SAES-422 Multistate Research Activity Accomplishments Report
Sections
Status: Approved
Basic Information
- Project No. and Title: NC226 : Development of Pest Management Strategies for Forage Alfalfa Persistence
- Period Covered: 10/01/2001 to 09/01/2002
- Date of Report: 05/12/2003
- Annual Meeting Dates: 02/25/2003 to 02/26/2003
Participants
[Minutes]
Accomplishments
Objective 1. To Elucidate Mechanisms By Which Biotic Agents Interact With Abiotic Factors to Limit Stand Persistence of Forage Alfalfa
Results from Ohio and Indiana indicate that death of alfalfa plants is primarily occurring during the growing season instead of over winter. This is in sharp contrast to the generally accepted belief that winter killing is the primary reason alfalfa stands decline over time. Ohio data indicates that pathogenic fungi (Fusarium spp.) may contribute to stand decline in summer. Indiana data show that nutrient imbalance (high P levels without K fertilization) accelerates stand decline. Starch, protein and amino acid concentrations are lower in roots of plants grown in high-P soils without K fertilizer. Low levels of these root reserves may be contributing to poor alfalfa persistence.
Objective 2. To Enhance Alfalfa Persistence Through Improved Plant Resistance to Key Pests by Conventional Breeding and Genetic Engineering Approaches
A total of five states reported on studies examining the potential of plant resistance to key pests in alfalfa, including Maryland, Michigan, Minnesota, Ohio, Virginia, and Wyoming. The majority of the studies tested the efficacy of newer glandular-haired, potato leafhopper resistant alfalfa cultivars. Virginia, using the second-generation glandular-haired variety Pioneer 54H69, continued to observe no differences in PLH densities between the resistant variety and a susceptible cultivar. In contrast, other states reported clear-cut differences. Michigan continued with a variety trial that included resistant varieties and found two PLH-resistant lines with higher yields than the check under increased PLH populations. Ohio, in large plot studies using a recently released variety, Pioneer 54H91, found significant reductions in both PLH adult and nymph densities. They showed that insecticide treatment, while justified for a susceptible cultivar 7 of 8 summer harvests, was justified for the resistant cultivar only 3 of the 8 times. Maryland began field studies also using this newer line, 54H91, and found that during one harvest with heavier PLH pressure, that there was a significant reduction in yield with the susceptible cultivar compared with no yield loss in the resistant variety. Virginia also reported on infestations of alfalfa weevil in their plots with PLH-resistant cultivars. Variety had no effect on densities of alfalfa weevil. Overall, results from numerous locations are demonstrating the improvement in the PLH-resistant cultivars.
Minnesota continued studies on the impact of possible resistant sources, including glandular-haired cultivars, on the alfalfa blotch leafminer, Agromyza frontella. They did not discern any significant differences in the percentage of stems with at least one trifoliolate damaged by the leafminer. They concluded that with the lack of resistance against the leafminer (and also poor insecticide performance), there is a need for greater work with beneficial parasitoids for a promising control strategy.
Wyoming reported on resistance for plant diseases. They have continued to develop selection and breeding methods for increasing resistance to brown root rot, Phoma slerotioides. This effort has resulted in an increase in brown root rot resistance in half-sib family lines compared to their parent variety. Progress is also being made toward the development of a standard protocol for evaluating alfalfa lines for resistance to brown root rot.
Ohio reported on a multi-state effort to evaluate performance of alfalfa varieties developed across six decades. Results suggest forage yield has increased over the past five decades, and that improvements in disease resistance are correlated with the higher yields and stand density as alfalfa stands age.
