Progress 01/01/03 to 12/31/07
Outputs
OUTPUTS: Research demonstrated that the combination of chlorsulfuron plus flucarbazone-sodium was as efficacious as mesosulfuron or pinoxaden for the control of diclofop-susceptible ryegrass in wheat and barley, and that wheat and barley tolerance to this treatment was excellent. The experimental herbicide KIH-485, as well as flufenacet, continued to demonstrate excellent preemergence efficacy on diclofop-resistant ryegrass in small grains. Research showed that the use of glyphosate (Roundup) in glyphosate-tolerant corn hybrids is the only efficacious registered control alternative for resistant shattercane, although one experimental preemergence compound was also shown to be efficacious. Continued research demonstrated reduced sensitivity to glyphosate in common lambsquarters plants grown from seed obtained from collections made in Westmoreland County, Virginia. Responses to glyphosate were observed to be normally distributed among 15 F2 lines from both Westmoreland and wild type sources. I50 estimates for fresh weight reduction across lines for these sources were 0.91 and 0.32 kg ae/ha of glyphosate, respectively. Field and greenhouse evaluations failed to confirm suspected reduced sensitivity to glyphosate in a Westmoreland County johnsongrass collection. Virginia agronomic crop producers, extension agents, and agriservice professionals have been fully apprised of the results of this research and appropriate production recommendations derived from same. PARTICIPANTS: One PhD and one M.S. student participated in the research covered by this report. TARGET AUDIENCES: Virginia agronomic crop producers, Extension Agents, and agriservice professionals were fully apprised of the results of this research and production recommendations derived from same. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Efficacious and cost-effective control of diclofop-resistant ryegrass was observed with mesosulfuron, pinaoxaden, and chlorsufuron plus flucarbazone-sodium. The registration of preemergence materials, however, will represent a significant improvement in ability to manage severe infestations of diclofop-resistant ryegrass. Requests for expedited registration of KIH-485 and flufenacet for preemergence control of diclofop-resistant ryegrass in small grains were submitted to the respective manufacturers. These registrations would also afford an important alternative mode of action with regard to resistance management. At this time, impact on production agriculture from common lambsquarters with reduced glyphosate sensitivity is minimal. The potential impact, however, of the spread of biotypes of this weed species with reduced sensitivity is substantial. Similarly, the impact of ALS-resistant shattercane has been minimal, although the need to treat these infestations with glyphosate in glyphosate-tolerant corn as the only other efficacious treatment will continue to increase reliance on this herbicide. This reliance on glyphosate is problematic given the increasing development of glyphosate-resistant and glyphosate-tolerant weed species.
Publications
- King, Steven R., Ronald R. Ritter, Edward S. Hagood, Jr., and Hiwot Menbere. 2007. Control of ALS-Resistant Shattercane (Sorghum bicolor) in Field Corn (Zea mays) with KIH-485. Weed Technol. 27:578-582.
- Hite, Grace A., Steven R. King, and Edward S. Hagood. 2007. Response of Selected Virginia Common Lambsquarters (Chenopodium album) Biotypes to Glyphosate. Weed Sci. Soc Am. Abstr. 47: 22.
- King, S.R. and E.S. Hagood, Jr. 2006. Herbicides for the Control of ALS-Resistant Shattercane (Sorghum bicolor) in Corn (Zea mays). Weed Technol. 20:416-421.
