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: 10/01/2000 to 09/01/2001
- Date of Report: 05/03/2002
- Annual Meeting Dates: 02/26/2002 to 02/27/2002
Participants
[Minutes]
Accomplishments
Objective 1. To Elucidate Mechanisms By Which Biotic Agents Interact With Abiotic Factors to Limit Stand Persistence of Forage Alfalfa
Reports were received from three states for Objective 1. In Indiana, the persistence of alfalfa plants in response to varying levels of phosphorus and potassium was studied. Forage yield components have been measured during the 5 year study. The number of shoots per plant did not differ among the treatments, however, mass per shoot increased as phosphorus and potassium fertility improved. While potassium fertility did not affect plant persistence, increased phosphorus fertility reduced plant density. These plots will be re-sampled during 2002. In Michigan, patterns of soil properties of 5 production fields were related to patterns of potato leafhopper densities and alfalfa yield. Most correlations found during the first year of the study did not continue into the second year, however, alfalfa weevil and potato leafhopper were negatively correlated to plant height. Soils with higher organic matter are able to hold more moisture, which leads to taller plants, and greater insect pressure leads to stunted plants. In Ohio, a controlled environment study demonstrated the importance of potato leafhopper injury on root growth and TNC accumulation. In addition, Ohio reported on a field persistence study in which plant loss was greater at two spring-seeded sites compared to a fall-seeded site. Plants and soil were sampled to related plant mortality to root pathogens.
Objective 2. To Enhance Alfalfa Persistence Through Improved Plant Resistance to Key Pests by Conventional Breeding and Genetic Engineering Approaches
Six states reported studies under Objective 2. Four states reported on studies examining performance of potato leafhopper (PLH) resistant alfalfa cultivars, including Maryland, Michigan, Ohio, Minnesota, and Virginia. In field studies where yields were reported, resistant cultivars usually had higher forage yield than check cultivars when PLH populations were high and insecticide was not applied, but insecticide treatment usually increased yield of all varieties (only Virginia reported there were no significant differences in seasonal yield). In the seeding year, Ohio reported a significant reduction in PLH population growth in field plots of a resistant cultivar as compared with a susceptible cultivar, and insecticide treatment in the highly resistant cultivar was not economically justified in any of the three harvests but was justified in all three harvests of the susceptible cultivar. Maryland reported that equivalent exposure to PLH resulted in less impact on photosynthesis in resistant cultivars or clones as compared with susceptible cultivars or clones, suggesting that resistant germplasm exhibit tolerance to PLH. Michigan reported that during peak PLH density crude protein, maturity, and yields were greater in the resistant cultivars compared to the susceptible cultivars. The Ohio and Maryland data suggests the need for an adjustment in the economic action thresholds for resistant cultivars, based on lower PLH population growth rate and the tolerance mechanism.
Maryland reported the presence of glandular-hairs in PLH-resistant cultivars does not appear to negatively affect the density of other sap feeders; the assemblages of other sap feeders appear largely random. Ohio and Virginia reported on infestations of alfalfa weevil in their studies evaluating PLH-resistant cultivars. The PLH-resistant cultivars showed no reduction in alfalfa weevil densities compared with standard cultivars, and in fact, Virginia noted an increase in alfalfa weevil density in one PLH-resistant cultivar at two locations. Ohio concluded that PLH-resistant cultivars showed no resistance to alfalfa weevil and alfalfa weevil damage.
Three states reported on plant pathogen studies under Objective 2. Kentucky is conducting field screenings for Sclerotinia crown and stem rot and allowing private companies to make selections of surviving plants for their breeding programs. Ohio completed a greenhouse study investigating the interaction between PLH and Fusarium crown rot in alfalfa. The lack of any significant Fusarium x PLH x population interaction indicated that the nature of the effects of Fusarium were additive. Wyoming reported a survey of brown root rot (BRR) presence in alfalfa, a pathogenicity study of fungal isolates of BRR, and that progress is being made in breeding for BRR resistance in alfalfa.