Objective 3. To Identify and Enhance Biological and Cultural Control Measures that Reduce Pest Populations and Improve Forage Alfalfa Persistence
Two states conducted research on biological and cultural control of insects in alfalfa during 2002. Virginia compared densities of natural enemies in treated and untreated glandular-haired and non-glandular-haired alfalfa at two sites. B. anurus represented 97% and 99% of the total parasitoids collected at the Piedmont and southwestern sites, respectively. Variety had no effect on rates of parasitization at either site nor did spray regime at the southwestern site despite reduced populations of AW larvae in treated plots. A sample date by spray regime interaction was found at the Piedmont site in 2002. However, the effect of spray regime on each sample date revealed no significant differences in rates of parasitization between spray regimes. Thus, glandular trichomes on 54H69 did not appear to impede overall biological control of AW larvae by Bathyplectes spp. females. Variety had no effect on rates of fungal infection by Z. phytonomi at the southwestern site. A sample date by variety interaction was significant for rates of fungal infection at the Piedmont site. However, the effect of variety on each sample date revealed no significant differences in rate of fungal infection between varieties.
Minnesota scientists evaluated two European parasitoid species released in Ontario during the late 1970‘s to control alfalfa blotch leafminer, Agromyza frontella. In 1999, both D. dryas and C. liriomyzae were parasitizing first-generation A. frontella in Ontario. The combined parasitism rate for both species as revealed by larval dissections was 97.5% by the end of the first A. frontella generation. Of the adult parasitoids reared, 86% were D. dryas and 14% were C. liriomyzae. By the end of the first A. frontella generation, 86% of parasitized hosts contained at least one unencapsulated parasitoid and could therefore produce an adult parasitoid, and 12% of parasitized hosts escaped parasitism by containing only encapsulated parasitoids. The sex ratio of D. dryas was even at emergence, but strongly female-biased in sweep samples from the field. Egg loads of D. dryas females were all greater than zero and as high in the field as our highest laboratory estimates, suggesting that egg availability does not limit fitness under the conditions that we observed in the field.
Objective 4. To Integrate Control Measures with Decision-Making Guidelines
for Adoption by Specific States/Regions
Two states provided reports on Objective 4. In Maryland, a web site, Potato Leafhopper as a Pest of Alfalfa, is being developed in conjunction with leafhopper specialists. The site focuses on identification, biology, and management of the insect. This effort is intended as a model for the development of other pest web sites as part of NC-226. In Michigan, patterns of potato leafhopper densities were determined within two alfalfa fields to test for optimum scouting protocols. They determined that intensive sampling is not economically feasible, thus decision-making is best conducted on a whole field basis instead of on a treatment zone basis.
Usefulness of Findings
The overall goal of the multistate project is to address a critical concern of farmers: the significant reduction in alfalfa stand life caused by pests and other factors. The lack of persistence significantly reduced profit associated with alfalfa, the principal forage component of a wide variety of agricultural production and conservation systems. In addition, the project plans to use the web site as a means to extend current information on the status of alfalfa pests and their management.
Work Planned for Next Year
Research will continue on each objective. Some of the original field studies are now focusing on the more critical final years during the lifespan of an alfalfa stand. An outline for a synthesis publication on integrating concepts of alfalfa persistence has been prepared, and work on this publication will continue during 2003. In addition, the website will be expanded to provide pest information beyond potato leafhopper.
Results from Ohio and Indiana indicate that death of alfalfa plants is primarily occurring during the growing season instead of over winter. This is in sharp contrast to the generally accepted belief that winter killing is the primary reason alfalfa stands decline over time. Ohio data indicates that pathogenic fungi (Fusarium spp.) may contribute to stand decline in summer. Indiana data show that nutrient imbalance (high P levels without K fertilization) accelerates stand decline. Starch, protein and amino acid concentrations are lower in roots of plants grown in high-P soils without K fertilizer. Low levels of these root reserves may be contributing to poor alfalfa persistence.
