Brief Summary of Minutes of Annual Meeting

The annual meeting was held at the University of Wyoming in Laramie. It was suggested we contact Byron Adams, BYU, and Patricia Stock for U of Arizona in Tucson to join the group. Officers for 2004 are; Chair: Ed Caswell-Chen, Vice-Chair: Pat Donald, Secretary: Brent Sipes. The next meeting will be held in Boise, Idaho on November 5 and 6, 2004 and will be hosted by Saad Hafez. October 3, 2003 started the beginning of our new 5-year project with the same title but with a different number (W-1186) and one additional objective.

Objective 1. Characterize genetic variability as related to PPN responses to resistance, environment, biological processes, and morphology. Studies conducted in California using phylogenetic analyses of root-knot nematodes based on patterns of nucleotide substitutions identified a 3-bp insertion within the interior of the rDNA D3 region. This provides support for a division between the automictic species Meloidogyne hapla and the apomictic species M. aerenaria, M. incognita and M. javanica. These results should aid in clarifying the taxonomic and evolutionary relationships between these closely related species. Analysis of evolutionary forces influencing pathogen and nematode evolution in plant agricultural ecosystems was made for nematode-crop associations from California and other states and countries. In comparisons of migration, reproduction system, and population size, migration was found to be the most important factor driving evolution as measured by the rate of virulence development in nematodes following introduction of resistant crop varieties and rootstocks. Isolates of M. konaensis from Hawaii, found to contain at least four esterase phenotypes, did not differ morphologically but did differ in parasitic ability on coffee. These studies will aid in the eventual control of this root parasite on the big island of Hawaii. In Nebraska, bar codes (partial 18S rDNA sequences) were developed for plant parasitic nematodes. Databases of mitochondrial and ITS1 sequences are also being constructed for Meloidogyne and other PPN species. Studies in Michigan have found soil population of biological antagonists to be associated with low populations of M. hapla. These studies will determine the overall impact of pesticides on these nematode antagonists. In Tennessee, soil temperatures in pot cultures were affected by the temperature of water applied during the winter months. This in turn effected soil populations of H. glycines in soybean standard check cultivars during their 18-month incubation period. Also, there was an interaction between the nematode populations and soybean check lines for reproductive rates of H. glycines. Objective 2. Determine nematode fitness and adaptability relative to environment, host plant, and host resistance. Studies conducted in Tennessee showed that fecundity of ten selected populations of H. glycines varied on both resistant and susceptible cultivars of soybeans. In studies conducted in Idaho, egg hatch of M. chitwoodi was progressively reduced with the application of plant extracts of rape and mustard cultivars. Studies conducted in New Mexico found egg production and number of reproductive females of M. incognita per unit of root mass, along with individual nematode fecundity, to be greater on chile pepper than on either yellow or purple nutsedge. When egg inoculum from different hosts was compared, inoculum from chile resulted in greater egg production and number of reproductive females per unit of chile root mass than did similar amounts of inoculum from either nutsedge species. In Michigan studies, the fungal antagonist, Hirsutella minnesontesis, displayed ecological fitness to populations of M. hapla from five different states indicating its potential as a bio-control agent over a wide geographical area. In California, studies on the bagging phenomenon during the Caenorhaditis elegans life-cycle may shed light on survival strategies of plant parasitic nematodes. Objective 3. Design and develop management strategies for cyst and root-knot nematodes relative to genetic variability. Tests conducted in Idaho found several Plant Introduction accessions to have tolerance to the sugar beet cyst nematode, Heterodera schachtii. Also, two cultivars of soybean were found to display tolerance to M. chitwoodi in greenhouse screening trials. It was also found that fall plantings of oil radish and mustard cultivars reduced soil populations of M. chitwoodi and increased subsequent potato yields and marketable tubers. Molecular bar coding is being developed in Nebraska for use in resolving quarantine issues with U.S. potato shipments leaving the country. Efforts are being made in Washington State to incorporate organic nematicides and green manures in combination with half the recommended rate of synthetic nematicides towards controlling M. chitwoodi. Efforts are being made in Michigan to incorporate soil properties into a site-specific management model for plant parasitic nematodes. Field tests in Wyoming confirmed the suspected resistance of an experimental sugar beet variety of Syngenta, to the sugar beet cyst nematode, H. schachtii. Yields were similar to a standard check variety grown in the area. Rhizosphere soil populations of H. schachtii were reduced more in the resistant than in the susceptible cultivar. In another study with sugar beets in Wyoming, where soil population ranged from 2.0 to 23.0 eggs and J2/cc soil, GPS site-specific technology for variable rate, pre-plant application of Telone II, provided extra profit ranging from $4.00 per acre in heavily infested sites to $69.00 per acre in lightly infested sites. In New Mexico, a 3-year rotation with M. incognita - resistant alfalfa provided better control of both nutsedge and the southern root-knot nematode in chile pepper than the standard soil fumigation treatments with 1,3-D. In Oregon, Telone II soil fumigant was effective in suppressing soil populations of the Columbia root-knot nematode but not Verticillium wilt, while the reverse was true with Metam sodium. Results indicate that both fumigants may be necessary in fields where both potato pathogens occur.

