Annual/Termination Reports:

[01/20/2004] [01/08/2005] [02/09/2006] [12/19/2006] [01/02/2008]

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Participants

Powers, Tom (tpowers1@unl.edu), University of Nebraska; Donald, Pat, (pdonald@ars.usda.gov), USDA-ARS; Ingham, Russ (inghamr@science.oregonstate.edu), Oregon State University; Thomas, Steve (stthomas@nmsu.edu), New Mexico State University; Gray, Fred (fagray@uwyo.edu), University of Wyoming; Hafez, Saad (shafez@uidaho.edu), University of Idaho; Melakeberhan, Haddish (melakebe@msu.edu), Michigan State University; Sipes, Brent (sipes@hawaii.edu), University of Hawaii; Caswell-Chen, Ed (epcaswell@ucdavis.edu), University of California, Davis; Hyman, Brad (bradley.hyman@ucr.edu), University of California, Riverside; Roberts, Philip (philip.roberts@ucr.edu), University of California, Riverside; Riga, Ekaterini (riga@wsu.edu), Washington State University; Cooksey, Don (Donald.Cooksey@ucr.edu), Administrative Advisor, UC Riverside

Brief Summary of Minutes

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.

Accomplishments

Objective 1. Characterize genetic variability as related to PPN responses to resistance, environment, biological processes, and morphology.<br /> <br /> 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. <br /> <br /> Objective 2. Determine nematode fitness and adaptability relative to environment, host plant, and host resistance.<br /> <br /> 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.<br /> <br /> Objective 3. Design and develop management strategies for cyst and root-knot nematodes relative to genetic variability.<br /> <br /> 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.<br />

Publications

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.<br /> <br /> Bosland, P.W., Y. Zewdie, and S.H. Thomas. 2003. NuMex Nematador, southern root-knot resistant cayenne pepper. HortScience 38:631-632.<br /> <br /> 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.).<br /> <br /> 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.).<br /> <br /> Chen, P. and P.A. Roberts. 2003. Virulence in Meloidogyne hapla differentiated by resistance in common bean (Phaseolus vulgaris). Nematology 5:39-47. <br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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. <br /> Development of Cowpea Cultivars and Germplasm. Field Crops Research 82:103-134.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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.<br /> <br /> Riga, E., Mojtahedi, H., Ingham R.E. and A.M. McGuire. 2003. Green manure<br /> amendments and management of root knot nematodes on potato in the Pacific <br /> Northwest of USA. Nematology Monographs and Perspectives. 2: 151-158.<br /> <br /> 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.<br /> <br /> 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.).<br />

Impact Statements

1. *Crop rotation with nematode-resistant alfalfa could replace soil fumigation in chile pepper production for control of both nutsedge and the southern root-knot nematode.
2. *Effective biological control with the soil fungus Hirsutella minnesontesis, could reduce or replace methyl bromide soil fumigation for control of the Northern root-knot nematode in the U.S. .
3. *GPS site specific, variable rate application of Telone II can be more economical and less polluting in controlling the sugar beet and soybean cyst nematodes than the standard uniform rate application currently employed in the U.S..
4. *Better understanding of field populations of the coffee root-knot nematode will prolong utility of resistance coffee rootstock and increase earnings of coffee producers on the big island of Hawaii..
5. *More accurate standardized greenhouse assays of soybean lines to races of the soybean cyst nematode will result in increased soybean yields in the U.S.
6. *Use of a molecular bar code for the Northern root-knot nematode will expedite export of U.S. potato shipments resulting in increased earnings of U.S. producers.
7. *Knowledge was gained for predicting risk of nematode virulence development following introduction of resistant crop varieties.
8. *Use of green manure crops and organic nematicides may reduce use of synthetic nematicides in controlling root-knot nematodes.