Objective 2. To Enhance Alfalfa Persistence Through Improved Plant Resistance to Key Pests by Conventional Breeding and Genetic Engineering Approaches
A total of five states reported on studies examining the potential of plant resistance to key pests in alfalfa, including Maryland, Michigan, Minnesota, Ohio, Virginia, and Wyoming. The majority of the studies tested the efficacy of newer glandular-haired, potato leafhopper resistant alfalfa cultivars. Virginia, using the second-generation glandular-haired variety Pioneer 54H69, continued to observe no differences in PLH densities between the resistant variety and a susceptible cultivar. In contrast, other states reported clear-cut differences. Michigan continued with a variety trial that included resistant varieties and found two PLH-resistant lines with higher yields than the check under increased PLH populations. Ohio, in large plot studies using a recently released variety, Pioneer 54H91, found significant reductions in both PLH adult and nymph densities. They showed that insecticide treatment, while justified for a susceptible cultivar 7 of 8 summer harvests, was justified for the resistant cultivar only 3 of the 8 times. Maryland began field studies also using this newer line, 54H91, and found that during one harvest with heavier PLH pressure, that there was a significant reduction in yield with the susceptible cultivar compared with no yield loss in the resistant variety. Virginia also reported on infestations of alfalfa weevil in their plots with PLH-resistant cultivars. Variety had no effect on densities of alfalfa weevil. Overall, results from numerous locations are demonstrating the improvement in the PLH-resistant cultivars.
Minnesota continued studies on the impact of possible resistant sources, including glandular-haired cultivars, on the alfalfa blotch leafminer, Agromyza frontella. They did not discern any significant differences in the percentage of stems with at least one trifoliolate damaged by the leafminer. They concluded that with the lack of resistance against the leafminer (and also poor insecticide performance), there is a need for greater work with beneficial parasitoids for a promising control strategy.
Wyoming reported on resistance for plant diseases. They have continued to develop selection and breeding methods for increasing resistance to brown root rot, Phoma slerotioides. This effort has resulted in an increase in brown root rot resistance in half-sib family lines compared to their parent variety. Progress is also being made toward the development of a standard protocol for evaluating alfalfa lines for resistance to brown root rot.
Ohio reported on a multi-state effort to evaluate performance of alfalfa varieties developed across six decades. Results suggest forage yield has increased over the past five decades, and that improvements in disease resistance are correlated with the higher yields and stand density as alfalfa stands age.
Objective 3. To Identify and Enhance Biological and Cultural Control Measures that Reduce Pest Populations and Improve Forage Alfalfa Persistence
Two states conducted research on biological and cultural control of insects in alfalfa during 2002. Virginia compared densities of natural enemies in treated and untreated glandular-haired and non-glandular-haired alfalfa at two sites. B. anurus represented 97% and 99% of the total parasitoids collected at the Piedmont and southwestern sites, respectively. Variety had no effect on rates of parasitization at either site nor did spray regime at the southwestern site despite reduced populations of AW larvae in treated plots. A sample date by spray regime interaction was found at the Piedmont site in 2002. However, the effect of spray regime on each sample date revealed no significant differences in rates of parasitization between spray regimes. Thus, glandular trichomes on 54H69 did not appear to impede overall biological control of AW larvae by Bathyplectes spp. females. Variety had no effect on rates of fungal infection by Z. phytonomi at the southwestern site. A sample date by variety interaction was significant for rates of fungal infection at the Piedmont site. However, the effect of variety on each sample date revealed no significant differences in rate of fungal infection between varieties.
Minnesota scientists evaluated two European parasitoid species released in Ontario during the late 1970‘s to control alfalfa blotch leafminer, Agromyza frontella. In 1999, both D. dryas and C. liriomyzae were parasitizing first-generation A. frontella in Ontario. The combined parasitism rate for both species as revealed by larval dissections was 97.5% by the end of the first A. frontella generation. Of the adult parasitoids reared, 86% were D. dryas and 14% were C. liriomyzae. By the end of the first A. frontella generation, 86% of parasitized hosts contained at least one unencapsulated parasitoid and could therefore produce an adult parasitoid, and 12% of parasitized hosts escaped parasitism by containing only encapsulated parasitoids. The sex ratio of D. dryas was even at emergence, but strongly female-biased in sweep samples from the field. Egg loads of D. dryas females were all greater than zero and as high in the field as our highest laboratory estimates, suggesting that egg availability does not limit fitness under the conditions that we observed in the field.