Objective 3. To Identify and Enhance Biological and Cultural Control Measures that Reduce Pest Populations and Improve Forage Alfalfa Persistence
Three states reported any work in 2001 on biological and cultural control measures of pest populations. Both Illinois and Minnesota worked with alfalfa blotch leafminers (ABLM). In Illinois, ABLM was detected in 14 of 20 counties sampled north of Interstate Highway 80 in early May. Highest incidence found approximately one fly per sweep and 95% of stems displaying pinhole feeding. However, there were never more than 25% damaged trifoliolate leaves on a single stem. Samples collected in July displayed much lower adult populations, with only 4 of 68 counties having adults present and populations never exceeded 0.2 flys per sweep. A degree-day model has been developed and independently validated for ABLM; the phenological stage that ABLM populations were in during the two sampling periods will be determined retrospectively. In addition, parasitoids were collected from the sweep samples to determine whether biological control agents may have accompanied the invasion of ABLM in Illinois. No Dacnusa dryas have been found, and efforts to identify potential Chrysocharis liriomyzae are underway. In Minnesota, D. dryas has been released and has become established while C. liriomyzae has become established on its own. ABLM densities were so low in Minnesota in 2001 that surveys were not attempted. Virginia continues to compare densities of natural enemies of alfalfa weevil in treated and untreated glandular-haired and non-glandular-haired alfalfa at two locations. Bathyplectes anurus was the predominant parasitoid found at both locations, representing 81% and 91% of the total parasitoids reared from AW larvae at the Piedmont and southwestern sites, respectively. No differences in rates of parasitization or of fungal infection due to variety were found at either location. Glandular-hairs did not appear to impede overall parasitization of AW larvae by Bathyplectes spp. females.
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.
Reports were received from three states for Objective 1. In Indiana, the persistence of alfalfa plants in response to varying levels of phosphorus and potassium was studied. Forage yield components have been measured during the 5 year study. The number of shoots per plant did not differ among the treatments, however, mass per shoot increased as phosphorus and potassium fertility improved. While potassium fertility did not affect plant persistence, increased phosphorus fertility reduced plant density. These plots will be re-sampled during 2002. In Michigan, patterns of soil properties of 5 production fields were related to patterns of potato leafhopper densities and alfalfa yield. Most correlations found during the first year of the study did not continue into the second year, however, alfalfa weevil and potato leafhopper were negatively correlated to plant height. Soils with higher organic matter are able to hold more moisture, which leads to taller plants, and greater insect pressure leads to stunted plants. In Ohio, a controlled environment study demonstrated the importance of potato leafhopper injury on root growth and TNC accumulation. In addition, Ohio reported on a field persistence study in which plant loss was greater at two spring-seeded sites compared to a fall-seeded site. Plants and soil were sampled to related plant mortality to root pathogens.
Objective 2. To Enhance Alfalfa Persistence Through Improved Plant Resistance to Key Pests by Conventional Breeding and Genetic Engineering Approaches
Six states reported studies under Objective 2. Four states reported on studies examining performance of potato leafhopper (PLH) resistant alfalfa cultivars, including Maryland, Michigan, Ohio, Minnesota, and Virginia. In field studies where yields were reported, resistant cultivars usually had higher forage yield than check cultivars when PLH populations were high and insecticide was not applied, but insecticide treatment usually increased yield of all varieties (only Virginia reported there were no significant differences in seasonal yield). In the seeding year, Ohio reported a significant reduction in PLH population growth in field plots of a resistant cultivar as compared with a susceptible cultivar, and insecticide treatment in the highly resistant cultivar was not economically justified in any of the three harvests but was justified in all three harvests of the susceptible cultivar. Maryland reported that equivalent exposure to PLH resulted in less impact on photosynthesis in resistant cultivars or clones as compared with susceptible cultivars or clones, suggesting that resistant germplasm exhibit tolerance to PLH. Michigan reported that during peak PLH density crude protein, maturity, and yields were greater in the resistant cultivars compared to the susceptible cultivars. The Ohio and Maryland data suggests the need for an adjustment in the economic action thresholds for resistant cultivars, based on lower PLH population growth rate and the tolerance mechanism.
Maryland reported the presence of glandular-hairs in PLH-resistant cultivars does not appear to negatively affect the density of other sap feeders; the assemblages of other sap feeders appear largely random. Ohio and Virginia reported on infestations of alfalfa weevil in their studies evaluating PLH-resistant cultivars. The PLH-resistant cultivars showed no reduction in alfalfa weevil densities compared with standard cultivars, and in fact, Virginia noted an increase in alfalfa weevil density in one PLH-resistant cultivar at two locations. Ohio concluded that PLH-resistant cultivars showed no resistance to alfalfa weevil and alfalfa weevil damage.