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Participants

Caswell-Chen, E. (epcaswell@ucdavis.edu) - UC Davis; Donald, P. (pdonald@msa-stoneville.ars.usda.gov) - USDA-ARS; Gray, F. (fagray@uwyo.edu) - U. Wyoming; Hafez, S. (shafez@uidaho.edu) - U. Idaho; Ingham, R. (ingham@science.oregonstate.edu) - Oregon State Univ.; Melakeberhan, H. (melakebe@msu.edu)- Michigan State Univ.; Powers, T. (tpowers@unl.edu) - U. Nebraska; Riga, E. (riga@wsu.edu) - Washington State Univ.; Sipes, B. (sipes@hawaii.edu) - U. Hawaii

Brief Summary of Minutes

Accomplishments

Not all nematodes behave in the same fashion in response to different control tactics because nematodes are a genetically variable group of organisms. It is often important to be able to differentiate among nematode populations. It may soon be possible to identify nematodes species using a small section of the 3 region of the 18S rDNA as a DNA barcode.<br /> <br /> <br /> Host plant resistance is an important tool for sustainable nematode control. The root-knot nematode resistant/tolerant sainfoin Shoshone has been released by the University of Wyoming allowing increased stand persistence in root-knot nematode infected areas. Two hundred twenty soybean varieties have been evaluated for resistance to the soybean cyst nematode Race 3 HG type 0 providing growers and commercial breeders valuable data necessary to manage the nematode. For soybean cyst nematode resistance evaluations, replications in time is better for assessing nematode reproduction than more replications conducted at the same time. Alfalfa varieties have been screened for resistance to lesion nematode and root-knot nematode. Bean cultivars have been evaluated for resistance to the northern root-knot nematode. Sugar beet genotypes have been screened for resistance/tolerance to the sugar beet cyst nematode and a wild-type beet with tolerance was identified. In taro, no absolute resistance to root-knot nematode, but a range of tolerance and susceptibility was identified among germplasm.<br /> <br /> <br /> With a general interest in lowering fumigant costs for nematode control, cover crops are one possible alternative. A blend of mustards used as a cover crop following a wheat rotation worked well in controlling root-knot nematode in potato in the Northwest. Arugala Nemat is a potentially good as a cover crop because it works as a trap crop luring the nematode into roots but not supporting reproduction. For more tropical systems, sorghum/sudangrass hybrids, marigolds, and sunn hemp are cover crop possibilities. These rotations must be sensitive to grower concerns and amenable to the existing cropping system.<br /> <br /> <br /> Whereas resistance and the use of nonhost plants serve to take advantage of differences in genetic variability among nematodes to protect crop plants, other methods can be used to control nematodes as well. Lysobacter enzymogenes strain C3 is active against a range of plant-parasitic nematodes. This bacteria has the potential to be a new nematode biological control agent. Soybean cyst nematode populations appear to differ in their adaptation to soil environments. Consequently, N-Viro Soil, a recycled municipal biosolid product, could be used as a soil amendment to take advantage of the differences in nematode adaptation and be a complimentary or alternative for resistance management. <br /> <br /> In the coming year, our project activities will focus on completion of several experiments, initiation of new experiments, and continuation of exisiting experiments. We will evaluate plant germplasm for sources of resistance to nematodes. We will be conducting experiments to determine the genetic variation underlying observed nematode behavior. We will be investigating new methods to control nematodes which exploit the underlying variation in nematodes and there interactions with plants. We will undertake efforts to draft proposals to fund ongoing and new research endeavors. <br /> <br />

Publications

Impact Statements

1. Detailing sources of host plant resistance to nematodes in different crop plants
2. Finding faster, easier methods to identify nematodes
3. Providing effective, environmentally sustainable nematode control options

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Participants

See minutes of annual meeting.