Objective 4. To Integrate Control Measures with Decision-Making Guidelines
for Adoption by Specific States/Regions
Two states provided reports on Objective 4. In Maryland, a web site, Potato Leafhopper as a Pest of Alfalfa, is being developed in conjunction with leafhopper specialists. The site focuses on identification, biology, and management of the insect. This effort is intended as a model for the development of other pest web sites as part of NC-226. In Michigan, patterns of potato leafhopper densities were determined within two alfalfa fields to test for optimum scouting protocols. They determined that intensive sampling is not economically feasible, thus decision-making is best conducted on a whole field basis instead of on a treatment zone basis.
Usefulness of Findings
The overall goal of the multistate project is to address a critical concern of farmers: the significant reduction in alfalfa stand life caused by pests and other factors. The lack of persistence significantly reduced profit associated with alfalfa, the principal forage component of a wide variety of agricultural production and conservation systems. In addition, the project plans to use the web site as a means to extend current information on the status of alfalfa pests and their management.
Work Planned for Next Year
Research will continue on each objective. Some of the original field studies are now focusing on the more critical final years during the lifespan of an alfalfa stand. An outline for a synthesis publication on integrating concepts of alfalfa persistence has been prepared, and work on this publication will continue during 2003. In addition, the website will be expanded to provide pest information beyond potato leafhopper.
Impacts
Publications
Publications:
Indiana
Justes, E., P. Thiebeau, J-C. Avice, G. Lemaire, J.J. Volenec, and A. Ourry. 2002. Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.). J. Exp. Bot. 53:111-121.
Volenec, J.J., S.M. Cunningham, D.M. Haagenson, W.K. Berg, B.C. Joern, and D.W. Wiersma. 2002. Physiological genetics of alfalfa improvement: past failures and future prospects. Field Crops Res. 75:97-110.
Haagenson D.M., S.M. Cunningham, B.C. Joern and J.J. Volenec. 2003. Autumn defoliation effects on alfalfa winter survival, root physiology, and gene expression. Crop Sci. (in press).
Cunningham S.M., P. Nadeau, Y. Castonguay, S. Leberge and J.J. Volenec. 2003. Raffinose and stachyose accumulation, galactinol synthase expression, and winter injury of contrasting Medicago sativa germplasms. Crop Sci. (in press).
Haagenson D.M., S.M. Cunningham and J.J. Volenec. 2003. Root physiology of less fall dormant, winter hardy alfalfa selections. Crop Sci. (in press).
Berg, W. K. , S. M. Cunningham, S. M. Brouder, B. C. Joern, KD Johnson and JJ Volenec. 2002. Phosphorus and potassium effects on alfalfa shoot regrowth and root physiology. American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. C02-cunningham133504-poster.
Berg, W. K. , S. M. Howard, S. M. Cunningham, S. M. Brouder, B.C. Joern, K.D. Johnson and J.J. Volenec. 2002. Phosphorus and potassium impact on alfalfa yield component responses and herbage nutrient concentrations. American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. S04-cunningham092229-poster.
Berg, W. K. , S. M. Cunningham, S. M. Howard, S. M. Brouder, B.C. Joern, K.D. Johnson and J.J. Volenec. 2002. How should you manage phosphorus and potassium fertility to enhance alfalfa yield and persistence? American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. A09-cunningham100644-oral.
Maryland
Fick, G.W., W.O. Lamp, and M. Collins. 2003. Integrated pest management in forages. In Forages: The Science of Grassland Agriculture, R.F. Barnes, D.A. Miller, and C.J. Nelson (eds.), 6th ed. Iowa State Univ. Press.
Michigan
None reported.
