia and Maryland. Herbicide resistance and lack of herbicide efficacy further complicate the job of controlling these weeds. Studies were conducted on each of these weeds in order to determine herbicide efficacy and potential herbicide resistance. In addition, the translocation and metabolism of 14C-glyphosate was studied in common pokeweed. This research identified a population of eastern black nightshade that was differentially sensitive to families of ALS-inhibiting herbicides, with tolerance to members of the sulfonylurea family, but controlled with herbicides of the imidazolinone family. A population of Palmer amaranth was found to be glyphosate-resistant, but herbicide programs were identified that could control this biotype in soybean and corn systems. Experiments on the fate of glyphosate in common pokeweed indicated that glyphosate does not readily translocate from treated foliage to other plant parts, which may contribute to shoot regeneration from taproots following glyphosate treatment. Taken together, this research highlights the important weed control issues, including resistant and perennial weeds in agronomic crops that have arisen in Eastern Shore agriculture. This work will help growers to better assess their particular control issues, and take appropriate steps to mitigate any problems.
Characterizing Oxadiazon Resistance and Improving Postemergence Control Programs for Goosegrass (Eleusine indica) in Bermudagrass (Cynodon spp.)
Cox, Michael Christopher (Virginia Tech, 2014-04-16)
Goosegrass is a problematic weed of golf courses, sports fields, and residential lawns that decreases playability and aesthetic quality of turf. With the recent banning of MSMA in sports fields and intensive restrictions in golf and sod production, turfgrass managers are seeking alternatives for postemergence goosegrass control and how to utilize currently labeled goosegrass control products more effectively. Studies were conducted to investigate a suspected-resistant (SR) goosegrass accession in Richmond, VA and characterize the resistance mechanism if present. The SR accession showed a hypersensitive response to oxadiazon treatment and reached maximum electrolyte leakage quicker than the susceptible (S) accession, but had significantly lower electrolyte leakage indicating less tissue damage and suggesting there is a physiological resistance mechanism within the SR accession. In absorption and translocation studies, percent oxadiazon absorption and translocation was not significantly affected by goosegrass biotype. Roots of both the S and resistant (R) biotypes contained over 95% of total detected oxadiazon, while the plant tissue above the treated foliage only contained small quantities. These results suggest that absorption or translocation is not the mechanism conferring oxadiazon resistance in the goosegrass biotype from Richmond, VA. Greenhouse and field trials were conducted to determine the lowest rate at which topramezone, with or without the addition of triclopyr, controls goosegrass while maintaining commercially-acceptable bermudagrass quality. In field trials, topramezone rate did not significantly affect goosegrass cover at 56 and 70 days after initial treatment (DAIT). All treatments reduced goosegrass cover below 3 and 7% with and without the addition of triclopyr, respectively at 70 DAIT. A significant herbicide effect on bermudagrass cultivar showed higher injury from topramezone within three weeks of application, but injury persisted longer from treatments containing triclopyr. Bermudagrass cultivars completely recovered by 4 weeks after treatment (WAT) from all treatments. Greenhouse trials were conducted to determine if goosegrass growth stage affects efficacy of nine postemergent herbicides or programs documented to have goosegrass activity. As goosegrass growth stage increased from four- to five-leaf to greater than eight-tiller stage, goosegrass control and biomass reduction decreased among all of the herbicides except topramezone and MSMA plus metribuzin at 4 and 8 WAT. These data suggest that one application of sulfentrazone is only effective for seedling stage (pre-tiller) goosegrass control; foramsulfuron, topramezone, and metribuzin suppress all growth stages of goosegrass; and diclofop, sulfentrazone plus metribuzin, fenoxaprop, and metamifop control up to three-tiller stage goosegrass.