Avendano, F., O. Schbenberger, F.J. Pierce and Melakeberhan. 2003. Geostatistical analysis of field spatial distribution patterns of the soybean cyst nematode, Heterodera glycines. Agronomy Journal, 93: 936-948. Bosland, P.W., Y. Zewdie, and S.H. Thomas. 2003. NuMex Nematador, southern root-knot resistant cayenne pepper. HortScience 38:631-632. Chen, J., and E.P. Caswell-Chen. 2003. The ecology of C. elegans: Phenotypic plasticity, survival, and facultative vivipary. Journal of Nematology. 35:329-330 (Abstr.). Chen, J., and E.P. Caswell-Chen. 2003. Bagging as a part of the C. elegans life cycle. Program and Abstracts of 14th International C. elegans meeting. pg. 192 (Abstr.). Chen, P. and P.A. Roberts. 2003. Virulence in Meloidogyne hapla differentiated by resistance in common bean (Phaseolus vulgaris). Nematology 5:39-47. Fiore, C., L.W. Murray, I. Ray, J. Schroeder and S.H. Thomas. 2003. Chile response to rotational crops for nutsedge and nematode suppression. Proceedings, Western Society of Weed Science 56:60. Gray, F.A., D.W. Koch, H.J. Smith, L.J. Held and J.M. Krall. 2003. Controlling the sugar beet nematode (Heterodera schachtii) in the U.S. A., p. 251, Proceedings of the 2003 International Congress of Plant Pathology, Christchurch, New Zealand, Feb. 2-7. Greenfield, B.J., J. Schroeder, S.H. Thomas, and L.W. Murray. 2003. Root-knot nematodes and tuber size affect early season growth of purple and yellow nutsedges. Proceedings, Western Society of Weed Science 56:92. Hafez, S.L. and P. Sundararaj. 2001. Chemical nematicides for the suppression of Meloidogyne chitwoodi and M. hapla on potato. International Journal of Nematology. 11: 192 - 194. Hafez, S.L. and P. Sundararaj. 2001. Impact of nematode management options on the yield and nutrition status of potato, solanum tuberosum. International Journal of Nematology. 11: 195  1999. Hafez, S.L. and P. Sundararaj. 2001. Nonchemical alternatives for sugarbeet cyst nematode management in Idaho. Proceedings of Annual International Conference on Methyl bromide alternatives and emission reductions held on Novemebr 5-9, 2001 at San Diego, California. 86-1 to 86-4. Hafez, S. L. and P. Sundararaj. 2002. Chemical options for the management of Heterodera schachtii on sugar beet under field conditions. Nematology. 4:1, 295. Hafez, S.L. and P. Sundararaj. 2002. Chemical options for the management of stubby root nematodes on potato. International Journal of Nematology. 12: 73 - 75. Hafez, S. L. and P. Sundararaj. 2002. Comparative efficacy of fosthiazate formulations for the management of Meloidogyne chitwoodi in Idaho potatoes. Nematology. 4:1, 296. Hafez, S.L. and P. Sundararaj. 2002. Efficacy of chemical nematicides for the management of Meloidogyne chitwoodi on potato. International Journal of Nematology. 12: 76 - 78. Hafez, S. L. and P. Sundararaj. 2002. Evaluation of nematicides for the management of Meloidogyne chitwoodi on potato in Idaho. Nematology. 4:1, 295-296. Hafez, S.L. and P. Sundararaj. 2002. Integrated nematode management options for the sustainable potato production. Proceedings of the University of Idaho Winter Commodity Schools  2002. 111-116. Hafez, S.L. and P. Sundararaj. 