Minnesota
Heimpel, G.E. & F. Meloche. 2001. Biological control of alfalfa blotch leafminer (Diptera:
Agromyzidae) in Ontario: status and ecology of parasitoids 20 years after introduction
(Hymenoptera: Braconidae and Eulophidae). Great Lakes Entomologist 34: 17-26.
Ohio
Barta, A. L., R.M. Sulc, R. M., M.J. Ogle, and R.B. Hammond. 2002. Interaction between flooding or drought stress and potato leafhopper injury in alfalfa. Online. Plant Health Progress doi:10.1094/PHP-2002-0502-01-RS.
Barta, A.L., and R.M. Sulc. 2002. Interaction between waterlogging injury and irradiance level in alfalfa. Crop Sci. 42: 1529-1534.
Nutter, F.W. Jr., J. Guan, A.R. Gotlieb, L.H. Rhodes, C.R. Grau, and R.M. Sulc. 2002. Quantifying alfalfa yield losses caused by foliar diseases in Iowa, Ohio, Wisconsin, and Vermont. Plant Dis. 86:269-277.
Diedrick, K.A., R.M. Sulc, R.B. Hammond, and J.S. McCormick. 2002. Reduced insecticide rates and host plant resistance for controlling potato leafhopper in alfalfa. Agronomy Abstracts.
Diedrick, K.A., R.M. Sulc, R.B. Hammond, an A.L. Barta. 2002. Growth stage effects on alfalfa response to potato leafhopper injury. Agronomy Abstracts.
Barta,A.L., R.M. Sulc, and M.J. Ogle. 2002. Alfalfa plant loss in relation to time after establishment and environment. Agronomy Abstracts.
Lamb, J.F.S., C.C. Sheaffer, P.C. St. Amand, E.C. Brummer, L.H. Rhodes, M. Sulc, and D.J. Undersander. 2002. Comparing yield and forage quality of alfalfa cultivars released from the 1940‘s through the 1990‘s. In Proc. 38th North American Alfalfa Improvement Conf., Sacramento, CA, WI. 27-31 July 2002. Available online at http://www.naaic.org/Meetings/National/2002meeting/2002NAAICAbstracts.html
Ariss, J.J., L. H. Rhodes, R. M. Sulc, and R. B. Hammond. 2002. Effects of potato leafhopper injury and Fusarium crown rot on three alfalfa populations. In Proc. 38th North American Alfalfa Improvement Conf., Sacramento, CA, WI. 27-31 July 2002. Available online at http://www.naaic.org/Meetings/National/2002meeting/2002NAAICAbstracts.html
McCormick, J.S., R.M. Sulc, L.H. Rhodes, D.J. Barker, and R.B. Hammond. 2002. Ohio forage performance trials, 2002. Horticulture & Crop Science Series 195. Ohio State University. _ pp. Available at www.oardc.ohio-state.edu/forage2002.
South Dakota
None reported.
Wisconsin
None reported.
Wyoming
Gray, F. A., C. R. Hollingsworth and D. W. Koch. 2002. Biology and management of stand-decline diseases of irrigated alfalfa in the western U.S., pp 47-52. In, Proceedings of the Western Alfalfa & Forage Conference, 12-13 December. Reno, NV.
Larsen, R. C., C. R. Hollingsworth, G. J. Vandemark, M. A. Gritsenko and F. A. Gray. 2002. A rapid method using PCR-based SCAR markers for the detection and identification of Phoma sclerotioides, the cause of brown root rot disease of alfalfa. Plant Disease 86:928-932.
Gray, F. A. and G. D. Griffin. 2002. Plant parasitic nematodes of alfalfa in the United States. 2002. Proceedings of the 28th North American Alfalfa Improvement Conference (In Press).
Hollingsworth, C. R., F. A. Gray, D. W. Koch, R. W. Groose and T. E. Heald. 2002. Distribution and incidence of brown root rot (Phoma sclerotioides) of alfalfa in Wyoming U.S.A. Canadian Journal of Plant Pathology (accepted).