Combination effect of ACP 2100, imazaquin and triclopyr on common dandelion and three Kentucky bluegrass turf types
Vollmer, Jennifer Sue Landwehr (Virginia Polytechnic Institute and State University, 1989)
The compatibility of ACP 2100, a member of the imidazolinone family (chemistry not released), imazaquin (2- [4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H̱-imidazol2- yl]-3-quinolinecarboxylic acid) and triclopyr {[(3,5,6-trichloro-2-pyridinyl)oxy]acetic acid} was investigated for use in a turf management program, including growth regulation and broadleaf weed control. Field and greenhouse results indicated an antagonistic interaction between triclopyr and imazaquin for control of common dandelion (Taraxacum officinale Weber in Wigger). Addition of imazaquin at 276 g ha⁻¹ to triclopyr at 138 g ha⁻¹ resulted in less dandelion control than 138 plus 138 g ha⁻¹, respectively. Greenhouse and laboratory studies indicated a synergistic interaction between ACP 2100 and triclopyr, not apparent in the field. Addition of ACP 2100 to triclopyr at 34 and 69 g ha⁻¹ resulted in less than expected dandelion biomass, indicating increased dandelion control. ACP 2100 initially decreased triclopyr uptake, but resulted in greater uptake 48 hours after treatment. ACP 2100 also increased triclopyr translocation to the crown, root and middle rosette leaves. In the field and greenhouse, triclopyr did not influence growth regulation and decreased turf injury caused by ACP 2100. Studies showed that as the rate of ACP 2100 increased with the rate of triclopyr an antagonism occurred, resulting in decreased turf injury. The low rate of both ACP 2100 and imazaquin in combination resulted in equal turf growth regulation activity to the high rate of either chemical alone or in combination. One greenhouse study indicated that the interaction was synergistic for height suppression with ACP 2100 and imazaquin at rates of 12 plus 17 or 24 g ha⁻¹, respectively. However, field studies showed that ACP 2100/imazaquin combinations resulted in unacceptable injury to ‘l90’ and ‘Glade-Plush-Ram’ Kentucky bluegrass (Poa pratensis L.). The best turf quality, growth regulation and dandelion control was achieved with a combination of ACP 2100 at 96 and 144 g ha⁻¹ plus triclopyr at 276 g ha⁻¹. These results indicate that turf management costs may be reduced without sacrificing dandelion control by incorporating a chemical mowing program into a spring herbicide treatment.
Control of Common Pasture and Hayfield Weeds in Virginia and West Virginia
King, Steve Russell; Chandran, Rakesh S.; Hagood, Edward S.; Bradley, Kevin Wayne; Love, Kenner; Heidel, Richard D. (Virginia Cooperative Extension, 2009-05-01)
This publication will discuss control measures for many of the common weeds found in Virginia and West Virginia permanent fescue and mixed fescue, bluegrass, orchardgrass pastures and hayfields. In mixed grass, legume pastures and hayfields, selective removal of many problematic weed species is often not possible as most legumes will be killed after applications of broadleaf herbicides.
Crop and herbicide rotation effects on weed population dynamics and the characterization of imidazolinone-resistant smooth pigweed (Amaranthus hybridus)
Manley, Brian S. (Virginia Tech, 1996)
Shifts in weed populations to herbicide-resistant biotypes are occurring more frequently. In two adjacent field studies from 1991 through 1994, crop rotations and herbicide programs affected control and densities of common lambsquarters, common ragweed, smooth pigweed, redroot pigweed, jimsonweed, goosegrass, stinkgrass, large crabgrass, smooth crabgrass, fall panicum, and yellow nutsedge. Generally, the continuous use of the same herbicide or herbicides with similar selectivities resulted in proliferation of tolerant weed species. Corn, tomato, and soybean yields were affected mostly by crop rotations, rainfall, and weed control. Herbicide rotations or combinations must include herbicides that are efficacious on the target weed species to preclude weed shifts. Approximately 5 million smooth pigweed plants in Painter, VA were treated with imazethapyr or nicosulfuron from 1992 to 1994, and no ALS-inhibitor-resistant plants were identified. Smooth pigweed in Marion, MD and Oak Hall, VA, and livid amaranth in Warren County, NJ were reportedly escaping control from imazaquin or imazethapyr. In greenhouse studies, control of smooth pigweed from Marion and Oak Hall was 3 to 18% by 560 or 1120 g ai/ha imazaquin. Control of smooth pigweed from Painter was 81% by 70 g ai/ha imazethapyr. Control of livid amaranth from New Jersey was 8 to 15% by 560 g/ha imazethapyr. Field, greenhouse, and laboratory studies were conducted on Marion [resistant (R) biotype] and Painter [susceptible (S) biotype] smooth pigweed to characterize herbicide resistance in the R biotype. The R biotype was resistant at high levels to imazaquin and imazethapyr, and was cross-resistant at low levels to rmsulfuron and chlorimuron in the greenhouse. Both biotypes were equally susceptible to ASC-67040, CGA-152005, flumiclorac, halosulfuron, lactofen, metribuzin, nicosulfuron, pendimethalin, primisulfuron, pyrithiobac, and thifensulfuron in field or greenhouse studies. ALS enzyme assays confirmed target site-based resistance to imazaquin, imazethapyr, and rimsulfuron but not to chlorimuron in the R biotype. Metabolism of ¹⁴C-chlorimuron was more rapid in the R than in the S biotype which may explain the low level of whole plant resistance to chlorimuron in the R biotype. The occurrence of herbicide resistance and patterns of cross-resistance in weeds cannot be predicted.