Brief Summary of Minutes

Accomplishments

Plant-parasitic nematodes continue to cause substantial yield loss in many crops. Control is often difficult because of underlying genetic variability. Several approaches, including host-plant resistance, nematicide application, and biologically means, can be employed to control these pests. This project has demonstrated the potential success of each method. <br /> <br /> Host-plant resistance has been demonstrated in sugar beet, cowpea, lima beans, and taro. Syngenta sugarbeet cultivars HM 1334 and 'Nematop' were resistant to H. schachtii. In an increasing number of soybean fields, host-pant resistance is not protecting from the risk of yield loss. Despite this trend, few soybean lines coming through the USDA Southern Regional Program are resistant to any of the standard soybean cyst nematode races. Natural host plant resistance genes are valuable in crop plants as effective and safe approaches to managing nematodes. Genetic variability in nematodes for ability to reproduce on resistant plants is being characterized to help guide decisions on use of resistant crop varieties and to give direction to plant breeding programs for grain legumes. Cowpea and lima beans can best be protected with resistance genes against nematode reproduction and nematode galling. <br /> <br /> Every thing old is new again for chemical nematode control. Whereas old organophosphate nematicides are leaving the market, equally old product are finding renewed utility. This project has demonstrated the Abamectin seed treatments can be effective in reducing damage caused by nematodes. Ozone is a powerful oxidizing agent and has been shown to be an effective fungicidal and bactericidal agent when injected into water. Caenorhabditis elegans exposed to aqueous ozone concentrations of 0.12 ppm killed almost all nematodes within 15 minutes. The efficacy of Vydate can be improved by exploiting nematode development and behavior.<br /> <br /> Biological control with cover crops, fungi, and bacteria. Cover crops were tested for their ability to control damage to sugar beet, potato, and taro. Green manures of 'Defender' and 'Comet' radishes were effective against M. chitwoodi. Chitinolytic microflora may contribute to biological control of plant-parasitic nematodes by causing decreased egg viability through degradation of eggs. Some cover crops that are appropriate for one rootknot nematode may not be so good for a different species of rootknot nematode. In tropical systems, sorghumXsudan grass hybrids appear to be best for M. javanica. Lysobacter enzymogenes strain C3 killed Caenorhabditis elegans, Heterodera schachtii, Meloidogyne javanica, Pratylenchus penetrans, and Aphelenchoides fragariae in in vitro experiments. Tungus Hirsutella minnesotensis suppressed populations of M. hapla populations from 5 states by 61-98%. Weeds are often overlooked as inoculum sources, however their potential to increase nematode damage has been reconfirmed. Yellow nutsedge is a host for M. hapla and the previously?established association between nutsedges and M. incognita appears to extend to other species of Meloidogyne.<br /> <br /> Nematode genetics play a key role in plant parasitic nematodes interactions with the host. Consequently, understanding nematode genetics will allow us to develop better controls. Populations of M. hapla differ in their pathogenecity based on the environment from where they originate. Whether or not there are intra?population genetic differences or how much the differences in soil conditions contributed to the results are yet to be determined. Wild-type strains of C. elegans may not always be so "wild." C. elegans is not common in California soil, compost piles, garden soils high in organic matter, mushrooms, or surface layers of forest floors. They are found associated with snails. The nature of the snail-nematode interaction, and the genetics, ecology and demography of wild isolates are being investigated. Over 400 partial 18S sequences have been added to GenBank and others laboratories by this project. The 3' barcode used to establish that litter, soil, and understory habitats have a large proportion of unique nematode sequences and nematode diversity is greatest in the litter.<br /> <br /> In the coming year, our project activities will continue to focus on evaluation of plant germplasm for sources of resistance to nematodes, identifying sustainable . We will be conducting experiments to determine the genetic variation underlying observed nematode behavior. We will be investigating new methods to control nematodes which exploit the underlying variation in nematodes and there interactions with plants. We will undertake efforts to draft proposals to fund ongoing and new research endeavors.

Publications

Impact Statements

1. The combined results of our project suggest that site?specific, rather than "one-size-fits-all management approach" will be applicable.
2. Studies on the specificity, efficacy of host plant resistance, biological controls, and nematode genetics and their use in cropping systems will advance their utilization in American agriculture.
3. sources of host plant resistance to nematodes in cowpea, lima beans, sugarbeets, and taro will aid efforts to breed nematode resistance.
4. Host plant resistance and biological control is providing effective, environmentally sustainable nematode control options.
5. Studies on nematode genetics is providing scientists with basic information on nematode biology that can lead to novel control strategies in the future.

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Participants

See Meeting Minutes

Brief Summary of Minutes

Accomplishments

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. <br /> <br /> 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.<br /> <br /> <br /> 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.<br /> <br /> 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.<br /> <br /> 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. <br /> <br /> 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. <br /> <br /> 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. <br />

Publications

Impact Statements

1. Natural host plant resistance genes are valuable in crop plants as effective and safe approaches to managing root-knot nematodes, and sutdies on their specificity, efficacy and use in cropping systems advance their utilization in agriculture.
2. Genetic variability in nematodes for ability to reproduce on resistant plants is being characterized to help guide decisions on use of resistant crop varieties and to give direction to plant breeding programs for grain legumes and cotton.
3. Tools are being defined that growers can use to effectively manage root-knot nematodes in a sustainable and environmentally friendly manner. Entomopathogenic nematodes suppression of M. javanica can be enhanced the use of nematode trapping fungi. Green manure cover crops are available and are being used by growers to control root-knot nematodes.
4. Crop rotation with a nematode-resistant alfalfa cultivar was shown to effectively reduce the frequency and density of the nematode pest, M. incognita in New Mexico.
5. Columbia root-knot nematode can be managed with rotational crops currently grown in the Columbia Basin of OR and WA if excellent host crops were grown early rather than late in the rotation.
6. In long season potato cultivars grown in warm regions, a green manure treatment can be combined with reduced rates of nematicides to control plant parasitic nematodes in fields with high nematode densities.