- Hite, G.A., S.R. King, E.S. Hagood, and G.I. Holtzman. 2008. Differential Response of a Virginia Common Lambsquarters (Chenopodium album) Collection to Glyphosate. Weed Sci. 56: 203-209.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Research demonstrated that the combination of chlorsulfuron plus flucarbazone-sodium was as efficacious as mesosulfuron or pinoxaden for the control of diclofop-susceptible ryegrass in wheat and barley, and that wheat and barley tolerance to this treatment was excellent. The experimental herbicide KIH-485, as well as flufenacet, continued to demonstrate excellent preemergence efficacy on diclofop-resistant ryegrass in small grains. Continued research demonstrated reduced sensitivity to glyphosate in common lambsquarters plants grown from seed obtained from collections made in Westmoreland County, Virginia. Responses to glyphosate were observed to be normally distributed among 15 F2 lines from both Westmoreland and wild type sources. I50 estimates for fresh weight reduction across lines for these sources were 0.91 and 0.32 kg ae/ha of glyphosate, respectively. Field and greenhouse evaluations failed to confirm suspected reduced sensitivity to glyphosate in a Westmoreland
County johnsongrass collection.
TARGET AUDIENCES: Virginia agronomic crop producers, extension agents, and agriservice professionals.
Impacts
Efficacious and cost-effective control of diclofop-resistant ryegrass was observed with mesosulfuron, pinaoxaden, and chlorsufuron plus flucarbazone-sodium. The registration of preemergence materials, however, will represent a significant improvement in ability to manage severe infestations of diclofop-resistant ryegrass. Requests for expedited registration of KIH-485 and flufenacet for preemergence control of diclofop-resistant ryegrass in small grains were submitted to the respective manufacturers. These registrations would also afford an important alternative mode of action with regard to resistance management. At this time, impact on production agriculture from common lambsquarters with reduced glyphosate sensitivity is minimal. The potential impact, however, of the spread of biotypes of this weed species with reduced sensitivity is substantial.
Publications
- Hite, G.A., S.R. King, E.S. Hagood, and G.I. Holtzman. 2008. Differential Response of a Virginia Common Lambsquarters (Chenopodium album) Collection to Glyphosate. Weed Sci. 56:(In press).
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Progress 10/01/05 to 09/30/06
Outputs
Research demonstrated that pinoxaden was as efficacious as mesosulfuron for the control of diclofop-susceptible ryegrass in wheat, and that barley tolerance to pinoxaden was superior to tolerance to mesosulfuron. Continued investigations will be required to ascertain the efficacy of pinoxaden in heavily homogeneous diclofop-resistant ryegrass infestations. The experimental preemergence herbicide KIH-485 continued to demonstrate excellent efficacy on diclofop-resistant ryegrass in small grains, and well as on ALS-resistant shattercane in field corn. Research demonstrated reduced sensitivity to glyphosate in common lambsquarters plants grown from seed obtained from a second group of collections made in 2004 at the Westmoreland County site of the original 2002 collection. To describe population responses, 360 F2 seedlings from Westmoreland 2004 source plants and wild type plants were treated with sequential glyphosate applications of 0.56, 1.68, and 2.24 kg ai/ha at
three week intervals. In the least susceptible 2004 Westmoreland line, vigor reduction averaged 36 percent at three weeks following the third application, and no mortality was observed among the 360 plants. In the wild type, however, vigor reduction averaged over 99 percent, with 98 percent mortality.
Impacts
In 2006, the second year of use of mesosulfuron, efficacious and cost-effective control of diclofop-resistant ryegrass continued to be observed. Glyphosate continued to be used in glyphosate-tolerant corn hybrids for the control of ALS-resistant shattercane on essentially all corn acreage where this resistant species has been confirmed. A request for expedited registration of KIH-485 for preemergence control of both diclofop-resistant ryegrass in small grains and ALS-resistant shattercane in field corn was submitted to the manufacturer. This registration would afford an important alternative mode of action with regard to resistance management. Significant differential response to sequential glyphosate applications was confirmed in F2 populations of common lambsquarters plants derived from additional seed collections. The infestation pattern of common lambsquarters with reduced sensitivity to glyphosate was monitored. One additional site exhibiting reduced glyphosate
sensitivity was reported in 2006. At this time, impact on production agriculture is minimal. The potential impact, however, of the spread of biotypes of this weed species with reduced sensitivity to glyphosate is substantial.
