Brief Summary of Minutes of Annual Meeting

Through extensive and multiple collaboration among scientist in and outside of the project, we have contributed to the better understanding of nematode variability and nematode control. Meloidogyne hapla populations differ in their susceptibility to the endoparasitic fungus Hirsutella minnesotentsis but arugula (Eruca sativa, potential trap crop) inhibits their development. The entomopathogenic nematodes Steinernema feltiae and S. glaseri Meloidogyne javanica by varying degrees. In combination with the nematode trapping fungi Arthrobotrys oligospora, S. feltiae gave less nematode reproduction, however, no such enhancement was observed with S. glaseri. Dihydromaltophilin apparently acts in nematode biocontrol by the bacteria Lysobacter enzymogenes C3, affecting nematode motile stages, whereas other mechanisms affect nematode reproduction. Most plant-parasitic nematodes are soil borne, therefore the soil environment is extremely important. Heterodera glycines, the soybean cyst nematode, differs in adaptation to soil conditions. The reproductive potential M. hapla is influenced by soil type and possibly soil input. Pre-plant irrigation may be manipulated to moderate heat unit accumulation and thus affect hosts and reproduction of M. incognita. A fertilizer-use efficiency model that describes an integrated approach to distinguishing agronomic, ecological, and economic aspects for a range of nematode management practices has been developed. The model will soon incorporate the physio-chemical impact of organic and inorganic soil amendments. Irrigation water requires ozonation from 15 to 55 minutes to control a range of plant-parasitic nematodes. Plants, and the subsequent interactions that nematodes have with them, are an equally important aspect of nematode variability. Yellow and purple nutsedges are weed hosts of M. incognita races 1-3 and M. javanica, but do not appear to host M. hapla as previously reported. All of the common sorghum, sudangrass or sorghum/sudangrass hybrids currently grown in New Mexico support sufficient M. incognita reproduction to be unsuitable as rotation crops for suppression of the root-knot nematode/yellow nutsedge/purple nutsedge pest complex. A two-year rotation of M. incognita-resistant alfalfa cultivar Mecca II following nematode-susceptible chile peppers reduced both the frequency and density of M. incognita. Host-plant resistance in soybean to H. glycines is used for control, yet over use and result in a change in nematode virulence. Resistant cultivars Anand showed decreases in nematode numbers in all its plots, whereas Minokin and Hucheson increased in all their plots. AG 5501 gave mixed results. SO2-3934-RR reduced nematode populations while HBK R 4946 CX and HBK 4924 increased H. glycines populations. In Lima bean, resistance to M. incognita and M. javanica was found to be based on three independent genes. A combination of both galling and reproduction resistance genes provides high levels of protection from nematode yield suppression in bush and vine lima beans. A major M. incognita R gene, rkn1, was identified on chromosome 11 in the upland cotton (Gossypium hirsutum) Acala NemX. Oil radish cultivars like Comet used as a cover crop can control M. chitwoodi damage to potato. Many nematodes can be managed with crops currently grown or available. In the potato and Meloidogyne chitwoodi system, excellent host crops can be grown early rather than late in a rotation to provide control. Arugula, Eruca sativa, was not able to reduce M. chitwoodi populations, however, Arugula + ½ Telone reduced M. chitwoodi populations to undetectable levels. With long season potato cultivars grown in warm regions, rotation may need to be augmented with nematicides. Combining a green manure with a reduced rate of a nematicide has economical potential. Management of Meloidogyne chitwoodi with rotation may be more successful with shorter season cultivars or in cooler climates. Green manures of the sorghum x sudangrass hybrid Sordan 79 and sunn hemp reduced populations of Meloidogyne javanica and increased taro corm weight. A collaborative morphological and molecular identification of a rediscovered, unidentified cyst nematode found in corn in western Tennessee is being linked to host range and distribution. Research has not yet linked soybean cyst nematode genes regulating pharyngeal proteins and proteins involved in reproduction with virulence. Caenorhabditis elegans strain N2 is the standard wild-type yet differs in important demographic properties such as mortality, fertility, fitness, and activity patterns from recently collected wild-type strains suggesting adaptation to laboratory conditions. In order to address industry needs and in response to grower requests, the project has undertaken several research initiatives. Results have been disseminated to groups through multiple venues. Growers and industry clientele are given presentations across the western region. Results were transferred to scientific peers through presentations and peer-reviewed publication, totaling 52. The project has continued to refine tools that growers can use to effectively manage root-knot and cyst nematodes in a sustainable and environmentally friendly manner. Natural host plant resistance genes, nonhost cover crops, and biological agents are valuable in crop plants as effective and safe approaches to managing plant-parasitic nematodes. The combined results of our project continue to demonstrate that site-specific, rather than one-size-fits-all management approach will be applicable. This regional project has impacted agricultural producers, fellow scientists, and agricultural consultants.