Gray, F. A., C. R. Hollingsworth and R. W. Groose. 2002. Brown root rot resistance, Phoma sclerotioides (G. Preuss ex Sacc.) In, Standard Tests to Characterize Alfalfa Cultivars. North American Alfalfa Improvement Conference publication. C. C. Fox, R. Berberet, F. A. Gray, C. R. Grau, D. L. Jessen and M. A. Peterson, eds. 1991, 3rd Edition. (accepted).
Virginia
Dellinger, T. A., R. R. Youngman, and C. A. Laub. 2003. Recovery of Oomyzus incertus (Hymenoptera: Eulophidae), a larval parasitoid of Hypera postica (Coleoptera: Curculionidae), in Virginia. J. Entomol. Sci. 38: 141-142.
Indiana
Justes, E., P. Thiebeau, J-C. Avice, G. Lemaire, J.J. Volenec, and A. Ourry. 2002. Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.). J. Exp. Bot. 53:111-121.
Volenec, J.J., S.M. Cunningham, D.M. Haagenson, W.K. Berg, B.C. Joern, and D.W. Wiersma. 2002. Physiological genetics of alfalfa improvement: past failures and future prospects. Field Crops Res. 75:97-110.
Haagenson D.M., S.M. Cunningham, B.C. Joern and J.J. Volenec. 2003. Autumn defoliation effects on alfalfa winter survival, root physiology, and gene expression. Crop Sci. (in press).
Cunningham S.M., P. Nadeau, Y. Castonguay, S. Leberge and J.J. Volenec. 2003. Raffinose and stachyose accumulation, galactinol synthase expression, and winter injury of contrasting Medicago sativa germplasms. Crop Sci. (in press).
Haagenson D.M., S.M. Cunningham and J.J. Volenec. 2003. Root physiology of less fall dormant, winter hardy alfalfa selections. Crop Sci. (in press).
Berg, W. K. , S. M. Cunningham, S. M. Brouder, B. C. Joern, KD Johnson and JJ Volenec. 2002. Phosphorus and potassium effects on alfalfa shoot regrowth and root physiology. American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. C02-cunningham133504-poster.
Berg, W. K. , S. M. Howard, S. M. Cunningham, S. M. Brouder, B.C. Joern, K.D. Johnson and J.J. Volenec. 2002. Phosphorus and potassium impact on alfalfa yield component responses and herbage nutrient concentrations. American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. S04-cunningham092229-poster.
Berg, W. K. , S. M. Cunningham, S. M. Howard, S. M. Brouder, B.C. Joern, K.D. Johnson and J.J. Volenec. 2002. How should you manage phosphorus and potassium fertility to enhance alfalfa yield and persistence? American Society of Agronomy Annual Meeting. Indianapolis, IN. Agron. Abstr. A09-cunningham100644-oral.
Maryland
Fick, G.W., W.O. Lamp, and M. Collins. 2003. Integrated pest management in forages. In Forages: The Science of Grassland Agriculture, R.F. Barnes, D.A. Miller, and C.J. Nelson (eds.), 6th ed. Iowa State Univ. Press.
Michigan
None reported.
Minnesota
Heimpel, G.E. & F. Meloche. 2001. Biological control of alfalfa blotch leafminer (Diptera:
Agromyzidae) in Ontario: status and ecology of parasitoids 20 years after introduction
(Hymenoptera: Braconidae and Eulophidae). Great Lakes Entomologist 34: 17-26.
Ohio
Barta, A. L., R.M. Sulc, R. M., M.J. Ogle, and R.B. Hammond. 2002. Interaction between flooding or drought stress and potato leafhopper injury in alfalfa. Online. Plant Health Progress doi:10.1094/PHP-2002-0502-01-RS.
Barta, A.L., and R.M. Sulc. 2002. Interaction between waterlogging injury and irradiance level in alfalfa. Crop Sci. 42: 1529-1534.