Publications
- King, Steven R., Ronald R.Ritter, Edward S. Hagood, Jr., and Hiwot Menbere. 2007. Control of ALS-Resistant Shattercane (Sorghum bicolor) in Field Corn (Zea mays) with KIH-485. Weed Technol. 27:(In Press).
- Hite, Grace A., Steven R. King, and Edward S. Hagood. 2007. Response of Selected Virginia Common Lambsquarters (Chenopodium album) Biotypes to Glyphosate. Weed Sci. Soc Am. Abstr. 47:(In Press).
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Progress 10/01/04 to 09/30/05
Outputs
Research demonstrated that mesosulfuron is efficacious for the control of diclofop-resistant ryegrass in wheat. One experimental postemergence herbicide was also observed to be efficacious for control of this species, and was observed to be safe for use in barley as well as wheat. Preemergence treatments of pedimethalin, flufenacet, and an experimental compound also afforded excellent control of resistant ryegrass. Of all of the herbicide resistant crop/herbicide systems evaluated, glyphosate in Roundup Ready corn was most efficacious for the control of ALS-resistant shattercane. The use of a preemergence experimental compound in addition to glyphosate continued to afford best control of this species. Research demonstrated reduced sensitivity to glyphosate in common lambsquarters plants grown from seed obtained from a second group of collections made in 2004 at the site of the original 2002 collection.
Impacts
In 2005, the initial year of use of mesosulfuron, efficacious and cost-effective control of diclofop-resistant ryegrass was observed. Glyphosate continued to be used in glyphosate-tolerant corn hybrids for the control of ALS-resistant shattercane on essentially all corn acreage where this resistant species has been confirmed. However, the experimental preemergence herbicide continued to be demonstrated to be efficacious. Its registration would afford an alternative with regard to resistance management. Differential response to glyphosate was confirmed in 2005 in common lambsquarters plants derived from additional seed collections. The infestation pattern of common lambsquarters with reduced sensitivity to glyphosate was monitored. At this time, impact on production agriculture is minimal. The potential impact, however, of the spread of a biotype of this weed species with reduced sensitivity to glyphosate is substantial.
Publications
- King, S. R. and E.S. Hagood, Jr. 2005. Effect of Additives and Small Grain Herbicides on the Efficacy of AE F130060 plus AE F107892 in Barley. Weed Technol. 19:372-379.
- King, S.R. and E.S. Hagood, Jr. 2005. Herbicides for the Control of ALS-Resistant Shattercane (Sorghum bicolor) in Corn (Zea mays). Weed Technol. 19:(In press).
- King, S.R., E.S. Hagood, Jr, and P.L. Hipkins. 2005. Herbicides for the Control of ALS-Resistant Shattercane in Corn. Proc. Weed Sci. Soc. of Am. 45:14.
- King, S.R., R.L. Ritter, E.S. Hagood. and H. Menbere. 2005. Control of Sorghum Species in Field Corn with KIH-485. Proc. Northeast. Weed Sci. Soc. 59: (In press).
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Progress 10/01/03 to 09/30/04
Outputs
Effective control measures for diclofop-resistant Italian ryegrass (Lolium multiflorum) in small grains were identified through field, greenhouse and laboratory research. Osprey (mesosulfuron) was shown to afford excellent ryegrass control with postemergence applications, and will be labeled for 2004-05. Shattercane (Sorghum bicolor) with resistance to ALS-inhibiting herbicides was identified in the Shenandoah Valley and Northern Piedmont regions of Virginia. Research showed that the use of glyphosate (Roundup) in glyphosate-tolerant corn hybrids is the only efficacious registered control alternative for resistant shattercane, although one experimental preemergence compound was also shown to be efficacious. A common lambsquarters (Chenopodium album) biotype with reduced sensitivity to glyphosate was identified in a field in Westmoreland County, Virginia in 2002 and confirmed in 2004. Greenhouse evaluations revealed significant reductions in sensitivity in an F2
generation of progeny from the Westmoreland biotype compared to the wild type, where control was 61 and 99 percent, respectively, following three glyphosate applications totaling 4.0 lbs ai/acre (4.48 kg ai/ha).