Three states reported on plant pathogen studies under Objective 2. Kentucky is conducting field screenings for Sclerotinia crown and stem rot and allowing private companies to make selections of surviving plants for their breeding programs. Ohio completed a greenhouse study investigating the interaction between PLH and Fusarium crown rot in alfalfa. The lack of any significant Fusarium x PLH x population interaction indicated that the nature of the effects of Fusarium were additive. Wyoming reported a survey of brown root rot (BRR) presence in alfalfa, a pathogenicity study of fungal isolates of BRR, and that progress is being made in breeding for BRR resistance in alfalfa.
Objective 3. To Identify and Enhance Biological and Cultural Control Measures that Reduce Pest Populations and Improve Forage Alfalfa Persistence
Three states reported any work in 2001 on biological and cultural control measures of pest populations. Both Illinois and Minnesota worked with alfalfa blotch leafminers (ABLM). In Illinois, ABLM was detected in 14 of 20 counties sampled north of Interstate Highway 80 in early May. Highest incidence found approximately one fly per sweep and 95% of stems displaying pinhole feeding. However, there were never more than 25% damaged trifoliolate leaves on a single stem. Samples collected in July displayed much lower adult populations, with only 4 of 68 counties having adults present and populations never exceeded 0.2 flys per sweep. A degree-day model has been developed and independently validated for ABLM; the phenological stage that ABLM populations were in during the two sampling periods will be determined retrospectively. In addition, parasitoids were collected from the sweep samples to determine whether biological control agents may have accompanied the invasion of ABLM in Illinois. No Dacnusa dryas have been found, and efforts to identify potential Chrysocharis liriomyzae are underway. In Minnesota, D. dryas has been released and has become established while C. liriomyzae has become established on its own. ABLM densities were so low in Minnesota in 2001 that surveys were not attempted. Virginia continues to compare densities of natural enemies of alfalfa weevil in treated and untreated glandular-haired and non-glandular-haired alfalfa at two locations. Bathyplectes anurus was the predominant parasitoid found at both locations, representing 81% and 91% of the total parasitoids reared from AW larvae at the Piedmont and southwestern sites, respectively. No differences in rates of parasitization or of fungal infection due to variety were found at either location. Glandular-hairs did not appear to impede overall parasitization of AW larvae by Bathyplectes spp. females.
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.
Impacts
- 1.To elucidate mechanisms by which biotic agents interact with abiotic factors to limit stand persistence of forage alfalfa
- 2.To enhance alfalfa persistence through improved plant resistance to key pests by conventional breeding and genetic engineering approaches
- 3.To identify and enhance biological and cultural control measures that reduce pest populations and improve forage alfalfa persistence
- 4.To integrate control measures with decision-making guidelines for adoption by specific states/regions.
Publications
Publications:
Indiana
Noquet, C., J.C. Avice, A. Ourry, J.J. Volenec, S.M. Cunningham and J. Boucaud. 2001. Effects of environmental factors and endogenous signals on N uptake, N partitioning and taproot vegetative storage protein accumulation in Medicago sativa. Aust. J. Plant Physiol. 28:279-288.
Cunningham, S.M., J.A. Gana, J.J. Volenec, and L.R. Teuber. 2001. Winter hardiness, root physiology, and gene expression in successive fall dormancy selections from ‘Mesilla‘ and ‘CUF 101‘ alfalfa. Crop Sci. 41:1091-1098.
Shibli, R.A., D.M. Haagenson, S.M. Cunningham, W.K. Berg, and J.J. Volenec. 2001. Cryopreservation of alfalfa (Medicago sativa L.) cells by encapsulation-dehydration. Plant Cell Rpt. 20:445-450.
Ourry, A., J.H. McDuff, J.J. Volenec, and J.P. Gaudillere. 2001. Nitrogen traffic during plant growth and development. p. 255-273. In P.J. Lea and J.F. Morot-Gaudry (eds.), Plant Nitrogen. Springer-Verlag, Berlin.
Noquet, C., J.C. Avice, A. Ourry, J.J. Volenec, and J. Boucaud. 2001. Effects of photoperiod, low temperature, and N nutrition on VSP accumulation in taproots of alfalfa. Proc. Int. Grassl. Congress (in press).