Evaluation of florpyrauxifen-benzyl for use in pastures and hayfields
Greene, Wykle (Virginia Tech, 2021-12-07)
Weed control is a critical component in pastures and hayfields in order to ensure maximum forage yields. Typically, broadleaf weed control in pastures and hayfields is achieved through the use of synthetic auxin. However, these herbicides also control desirable broadleaf species such as forage legumes, including white clover. Use of herbicides can lead to severe injury and often complete elimination of white clover, making it difficult for producers to maintain legumes in mixed grass-legume swards while controlling weeds. It is often desirable to have legumes present in the sward due to their high nutritive forage value and ability to fix nitrogen compared to grass only swards. Florpyrauxifen-benzyl + 2,4-D is a new herbicide which is reported to control broadleaf weed species, while preserving white clover. Little published research exists on this herbicide, particularly for use in pastures and hayfields. Research evaluating sward composition indicates that florpyrauxifen-benzyl + 2,4-D is effective in controlling broadleaf weed species while also preserving greater amounts of white clover than any other herbicide treatments. Florpyrauxifen-benzyl + 2,4-D also resulted in significantly more forage grass production than the nontreated control. Florpyrauxifen-benzyl + 2,4-D was less effective than other herbicides when applied via fertilizer impregnation. Additional research assessing the spectrum of broadleaf weed control found that florpyrauxifen-benzyl + 2,4-D is a viable herbicide for the control of several broadleaf weed species including bulbous buttercup, Canada thistle, broadleaf plantain, plumeless thistle, and common ragweed. However, florpyrauxifen-benzyl + 2,4-D was less effective than other herbicides for controlling certain weeds, such as horsenettle. White clover was injured from florpyrauxifen-benzyl + 2,4-D, but was able to fully recover in 90 to 120 days. There were no differences in white clover response between the four varieties tested. When evaluating establishment of forage species, florpyrauxifen-benzyl + 2,4-D did not injure or reduce biomass of tall fescue or orchardgrass plantings, indicating a high level of safety. Florpyrauxifen-benzyl + 2,4-D was also safe to both drilled and frost seeded clover when applied prior to and at planting. Greenhouse trials revealed that flowering white clover is more sensitive to herbicides compared to vegetative white clover, and that safety of white clover to florpyrauxifen-benzyl + 2,4-D is dependent upon use rate. Considerations such as weed species present, and the amount of white clover injury that is considered acceptable will dictate the decision to utilize florpyrauxifen-benzyl + 2,4-D in pastures and hayfields. This research demonstrates the effectiveness and overall utility of florpyrauxifen-benzyl + 2,4-D for use in pastures and hayfields due to the effectiveness of weed species as well as the level of safety to white clover.