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Participants

See attached Summary of Minutes.

Brief Summary of Minutes

Accomplishments

The project has four objectives. Many aspects of the work conducted and accomplishments of the project are in response to grower inquiries. The project activities are diverse and cover a wide range avenues - made possible by the very multi-state nature of the regional project. Project scientists are involved in research spanning the basic to the applied. Our accomplishments will be organized and reported under each of the four project objectives.<br /> <br /> Defining nematode genetic variability <br /> <br /> Managing pests with high genetic variability, which includes many plant-parasitic nematodes, diverse agro-ecosystems has many challenges. One aspect of variability is fecundity or the reproductive potential of the nematodes. An other aspect is the consistency between laboratory/greenhouse behavior and field behavior of the nematodes. The reproductive potential of Meloidogyne hapla from mineral soil was higher than those from muck soil, and was positively correlated with the soil pH from where the nematodes came. As measured by nematode community structure indices, a muck soil had better nutrient availability and energy channels than a loamy sand soil. Difference in reproductive potential between the loamy sand and the muck soil nematode populations suggests that nematode adaptation may need to be considered in identifying nematode populations. The fecundity of Meloidogyne incognita host race 3 derived from a single, field-isolated population that was subsequently cultured on yellow nutsedge (Cyperus esculentus = YNS), purple nutsedge (C. rotundus = PNS), or chile pepper (Capsicum annuum cv. NM 6-4) and then tested on chile was not affected by inoculum source. However, inoculum from YNS or PNS resulted in lower levels of reproduction on chile than did inoculum that had been produced on chile. Plant species within a host/weed pest complex influence nematode virulence among species, as does weed/crop competition. Greenhouse screening to identify resistance to nematodes like Heterodera glycines, the soybean cyst nematode (SCN), is expected to be consistent and representative of field conditions. Comparison of reactions over time can be problematic because breeding lines are transient in testing programs. Of 186 soybean lines compared in the uniform and preliminary IVS from 2004 through 2006 only three lines were present for all 3 years and just seven lines were present for 2 years. Comparison of these lines found consist ratings in 90% of the lines over time.<br /> <br /> A comparative mitochondrial genomics study has shed understanding on the molecular evolutionary mechanisms giving rise to the unusual structural features found within the mitochondrial genome of the mosquito parasitic nematode Romanomermis culicivorax. Multiple mitochondrial DNA haplotypes of Thaumamermis cosgrovei, parasites of the isopod Armadillidium vulgare, are maintained in local isopod populations with a magnitude and frequency of mtDNA haplotype variation unprecedented among metazoan mitochondrial genomes. Genetic analysis revealed that multiply infected hosts are the result of co-parasitization by members of the same maternal lineage, and not the result of spatially and temporally independent infections. A novel mermithid nematode mtDNA haplotype within A. vulgare was found and identified as an Agamermis sp. based on both morphological and molecular phylogenetic analyses. Complete sequences of mitochondrial geneomes frm T. cosgrovei, Agamermis sp., and the mosquito mermithid nematode Sterlkovimermis spiculatus have been determined and compared to Romanomermis revealing a number of unusual features of mermithid mitochondrial genomes. Mermithids have frequent and large-scale size polymorphism, lengthy repeating sequences, inversion of repeating units, extensive duplication of coding genes, and rapid rearrangement. Characterization and analysis of mermithid mitochondrial genomes has also expanded our understanding of the differences between mtDNAs from the Chromodorea and the Enoplea. In contrast to the recurrent mitochondrial gene syntenic relationshiops typifying the Chromodorea, remarkably divergent mitochondrial gene orders are observed at all taxonomic levels (subfamily, genus, species) among the Enoplea. To place Enoplean mtDNA in a phylogenetic context, a molecular framework was constructed from selected mermithid species based on 18S nuclear rDNA sequences. This effort provided the first molecular phylogeny for this nematode family. Topology of the molecular framework is reminiscent of the only previously hypothesized systematic treatment for mermithids, based exclusively on morphology and life history traits. The molecular phylogeny was instrumental in identifying a new mermthid parasite, Allomermis solenopsi, of the fire ant Solenopsis invicta.