Nutter, F.W. Jr., J. Guan, A.R. Gotlieb, L.H. Rhodes, C.R. Grau, and R.M. Sulc. 2002. Quantifying alfalfa yield losses caused by foliar diseases in Iowa, Ohio, Wisconsin, and Vermont. Plant Dis. 86:269-277.
Diedrick, K.A., R.M. Sulc, R.B. Hammond, and J.S. McCormick. 2002. Reduced insecticide rates and host plant resistance for controlling potato leafhopper in alfalfa. Agronomy Abstracts.
Diedrick, K.A., R.M. Sulc, R.B. Hammond, an A.L. Barta. 2002. Growth stage effects on alfalfa response to potato leafhopper injury. Agronomy Abstracts.
Barta,A.L., R.M. Sulc, and M.J. Ogle. 2002. Alfalfa plant loss in relation to time after establishment and environment. Agronomy Abstracts.
Lamb, J.F.S., C.C. Sheaffer, P.C. St. Amand, E.C. Brummer, L.H. Rhodes, M. Sulc, and D.J. Undersander. 2002. Comparing yield and forage quality of alfalfa cultivars released from the 1940‘s through the 1990‘s. In Proc. 38th North American Alfalfa Improvement Conf., Sacramento, CA, WI. 27-31 July 2002. Available online at http://www.naaic.org/Meetings/National/2002meeting/2002NAAICAbstracts.html
Ariss, J.J., L. H. Rhodes, R. M. Sulc, and R. B. Hammond. 2002. Effects of potato leafhopper injury and Fusarium crown rot on three alfalfa populations. In Proc. 38th North American Alfalfa Improvement Conf., Sacramento, CA, WI. 27-31 July 2002. Available online at http://www.naaic.org/Meetings/National/2002meeting/2002NAAICAbstracts.html
McCormick, J.S., R.M. Sulc, L.H. Rhodes, D.J. Barker, and R.B. Hammond. 2002. Ohio forage performance trials, 2002. Horticulture & Crop Science Series 195. Ohio State University. _ pp. Available at www.oardc.ohio-state.edu/forage2002.
South Dakota
None reported.
Wisconsin
None reported.
Wyoming
Gray, F. A., C. R. Hollingsworth and D. W. Koch. 2002. Biology and management of stand-decline diseases of irrigated alfalfa in the western U.S., pp 47-52. In, Proceedings of the Western Alfalfa & Forage Conference, 12-13 December. Reno, NV.
Larsen, R. C., C. R. Hollingsworth, G. J. Vandemark, M. A. Gritsenko and F. A. Gray. 2002. A rapid method using PCR-based SCAR markers for the detection and identification of Phoma sclerotioides, the cause of brown root rot disease of alfalfa. Plant Disease 86:928-932.
Gray, F. A. and G. D. Griffin. 2002. Plant parasitic nematodes of alfalfa in the United States. 2002. Proceedings of the 28th North American Alfalfa Improvement Conference (In Press).
Hollingsworth, C. R., F. A. Gray, D. W. Koch, R. W. Groose and T. E. Heald. 2002. Distribution and incidence of brown root rot (Phoma sclerotioides) of alfalfa in Wyoming U.S.A. Canadian Journal of Plant Pathology (accepted).
Gray, F. A., C. R. Hollingsworth and R. W. Groose. 2002. Brown root rot resistance, Phoma sclerotioides (G. Preuss ex Sacc.) In, Standard Tests to Characterize Alfalfa Cultivars. North American Alfalfa Improvement Conference publication. C. C. Fox, R. Berberet, F. A. Gray, C. R. Grau, D. L. Jessen and M. A. Peterson, eds. 1991, 3rd Edition. (accepted).
Virginia
Dellinger, T. A., R. R. Youngman, and C. A. Laub. 2003. Recovery of Oomyzus incertus (Hymenoptera: Eulophidae), a larval parasitoid of Hypera postica (Coleoptera: Curculionidae), in Virginia. J. Entomol. Sci. 38: 141-142.