Evaluation of plant growth regulators for managing fescue turf along highway rights-of-way
Vollmer, Joseph Gerard (Virginia Polytechnic Institute and State University, 1989)
Plant growth regulators (PGR's) including metsulfuron plus mefluidide at 10 plus 140 g ha⁻¹, chlorsulfuron plus mefluidide at 20 plus 140 g ha⁻¹, imazethapyr plus imazapyr at 67.5 plus 2.5, 96.4 plus 3.6, and 115.7 plus 4.3 g ha⁻¹, ACP 2100 at 60, 120, and 180 g ha⁻¹, and DPX L5300 plus mefluidide at 10 plus 140, 20 plus 140, and 70 plus 140 g ha⁻¹ were applied to ‘KY 31’ tall fescue (Festuca arundinacea Schreb.). All rates of imazethapyr plus imazapyr, ACP 2100, and chlorsulfuron plus mefluidide afforded a significantly higher turf quality than metsulfuron plus mefluidide. ACP 2100 at 120 and 180 g ha⁻¹, imazethapyr plus imazapyr, DPX L5300 plus mefluidide at 70 plus 140 g ha⁻¹, and metsulfuron plus mefluidide gave the most consistent seedhead suppression. When treating seven month old tall fescue, DPX L5300 plus mefluidide did not adequately suppress seedhead elongation. Metsulfuron plus mefluidide, regardless of timing, caused excessive injury. All rates of imazethapyr plus imazapyr and the upper rates of ACP 2100 afforded the best turf quality followed by chlorsulfuron plus mefluidide in 1988 to ‘Rebel’ and both years to ‘KY 31’. Red fescue (Festuca rubra L.) quality was best with chlorsulfuron plus mefluidide and the high rate of DPX L5300 plus mefluidide. All other treatments resulted in a poorer quality turf. For all field studies on all turf types, in general, multiple applications were not practical and often caused excessive injury regardless of timing. Root studies conducted in the greenhouse revealed that with one application, imazethapyr plus imazapyr, ACP 2100, and DPX L5300 plus mefluidide provided root dry weights ranging from 0.5 to 0.7 g, which was greater than metsulfuron plus mefluidide, chlorsulfuron plus mefluidide, and the mowed check which afforded root dry weights of 0.1, 0.3, and 0.2, respectively. With two applications ACP 2100 and DPX L5300 plus mefluidide afforded 350, 1100, 200 and 200% greater root volume than metsulfuron plus mefluidide and chlorsulfuron plus mefluidide and 200, 630, 600 and 600% greater root dry weights. Three applications are not recommended. In laboratory studies using ‘KY 31’ tall fescue, mefluidide enhanced the uptake of ¹⁴C-DPX L5300 after 48 hours by as much as 11% and the translocation of ¹⁴C by 8.4% to the young leaves, 9.3% to the old leaves and 6.1% to the culm. Radioactive material concentrated in the tips of leaves. No significant accumulation of ¹⁴C occurred in the crown or roots.
Farm Security - Treat it Seriously. Security for plant agriculture: On farm assessment and security practices
Hagood, Edward S.; Hipkins, Patricia A. (Virginia Cooperative Extension, 2011)
How to implement farm security practices against possible terrorist acts.
Field and laboratory investigations on the efficacy, selectivity, and action of the herbicide clomazone
Vencill, William K. (Virginia Polytechnic Institute and State University, 1988)
Clomazone is a recently introduced herbicide for the selective control of grass and broadleaf weeds in soybeans. Field studies were conducted in full-season no-till soybeans to determine the efficacy of clomazone as a preplant and preemergence herbicide. Clomazone applied preemergence provided large crabgrass (Digitaria sanguinalis L.) control equivalent to that of oryzalin applied preplant or preemergence and provided better control of several broadleaf weeds. Control from preplant applications of clomazone was not adequate. Preemergence and preplant incorporated applications of clomazone were compared in conventionally-tilled soybeans. Clomazone efficacy at two depths of incorporation was also investigated. Clomazone applied preemergence generally provided control of large crabgrass and several broadleaf weed species equivalent to preplant incorporated applications. The addition of imazaquin or chlorimuron plus linuron improved smooth pigweed (Amaranthus hybridus L.) control over that provided by clomazone alone. These combinations generally did not improve large crabgrass, jimsonweed (Datura stramonium L.), and common lambsquarters (Chenopodium album L.) control over that of clomazone alone. Shallow incorporation (4 cm) of clomazone provided better weed control than deep incorporations (8 cm). Studies were conducted to evaluate efficacy and to quantify volatilization of three clomazone