Gana, J.A., S.M. Cunningham, and J.J. Volenec. 2001. Allele-specific expression of a cold acclimation-responsive gene family in alfalfa buds and taproots. Abstr. #726. Amer. Soc. Plant Biol. Annual Meeting. http://www.rycomusa.com/aspp2001/public/P45/0694.html
Haagenson, D.M., S.M. Cunningham, and J.J. Volenec. 2001. Water relations and dehydrin gene expression in roots of contrasting alfalfa cultivars during cold acclimation. Abstr. #387. Amer. Soc. Plant Biol. Annual Meeting. http://www.rycomusa.com/aspp2001/public/P33/0690.html.
Berg, W. K., S.M. Cunningham, B.C. Joern, K.D. Johnson, and J.J. Volenec. 2001. Relationship of soil and tissue P and K concentrations on and alfalfa yield and persistence. Agron. Abstr. (CD-ROM) TSNo. s04-cunningham152819P.
Berg W.K., S.M. Cunningham, B.C. Joern, K.D. Johnson, and J.J. Volenec. 2001. P and K effects on root physiology and persistence of field-grown alfalfa. Agron. Abstr. (CD-ROM) TSNo. c02-volenec153842-P.
Maryland
Fick, G.W., W.O. Lamp, and M. Collins. 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. (In press)
Lamp, W.O., G.R. Nielsen, B. Quebedeaux, and Z. Wang. 2001. Potato leafhopper (Homoptera: Cicadellidae) injury disrupts basal transport of 14C-labelled photoassimilates in alfalfa. Journal of Economic Entomology 94: 93-97.
Michigan
Leep, R.H., J. R. Andresen and P. Jeranyama. 2001."Fall Dormancy and Snow Depth Effects on Winterkill of Alfalfa." Agron. J. 93, Pgs. 1142-1148. ASA, Madison, WI.
Leep, R.H., Dietz, T. and Doo-Hong Min. 2001. Perennial Legume and Grass Forage Variety Selection in Michigan. Michigan State University. Available at http://www.msue.msu.edu/fis/extension_documents/extpub01.pdf
Minnesota
Heimpel, G.E. and 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 (in press).
Sheaffer, C.C., N.P. Martin, J.G. Jewett, J. Halgerson, R.D. Moon, and G.R. Cuomo. 2000. Sampling requirements for forage quality characterization of rectangular hay bales. Agron. Journal. 92:64-68.
Pennsylvania
None reported
Ohio
Venkatesh, R., R.M. Sulc, S.K. Harrison, J.D. Metzger, K.A. Diedrick, and R.B. Hammond. 2001. Volatile compounds from alfalfa clones differing in potato leafhopper resistance. Agronomy Abstracts.
Barta, A.L., R.M. Sulc, M.J. Ogle, and R.B. Hammond. 2001. Abiotic stress effects on potato leafhopper injury in alfalfa. Agronomy Abstracts.
Sulc, R.M., E.V. Santen, K.D. Johnson, C.C. Sheaffer, D.J. Undersander, L.W. Bledsoe, D.B. Hogg, and H.R. Willson. 2001. Glandular-haired cultivars reduce potato leafhopper damage in alfalfa. Agron. J. 93:1287-1296.
Sulc, R.M., J.S. McCormick, L.H. Rhodes, D.J. Barker, and R.B. Hammond. 2001. Ohio forage performance trials. Horticulture & Crop Science Series 195. Ohio State University. Available at http://www.ag.ohio-state.edu/~perf/.
Cox, J. J. 2001. Effects of potato leafhopper injury and Fusarium crown rot on three alfalfa populations. M. S. Thesis, The Ohio State University, Columbus. 119 pp.
South Dakota
None reported
Wisconsin
None reported
Wyoming
Hollingsworth, C.R., F.A. Gray, R.W. Groose and C.W. Mims. 2001. Morphological responses of Canadian and U.S.A. isolates of Phoma sclerotioides to different growth media, temperatures and light. MYCOTAXON 81:331-339 (In Press)
Gray, F.A., C.R. Hollingsworth and D.W. Koch. 2001. Occurrence of brown root rot of alfalfa in the continental United States. Joint Meeting of the Canadian Phytopathological Society and the Pacific Division of the American Phytopathological Society. June 18-21, 2000. Victoria, B.C. Phytopathology 91, No. 6 (Supplement) S184.