Impacts
This year's registration of mesosulfuron (Osprey) will allow a more efficacious control alternative for diclofop-resistant ryegrass. Glyphosate was used in glyphosate-tolerant corn hybrids for the control of ALS-resistant shattercane on essentially all corn acreage where this resistant species has been confirmed. However, the experimental preemergence herbicide also provides control, and would afford an alternative with regard to resistance management. The infestation pattern of common lambsquarters with reduced sensitivity to glyphosate was monitored. At this time, impact on production agriculture is minimal. The potential impact, however, of the spread of a biotype of this weed species with reduced sensitivity to glyphosate is substantial.
Publications
- King, S.R. and E.S. Hagood, Jr. 2003. The effect of rate and timing of AEF130060 plus AEF107892 for the control of Italian ryegrass (Lolium multiflorum) in barley (Hordeum vulgare). Weed Technol. 17:866-870.
- King, S.R., E.S. Hagood, Jr., K.W. Bradley, and K.K. Hatzios. 2003. Absorption, translocation, and metabolism of AEF130060 in wheat, barley, and Italian ryegrass with or without dicamba. Weed Sci. 51:509-514.
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Progress 10/01/02 to 09/30/03
Outputs
Effective control measures for diclofop-resistant Italian ryegrass (Lolium multiflorum) in small grains were identified through field, greenhouse and laboratory research. Osprey (mesosulfuron) was shown to afford excellent ryegrass control with postemergence application. Flufenacet plus metribuzin (Axiom)also provided good ryegrass control with preemergence application when timely activation rainfall was received. Shattercane (Sorghum bicolor) with resistance to ALS-inhibiting herbicides was identified in the Shenandoah Valley and Northern Piedmont regions of Virginia. Research showed that the use of glyphosate (Roundup) in glyphosate-tolerant corn hybrids is the only efficacious control alternative for resistant shattercane. A common lambsquarters (Chenopodium album) biotype with reduced sensitivity to glyphosate was identified in a field in Westmoreland County, Virginia. Greenhouse evaluations revealed significant reductions in sensitivity in F1 and F2 generations
of progeny compared to a wild type from Montgomey County, Virginia.
Impacts
Flufenacet plus metribuzin will be available under Section 18 Emergency registration for Italian ryegrass control on 50,000 acres of Virginia wheat. The registration of mesosulfuron will allow a more efficacious control alternative for this weed. Glyphosate was used in glyphosate-tolerant corn hybrids for the control of ALS-resistant shattercane on essentially all corn acreage where this resistant species has been confirmed. The infestation pattern of common lambsquarters with reduced sensitivity to glyphosate will be monitored, and research on alternative control measures conducted, to prevent this species from becoming a major constraint to production.
Publications
- King, S.R. and E.S. Hagood, Jr. 2003. The effect of rate and timing of AEF130060 plus AEF107892 for the control of Italian ryegrass (Lolium multiflorum) in barley (Hordeum vulgare). Weed Technol. 17: (In press)
- King, S.R., E.S. Hagood, Jr., K.W. Bradley, and K.K. Hatzios. 2003. Absorption, translocation, and metabolism of AEF130060 in wheat, barley, and Italian ryegrass with or without dicamba. Weed Sci. 51: (In press)
- King, S.R., E.S. Hagood, Jr., K.W. Bradley, and K.K. Hatzios. 2003. Absorption, translocation, and metabolism of AEF130060 in wheat, barley, and Italian ryegrass with or without dicamba. Proc. Weed Sci. Soc. of Am. 43:39.
- King, S.R. and E.S. Hagood, Jr. 2003. Efficacy of AEF130060 plus AEF107892 for the control of Italian ryegrass in barley. Proc. Northeast. Weed Sci. Soc. 57:13.
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