formulations (emulsifiable concentrate, wettable powder, and a microencapsulated formulation) following soil application. Samples were collected at the first, second, and tenth day after clomazone application. The three clomazone formulations provided control of large crabgrass. Clomazone volatilization was greatest 24 h after application from the emulsifiable concentrate and wettable powder formulations and declined at the second and tenth day after application. Volatilization from the microencapsulated formulation was lower than the other two formulations at all sampling times. Clomazone volatilization was greater from preemergence than preplant incorporated applications. Differential selectivity studies were initiated to determine the absorption, translocation, and metabolism of clomazone in tolerant soybean and smooth pigweed and susceptible redroot pigweed and livid amaranth exposed to foliar and root applied clomazone. Redroot pigweed and livid amaranth absorbed more clomazone through the roots than soybean and smooth pigweed. Absorption of foliar-applied clomazone was limited in all species. Of the clomazone absorbed in all species, most was translocated to the leaf tissue. Two metabolites of clomazone were found. One was determined to be a GS-clomazone conjugate. Differences in clomazone metabolism among species examined were not found. Growth and physiological responses of a normal hybrid ('DeKalb XL67'), a dwarf mutant, and an albino mutant of corn (Zea mays L.) to clomazone and interactions of gibberellin with clomazone on normal corn were examined. The dwarf mutant displayed greater tolerance to clomazone than normal corn. Growth measurements suggested that gibberellin was antagonistic with clomazone.
Field efficacy and availability, movement, and persistence of ICIA-0051 herbicide in soils
Wilson, John Samuel (Virginia Polytechnic Institute and State University, 1989)
Fields studies conducted in 1987 and 1988 determined the weed control efficacy of ICIA-0051 and SC-0774 in conventional and no-till systems of corn (Zea mays L.) culture. Results of the preemergence and postemergence applications of ICIA-0051, across all treatments after 8 weeks, showed 85% control or better of triazine-resistant smooth pigweed (Amaranthus hybridus L.), while fall panicum (Panicum dichotomiflorum Michx.) control ranged from 43 to 87%. Giant ragweed (Ambrosia trifida L.) control ranged from 30 to 95%, while control of ivyleaf morningglory (Ipomoea hederacea (L.) Jacq.) was below 75% in the preemergence treatments and ranged from 89 to 99% in the postemergence treatments. In general, the addition of atrazine to the pre- and postemergence treatments of ICIA-0051 improved weed control. SC-0774 treatments gave 85% or better control of fall panicum, but inadequate broadleaf weed control (75% or worse). Soil mobility studies using soil thin-layer chromatography and soil leaching columns indicated that the movement of ICIA-0051 was highly negatively correlated with the organic/humic matter fraction. Although the mobility patterns were similar, ICIA-0051 was more mobile than SC-0774, which was more mobile than atrazine. A comparison of ICIA-0051 across soils indicated that the order of mobility was Appling loamy sand (Rf = 6.4) > Davidson clay (Rf = 5.6) > Bojac sandy loam (Rf = 5.0) = Frederick silt loam (Rf = 4.9) > Hyde silty clay loam (Rf = 1.1). Other soil properties such as the clay content and pH were not strongly correlated with ICIA-0051 movement. Results of the adsorption/desorption studies indicated that the organic/humic matter fraction was primarily responsible for the binding and retention of ICIA-0051 across the five soils investigated. Based on the K constants derived from the Freundlich equation, the order of adsorption was Hyde > Frederick > Davidson = Bojac > Appling. The desorption results indicated that ICIA-005l was not tightly bound to the soil particles, with losses between 20 and 50% of the amount adsorbed after two desorptions. Results of the greenhouse persistence study, using mustard (Brassica kaber L.) as a bioassay species, indicated that ICIA-0051 was more biologically available than atrazine. Similar to the adsorption and leaching results, the persistence of ICIA-0051 was highly positively correlated with the soils’ organic matter. Regardless of the rate used, crop injury decreased over time, although the highest rate (1 ppm of ICIA-0051) showed significant crop injury even after 6 months in several soils in the greenhouse studies.