<br /> <br /> Determining nematode fitness and adaptability <br /> <br /> Plant-parasitic nematodes are surprisingly adaptable creatures, surviving long distance transport and what might be considered severe environmental conditions. This adaptability of plant-parasitic nematodes increases challenges producers face in controlling them. Nematodes may be transported in agricultural irrigation water which poses serious control/production challenges when recycled water is used. Ozone and pulsed-ultraviolet light (PUV) are two possible treatments to rid the water of nematodes. Ozone, a powerful oxidizing agent, was equilibrated at concentrations of 0.08, 0.18, 0.215, and 0.38 ppm. The survival of Caenorhabditis elegans, Aphelenchoides fragariae, Heterodera schachtii, and Meloidogyne species differed. A. fragariae became inactive in 20 min at a CT value 7.8 ppm/min and M. incognita in 15 min at a CT value 3.6 ppm/min. The CT values required to consistently obtain 90% kill ranged from 2-8 ppm/min, regardless of nematode species. Higher exposure CT values were required for inactivation in recycled irrigation water. M. javanica became inactive in 75 min at a CT value of 12 ppm/min and C. elegans in 30 min at a CT value of 1.5 ppm/min. Nematodes were exposed to a range of UV doses. PUV at 372 mJ/cm2 immediately inactivated M. javanica juveniles. Inactivation of A. fragariae required 425 mJ/cm2, C. elegans: 460 mJ/cm2, and Acrobeloides buetschii: 407 mJ/cm2.<br /> <br /> Because nematodes vary in their response to a host, resistance and tolerance to plant-parasitic nematodes in crop plants is important to understand. Ten alfalfa genotypes were screened for tolerance to the lesion nematode, Pratylenchus penetrans. Ts5000 had increased fresh and dry weight of shoot and root followed by the lowest level of P. penetrans populations. The reproduction of M. hapla differs on oil radish and arugula cultivars. Among those tested, Lebanese (Racola, 91.4%) and oil radish (Defender, 95.0%) had the highest nematode reproduction. In another study, using the cultivars Comet, Defender, and Accent as green manures increased total potato tuber yield compared to fallow. Tests in Michigan with oilseed radish, Raphanus sativus, used as a trap, cover, or biofumigant, demonstrated potential for managing M. hapla. However, exploiting the multi-purpose traits of oilseed radish requires careful understanding of M. haplas reproductive fitness in the prevailing soil conditions. When populations of M. hapla were tested in muck, loamy sand and sandy soils, they completed their life cycle in oilseed radish in approximately 500 degree days (DD, base 10oC). Thus, suggesting that oilseed radish cultivars that are hosts to M. hapla may be best used as trap crops and plants destroyed before the nematode completes a life cycle. The host status of M. incognita on pearl and ornamental millet (Pennisetum glaucum), giant bermudagrass (Cynodon dactylon), and switch grass (Panicum virgatum), potential rotation crops with vegetables and cotton in New Mexico, were evaluated. All except ornamental millet supported less nematode reproduction than the best sorghum-sudangrass cultivars examined in 2006, with pearl millet and switch grass showing the greatest promise as candidates for suppression of M. incognita and potentially the root-knot nematode/nutsedge pest complex. Certain ornamental annuals and medicinal plants are do not seem to be good hosts to M. incognita and might provide organic vegetable producers with alternative rotation crops for root-knot nematode suppression. <br /> <br /> Plant-parasitic nematodes can be introduced into new areas and new infestations are always discovered. It is important to identify this infestations, their extent, and the biology of the nematodes. Potato cyst nematodes Globodera rostochiensis and G. pallida are significant economic threats to food production, so a comprehensive statewide detection survey documented the absence of G. rostochiensis in Idaho but confirmed the presence of G. pallida in Idaho. Relatively low levels of infestation of the previously established Northern root knot nematode, Meloidogyne hapla (0.6%), and the Columbia root knot nematode, M. chitwoodi (2.9 %), were found in Idaho. In 2006, a Cactodera population was discovered on corn in Tennessee. Tests have revealed that this cyst nematodes host range is centered on corn with little to no reproduction on other grasses and no reproduction on dicots tested. A survey for distribution of the nematode is ongoing. An infestation of the soybean cyst nematode, H. glycines, was identified on Kauai in Hawaii. The infestation was limited in distribution to an area of intense soybean production. A population of root-knot nematode infecting Citrus × paradisi, grapefruit, has been tentatively identified as Meloidogyne javanica. The nematode is reproducing well (3000 to 5250 J2/250 cc soil) on citrus with galling clearly visible on the citrus roots as well as nearby koa (Acacia koa). Females inside the galls were large