Hollingsworth, C.R., F.A. Gray, R.W. Groose, D.W. Koch and T.E. Heald. 2001. Development of a protocol for identifying alfalfa, Medicago sativa ssp. sativa reaction to infection by Phoma sclerotioides causal organism of brown root rot. Phytopathology 91, No. 6 (Supplement) S39.
Larsen, R.C., G.J. Vandemark, M.A. Gritsenko, C.R. Hollingsworth, and F.A. Gray. 2001. PCR-based SCAR markers for the detection and identification of Phoma sclerotioides - the cause of brown root rot disease of alfalfa. Phytopathology 91, No. 6 (Supplement) S53.
Larsen, R.C., G.J. Vandemark, F.A. Gray and M. Gritsenko. 2001. PCR-based markers for the identification of Phoma sclerotioides infecting alfalfa. Phytopathology 91, Vol. 6 (Supplement) S186.
Gray, F.A., C.R. Hollingsworth, D.W. Koch and R.W. Groose. 2001. A preliminary test for characterizing alfalfa cultivars for brown root rot resistance. Presented at the Joint Western Society of Crop Science/Western Alfalfa Improvement Conference Meeting, Tucson, AZ, June 11-13, 2001.
Virginia
Kuhar, T. P., R. R. Youngman, and C. A. Laub. 2001. Alfalfa weevil (Coleoptera: Curculionidae) phenology with its host crop and parasitoids in Virginia. J. Entomol. Sci. 36: 352-365.
Indiana
Noquet, C., J.C. Avice, A. Ourry, J.J. Volenec, S.M. Cunningham and J. Boucaud. 2001. Effects of environmental factors and endogenous signals on N uptake, N partitioning and taproot vegetative storage protein accumulation in Medicago sativa. Aust. J. Plant Physiol. 28:279-288.
Cunningham, S.M., J.A. Gana, J.J. Volenec, and L.R. Teuber. 2001. Winter hardiness, root physiology, and gene expression in successive fall dormancy selections from ‘Mesilla‘ and ‘CUF 101‘ alfalfa. Crop Sci. 41:1091-1098.
Shibli, R.A., D.M. Haagenson, S.M. Cunningham, W.K. Berg, and J.J. Volenec. 2001. Cryopreservation of alfalfa (Medicago sativa L.) cells by encapsulation-dehydration. Plant Cell Rpt. 20:445-450.
Ourry, A., J.H. McDuff, J.J. Volenec, and J.P. Gaudillere. 2001. Nitrogen traffic during plant growth and development. p. 255-273. In P.J. Lea and J.F. Morot-Gaudry (eds.), Plant Nitrogen. Springer-Verlag, Berlin.
Noquet, C., J.C. Avice, A. Ourry, J.J. Volenec, and J. Boucaud. 2001. Effects of photoperiod, low temperature, and N nutrition on VSP accumulation in taproots of alfalfa. Proc. Int. Grassl. Congress (in press).
Gana, J.A., S.M. Cunningham, and J.J. Volenec. 2001. Allele-specific expression of a cold acclimation-responsive gene family in alfalfa buds and taproots. Abstr. #726. Amer. Soc. Plant Biol. Annual Meeting. http://www.rycomusa.com/aspp2001/public/P45/0694.html
Haagenson, D.M., S.M. Cunningham, and J.J. Volenec. 2001. Water relations and dehydrin gene expression in roots of contrasting alfalfa cultivars during cold acclimation. Abstr. #387. Amer. Soc. Plant Biol. Annual Meeting. http://www.rycomusa.com/aspp2001/public/P33/0690.html.
Berg, W. K., S.M. Cunningham, B.C. Joern, K.D. Johnson, and J.J. Volenec. 2001. Relationship of soil and tissue P and K concentrations on and alfalfa yield and persistence. Agron. Abstr. (CD-ROM) TSNo. s04-cunningham152819P.
Berg W.K., S.M. Cunningham, B.C. Joern, K.D. Johnson, and J.J. Volenec. 2001. P and K effects on root physiology and persistence of field-grown alfalfa. Agron. Abstr. (CD-ROM) TSNo. c02-volenec153842-P.
Maryland
Fick, G.W., W.O. Lamp, and M. Collins. 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. (In press)
Lamp, W.O., G.R. Nielsen, B. Quebedeaux, and Z. Wang. 2001. Potato leafhopper (Homoptera: Cicadellidae) injury disrupts basal transport of 14C-labelled photoassimilates in alfalfa. Journal of Economic Entomology 94: 93-97.