Field, greenhouse, and laboratory evaluation of the efficacy and selectivity of the herbicide thifensulfuron for weed control in soybeans (Glycine max)
Walker, Lewis Meriwether (Virginia Tech, 1991)
Thifensulfuron is a new herbicide of the sulfonylurea class under development by E. I. Dupont de Nemours Company Inc. for postemergence broadleaf weed control in soybeans [Glycine max (L.) Merr]. Field studies evaluated the influence of adjuvants and chlorimuron upon the efficacy of thifensulfuron. Thifensulfuron applied alone provided smooth pigweed (Amaranthus hybridus L. #AMACH) control at application rates 12% of those of the similar herbicide chlorimuron. Nonionic surfactant or crop oil concentrate increased soybean sensitivity to thifensulfuron, but an adjuvant was required to obtain consistent seedling common lambsquarters (Chenopodium album L. #CHEAL) control. Chlorimuron and thifensulfuron combinations did not control ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. #IPOHE]. Greenhouse studies evaluated soybean cultivar sensitivity to thifensulfuron. Seven popular Virginia soybean varieties and one national variety (Williams 82) were screened for tolerance to thifensulfuron. Differences in varietal sensitivity was verified. Soybean varieties Vance, Essex, Hutcheson, and York proved to be more sensitive to 9.1 g ha⁻¹ thifensulfuron than FFR 561, Williams 82, or Deltapine 105. No relationship between sensitivity to thifensulfuron and Essex parentage could be drawn. The selectivity of the sulfonylurea class of herbicides is reportedly based on differential metabolism of the herbicide between sensitive and tolerant weed and crop species. Laboratory studies were conducted utilizing thifensulfuron-sensitive and tolerant weed species, velvetleaf (Abutilon theophrasti Medic. #ABUTH) and spurred anoda [Anoda cristata (L.) Schlecht #ANVCR], respectively, as well as the relatively tolerant Williams 82 and sensitive Vance soybean. Absorption and distribution studies indicated that all species absorbed and translocated similar amounts of ¹⁴C 1, 3, and 5 days after application of the methyl ester of [¹⁴C-thiophene] thifensulfuron. Metabolism studies indicated that both tolerant spurred anoda and sensitive velvetleaf metabolized thifensulfuron at similar rates 3 days after treatment. Metabolism appears to be the major mechanism for the selectivity of thifensulfuron to soybeans. The mechanism for spurred anoda tolerance to thifensulfuron has yet to be determined. This research indicates that broadcast foliar applications of 4.5 g ha⁻¹ thifensulfuron with 0.125% v/v nonionic surfactant or 1% v/v crop oil concentrate can provide selective postemergence smooth pigweed and common lambsquarters control for soybean production in Virginia. Caution should, however, be taken in prescribing greater than 4.5 g ha⁻¹ thifensulfuron due to the variability in cultivar sensitivity to thifensulfuron.
Field, greenhouse, and laboratory studies on the efficacy and action of the herbicides SC-0051 and SC-0774
Mayonado, David James (Virginia Polytechnic Institute and State University, 1988)
SC-0051 and SC-0774 are two experimental herbicides of undisclosed chemistry. A three year field study was conducted to evaluate SC-0051 and SC-0774 for weed control in conventional and no-till corn in Virginia. SC-0051 applied preemergence or postemergence, controlled common lambs-quarters (Chenopodium album L.), common ragweed (Ambrosia artemisiifolia L.) horseweed (Conyza canadensis (L.) Cronq.), common chickweed (Stellaria media (L.) Vill. and was safe to corn. SC-0051 did not control smooth pigweed (Amaranthus hybridus L.) or giant foxtail (Setaria faberi Herrm.). SC-0774 effectively controlled the rye (Secale cereale) cover crop and large crabgrass (Digitaria sanguinalis (L. Scop.) but did not control broadleaf weeds or giant foxtail. SC-0774 also caused considerable but temporary corn injury when applied at rates