2002. Sugarbeet cyst nematode management options in Idaho. Proceedings of the University of Idaho Winter Commodity Schools  2002. 231-236. Hafez, S.L., P. Sundararaj, and B. A. Hatjian. 2002. Evaluation of nematicides for the management of Columbia root-knot nematode in potato, 2001. Fungicide and Nematicide Tests 57:N10. Hafez, S.L., P. Sundararaj, and B. A. Hatjian. 2002. Fosthiazate 500 EC for control of Columbia root-knot nematode in potato, 2000. Fungicide and Nematicide Tests. Fungicide and Nematicide Tests. 57:N11. Hafez, S.L., P. Sundararaj, and B. A. Hatjian. 2002. Nematicides for the management of Columbia root-knot nematode in potato, 2001. Fungicide and Nematicide Tests. 57:N13. Hafez, S.L., P. Sundararaj and D. Miller. 2002. Reaction of twenty one alfalfa cultivars to the lesion nematode Pratylenchus penetrans and the root knot nematode Meloidogyne chitwoodi. Proceedings of the North American Alfalfa Improvement Conference held at Sacramento, California from July 27 to 31, 2002. Hafez, S.L., P. Sundararaj, and R. Portenier. 2002. Application and placement of Temik, Vydate and Admire for control of stubby root nematode and corky ringspot disease of potato, 1999. Fungicide and Nematicide Tests. 57:N09. Hafez, S.L., P. Sundararaj, and R. Portenier. 2002. Fosthiazate 900 EC for control of Columbia root-knot nematode in potato, 1998. Fungicide and Nematicide Tests. 57:N12. Hall, A.E., N. Cisse, S. Thiaw, H.O.A. Elawad, J.D. Ehlers, A.M. Ismail, R.L. Fery, P.A. Roberts, L.W. Kitch, L.L. Murdock, O. Boukar, R.D. Phillips and K.H. McWatters. 2003. Development of Cowpea Cultivars and Germplasm. Field Crops Research 82:103-134. Held, L.J., T.J. Opp, D.W. Koch, F.A. Gray and J.W. Flake. 2003. Profitability of variable versus uniform rate nematicide for sugar beets. Journal of ASFMRA, pp. 74-83. Hurchanik, D., D.P. Schmitt, N.V. Hue, and B.S. Sipes. 2003. Relationship of Meloidogyne konaensis population densities to nutritional status of coffee roots and leaves. Nematropica, 33:55-64. Luna, E., J. Schroeder, S.H. Thomas and L.W. Murray. 2003. Purple nutsedge growth and biomass partitioning in response to root-knot nematodes. Proceedings, Western Society of Weed Science 56:36. McSorley, R. and S.H. Thomas. 2003. Root-knot nematodes. Pp. 46-47. In: Compendium of Pepper Diseases. K. Pernezny, P. A. Roberts, J. F. Murphy, and N. P. Goldberg eds., APS Press. St. Paul, MN. Melakeberhan, H. and J. Dey. 2003. Competition between Heterodera glycines and Meloidogyne incognita or Pratylenchus penetrans: Independent infection rate measurements. Journal of Nematology, 35: 1-6. Riga, E., Mojtahedi, H., Ingham R.E. and A.M. McGuire. 2003. Green manure amendments and management of root knot nematodes on potato in the Pacific Northwest of USA. Nematology Monographs and Perspectives. 2: 151-158. Smith, H.J., F.A. Gray and D.W. Koch. 2003. Evaluation of resistant trap crop radish cultivars for control of the sugar beet cyst nematode, Heterodera schachtii. Phytopathology 93:S80. Thomas, S.H., J. Schroeder, J.M. Fuchs, C. Fiore, I. Ray, and L.W. Murray. 2003. The efficacy of alfalfa as a rotation crop for simultaneous suppression of Meloidogyne incognita and nutsedges. Journal of Nematology 35:366 (abstr.).