Michigan
Leep, R.H., J. R. Andresen and P. Jeranyama. 2001."Fall Dormancy and Snow Depth Effects on Winterkill of Alfalfa." Agron. J. 93, Pgs. 1142-1148. ASA, Madison, WI.
Leep, R.H., Dietz, T. and Doo-Hong Min. 2001. Perennial Legume and Grass Forage Variety Selection in Michigan. Michigan State University. Available at http://www.msue.msu.edu/fis/extension_documents/extpub01.pdf
Minnesota
Heimpel, G.E. and 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 (in press).
Sheaffer, C.C., N.P. Martin, J.G. Jewett, J. Halgerson, R.D. Moon, and G.R. Cuomo. 2000. Sampling requirements for forage quality characterization of rectangular hay bales. Agron. Journal. 92:64-68.
Pennsylvania
None reported
Ohio
Venkatesh, R., R.M. Sulc, S.K. Harrison, J.D. Metzger, K.A. Diedrick, and R.B. Hammond. 2001. Volatile compounds from alfalfa clones differing in potato leafhopper resistance. Agronomy Abstracts.
Barta, A.L., R.M. Sulc, M.J. Ogle, and R.B. Hammond. 2001. Abiotic stress effects on potato leafhopper injury in alfalfa. Agronomy Abstracts.
Sulc, R.M., E.V. Santen, K.D. Johnson, C.C. Sheaffer, D.J. Undersander, L.W. Bledsoe, D.B. Hogg, and H.R. Willson. 2001. Glandular-haired cultivars reduce potato leafhopper damage in alfalfa. Agron. J. 93:1287-1296.
Sulc, R.M., J.S. McCormick, L.H. Rhodes, D.J. Barker, and R.B. Hammond. 2001. Ohio forage performance trials. Horticulture & Crop Science Series 195. Ohio State University. Available at http://www.ag.ohio-state.edu/~perf/.
Cox, J. J. 2001. Effects of potato leafhopper injury and Fusarium crown rot on three alfalfa populations. M. S. Thesis, The Ohio State University, Columbus. 119 pp.
South Dakota
None reported
Wisconsin
None reported
Wyoming
Hollingsworth, C.R., F.A. Gray, R.W. Groose and C.W. Mims. 2001. Morphological responses of Canadian and U.S.A. isolates of Phoma sclerotioides to different growth media, temperatures and light. MYCOTAXON 81:331-339 (In Press)
Gray, F.A., C.R. Hollingsworth and D.W. Koch. 2001. Occurrence of brown root rot of alfalfa in the continental United States. Joint Meeting of the Canadian Phytopathological Society and the Pacific Division of the American Phytopathological Society. June 18-21, 2000. Victoria, B.C. Phytopathology 91, No. 6 (Supplement) S184.
Hollingsworth, C.R., F.A. Gray, R.W. Groose, D.W. Koch and T.E. Heald. 2001. Development of a protocol for identifying alfalfa, Medicago sativa ssp. sativa reaction to infection by Phoma sclerotioides causal organism of brown root rot. Phytopathology 91, No. 6 (Supplement) S39.
Larsen, R.C., G.J. Vandemark, M.A. Gritsenko, C.R. Hollingsworth, and F.A. Gray. 2001. PCR-based SCAR markers for the detection and identification of Phoma sclerotioides - the cause of brown root rot disease of alfalfa. Phytopathology 91, No. 6 (Supplement) S53.
Larsen, R.C., G.J. Vandemark, F.A. Gray and M. Gritsenko. 2001. PCR-based markers for the identification of Phoma sclerotioides infecting alfalfa. Phytopathology 91, Vol. 6 (Supplement) S186.
Gray, F.A., C.R. Hollingsworth, D.W. Koch and R.W. Groose. 2001. A preliminary test for characterizing alfalfa cultivars for brown root rot resistance. Presented at the Joint Western Society of Crop Science/Western Alfalfa Improvement Conference Meeting, Tucson, AZ, June 11-13, 2001.
Virginia
Kuhar, T. P., R. R. Youngman, and C. A. Laub. 2001. Alfalfa weevil (Coleoptera: Curculionidae) phenology with its host crop and parasitoids in Virginia. J. Entomol. Sci. 36: 352-365.