above 1.1 kg/ha. Combinations of SC-0051 and atrazine provided broad spectrum weed control and yields comparable to atrazine plus metolachlor. Field and laboratory studies were conducted to evaluate the effect of soil pH on the soil mobility of SC-0051 and SC-0774 in sandy loam soils. SC-0774 was applied to soils amended to high and low pH and samples were collected by depth throughout the growing season. A method was developed for extracting and quantifying SC-0774 from collected soil samples. Large crabgrass was also used as a bioindicator species for qualitative detection of SC-0774 residues. These studies showed that SC-0774 was significantly more mobile in high pH soil than in low pH soil. Also, the decreased mobility of SC-0774 at low soil pH lead to decreased corn injury but it increased the soil residual activity of this herbicide. Soil column studies with SC-0774 and SC-0051 showed that the soil mobility of both herbicides increased with increasing soil pH. These herbicides cause reductions in chlorophyll and carotenoid levels in susceptible species resulting in a bleached appearance. The mechanism of this bleaching action is not known. Studies were conducted which examined the effect of SC-0051 on the pigment content and quantity in the susceptible species soybean. High performance liquid chromatography was used to separate, quantify, and identify pigments present in extracts of bleached tissues. The bleaching herbicide norflurazon was also examined for comparison purposes. SC-0051 and norflurazon inhibited the biosynthesis of carotenoids while causing an accumulation of the carotene precursor phytoene and an additional, unidentified pigment that appears to be structurally related to phytoene. This indicates that SC-0051, like norflurazon, inhibits carotenoid formation by blocking the desaturation of phytoene to phytofluene. The uptake and translocation of ¹⁴C-SC-0051 into tolerant corn and susceptible soybean seedlings was examined under growth chamber conditions to investigate the basis for the selectivity of this herbicide. Herbicide uptake was similar in both species but the susceptible soybean translocated a higher percentage of the ¹⁴C-SC-0051 to the growing point of new tissues than did the tolerant corn. It is proposed that differential translocation plays a role in the crop selectivity of the herbicide SC-0051.
Fine Tuning a Sprayer with "Ounce" Calibration Method
Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2009-05-01)
Guidelines to quickly evaluate the performance of a sprayer. Sprayer calibration, nozzle discharge, spray pattern uniformity, speed checks, pump performance and plumbing arrangements are evaluated with minimal calculations.
Fine tuning a sprayer with ounce calibration method
Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2001)
This extension publication discusses guidelines to quickly evaluate the performance of a sprayer. Sprayer calibration, nozzle discharge, spray pattern uniformity, speed checks, pump performance and plumbing arrangements are evaluated with minimal calculations.
Growing Bread Wheat in the Mid-Atlantic Region
Thomason, Wade E.; Griffey, Carl A.; Alley, Marcus M.; Phillips, Steven B.; Stromberg, Erik L.; Herbert, D. Ames Jr.; Hagood, Edward S. (Virginia Cooperative Extension, 2019-03-20)
Discusses growing bread wheat in the Mid-Atlantic Region, including wheat varieties best suited for the region, cultivar selection, seeding schedules, fertilizers, weed control, disease management, and harvest.
Growing Hulless Barley in the Mid-Atlantic
Thomason, Wade E.; Griffey, Carl A.; Alley, Marcus M.; Phillips, Steven B.; Hagood, Edward S.; Herbert, D. Ames Jr.; Stromberg, Erik L. (Virginia Cooperative Extension, 2019-03-20)
Discusses growing varieties of hulless barley in the Mid-Atlantic Region. Discusses cultivar selection, seeding schedules, fertilizers, insect, disease and weed management and control, and harvest.
Herbicide combinations for establishing no-till soybeans (Glycine max) with an emphasis on the use of chlorimuron
Moseley, Carroll (Virginia Tech, 1990)
In full-season-soybean weed management experiments, the addition of glyphosate [N-(phosphonomethyl)glycine], paraquat (1,1'-dimethyl-4,4'-bipyridinium ion), or HOE-0661 [ammonium (3-amino-3-carboxypropyl)methylphosphinate] to chlorimuron [2-[[[[(4-chloro-6-methoxy-2-pyrimidinyl)amino] carbonyl]amino]sulfonyl] benzoic acid] plus linuron [N'- (3,4-dichlorophenyl)-N-methoxy-N-methyl urea] was required for effective weed control, especially of eastern black nightshade (Solanum ptycanthum Dun.). In double-crop experiments over 4 years including 10 experimental sites and 8 different weeds, chlorimuron plus linuron provided good control of vegetation at planting and residual weed control without glyphosate, paraquat, or HOE-0661. Cyanazine [2-[[4-chloro-6-(ethylamino)-1,3,5-triazin- 2-yl]amino]-2-methylpropanenitrile] and 2,4-D [(2,4- dichlorophenoxy)acetic acid] were the most effective herbicides for horseweed (Conyza canadensis (L.)Cronq.) control prior to establishing full-season no-till soybeans (Glycine max (L.)Merr.). In greenhouse experiments, emergence of tobacco (Nicotiana tabacum L.) seedlings was severely inhibited by all chlorimuron-containing treatments and by the highest rates of imazaquin [2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-3-quinolinecarboxylic acid]. Growth of tobacco transplanted into a treated potting mixture was severely reduced by all rates of chlorimuron-containing herbicides, and to a lesser extent by imazaquin. Postemergence applications of chlorimuron alone or imazaquin did not significantly affect tobacco growth. In the greenhouse, 'Vance' and 'Forrest' soybean varieties were more sensitive to chlorimuron than were 'W-20' (a sulfonylurea-resistant variety), 'Essex', or 'Hutcheson'. Herbicide injury increased with increasing soil pH. Under simulated rainfall conditions, chlorimuron movement in soil increased with increasing pH and rainfall. Soybean injury may be more directly related to chlorimuron in the soil water solution than to the amount of chlorimuron present in the soil profile. Laboratory experiments indicated that tolerance of pitted (Ipomoea lacunosa L.) and entire leaf (Ipomoea hederacea var. integriuscula Gray) morningglories to chlorimuron may be due to reduced herbicide uptake. Sensitivity of 'Vance' soybeans may be associated with the inability to rapidly metabolize chlorimuron herbicide.
High Residue Cover Crops for Annual Weed Suppression in Corn and Soybean Production and Potential for Hairy Vetch (Vicia villosa) to be Weedy
Pittman, Kara (Virginia Tech, 2018-02-07)
After termination, cover crop residue can suppress weeds by reducing sunlight, decreasing soil temperature, and providing a physical barrier. Experiments were implemented to monitor horseweed suppression from different cover crops as well as two fall-applied residual herbicide treatments. Results suggest that cover crops, other than forage radish in monoculture, can suppress horseweed more consistently than flumioxazin + paraquat or metribuzin + chlorimuron-ethyl. Cover crop biomass is positively correlated to weed suppression. Subsequent experiments were designed to determine the amount of weed suppression from different cover crop treatments and if carbon to nitrogen (C:N) ratios or lignin content are also correlated to weed suppression or cover crop residue thickness. Results indicate that cereal rye alone and mixtures containing cereal rye produced the most biomass and suppressed weeds more than hairy vetch, crimson clover, and forage radish alone. Analyses indicate that lignin, as well as biomass, is an important indicator of weed suppression. While cover crops provide many benefits, integrating cover crops into production can be difficult. Hairy vetch, a legume cover crop, can become a weed in subsequent seasons. Multiple experiments were implemented to determine germination phenology and viability of two hairy vetch cultivars, Groff and Purple Bounty, and to determine when viable seed are produced. Almost all germination occurred in the initial cover crop growing season for both cultivars. Both cultivars had <1% of viable seed at the termination of the experiment. These results indicate that seed dormancy is not the primary cause of weediness.
Identification and Control of Annual Ryegrass in No-Till Corn in Virginia
King, Steve Russell; Hagood, Edward S.; Bradley, Kevin Wayne (Virginia Cooperative Extension, 2009-05-01)
This publication reviews the identification and control of annual ryegrass in no-till corn in Virginia.
Identification and Control of Hemp Dogbane (Apocynum cannabinum L.) in Virginia
Bradley, Kevin Wayne; Hagood, Edward S. (Virginia Cooperative Extension, 2009-05-01)
This publication reviews the identification and control of Hemp Dogbane (Apocynum cannabinum L.) in Virginia.

Browsing by Author "Hagood, Edward S."

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