and plump but their egg masses seemed to contain fewer eggs than would be expected on a good host like tomato. <br /> <br /> <br /> Designing and developing integrated management strategies for plant-parasitic nematodes <br /> <br /> Rotations and host-plant resistance continue to provide appropriate levels of nematode control and offer sustainable long-range solutions for nematode control. In Arkansas, a rotation study of 3 soybean resistance sources; Soybean cyst nematode resistance from Peking (Minokin), PI-88788 (Ag5501), and PI-437654 (Anand) have been rotated after each of the other resistant varieties and grown each year with no rotation as checks along with susceptible Hucheson with and without nematicide. In 2007, Anand showed decreases in SCN numbers, whereas Minokin and Hucheson increased in all their plots. AG 5501 gave mixed results. The field was originally tested as SCN race 6. In a second rotation using Roundup Ready and the resistance sources PI88788 (Ag 5501), SO2-3934-RR a recently released line form Missouri with PI-437654 resistance, and HBK R 4946 CX with Cystex resistance, all resistant lines reduced nematode populations compared to 2006. In Idaho, a long term crop rotation indicated that sugar beet yield increased with green manure crops of Defender and Comet oil raddish compared to fallow. Short term rotation study showed that there was a significant increase in beet yield in the green manure planted plots as compared to fallow. Maximum yield (T/A) was with the Luna (37.0) planted plots followed by the Defender(36.0) plots. When host-plant resistance is not available in a crop it is now possible to employ genetic engineering to incorporate nematode resistance into the plant. Protease inhibitors (cystatins) have been incorporated into anthuruim, coffee, and pineapple. In anthurium, burrowing nematode reproduction and body volume was reduced in putatively cystatin-transformed plants compared to the wild-type plants. The addition of cystatin to coffee via bombardment reduced root-knot nematode population by over 70% in the transgenic plants. Pineapple transgenic with a cystatin gene has greater resistance to root-knot nematode infection that the wild type pineapple.<br /> <br /> Control of plant parasitic nematodes and enhancement of beneficial free living nematodes is essential to quality crop production and protection of the environment in the USA. Columbia root-knot nematode, Meloidogyne chitwoodi, management in potato has relied on soil fumigants and non-fumigant nematicides alone or in combination. Bionematicides and trap crop/green manures on their own and in combination with reduced rates of nematicides have been tested against M. chitwoodi, Pratylenchus penetrans, and Paratrichodorus allius. Brassica trap crops in combination with half the recommended rate of the fumigant Telone, reduced populations of M. chitwoodi from 700 nematodes/250cc soil to zero, below the economic threshold of 1 nematode/250cc soil; and reduced P. penetrans and P. allius below economic thresholds as well. In contrast, the combination treatments did not reduce the beneficial free-living nematode populations. The tentative cost of growing and incorporating trap crops/green manures in combination with reduced rates of nematicides was approximately half the present commercial cost of fumigants. Green manure crops can be successful but requires different management strategies in different climatic environments. In long, warm production areas, such as those that occur in the Columbia Basin of Oregon and Washington, season length is long enough that a short season crop such as wheat or sweet corn can be followed by green manure crops planted in late summer and incorporated in late fall. While this strategy can reduce populations of M. chitwoodi substantially, the long growing season and warm soil temperatures during the following potato crop permit the small populations that remain to increase sufficiently to still cause tuber damage. In areas with short, cool growing seasons, such as those that occur in the San Luis Valley (SLV) of Colorado, season length is not long enough for a green manure crop to be planted after a grain crop. High nematode control costs relative to crop value, low grain prices, and water shortages led to grower interest in growing green manure crops during the summer instead of a grain crop to reduce water use, improve soils, and reduce nematode control costs. In long season areas, green manure crops need to be augmented with other strategies such as reduced nematicide applications or by proceeding the green manure crops with a poor or non-host rotation crop. In short season areas, green manure crops appear to be sufficient to control M. chitwoodi without other strategies to augment suppression. Trace amounts of tuber infection were found when tubers were incubated, so green manure crops should not be the sole control for potato intended for seed or export. The biocontrol agent Muscodor albus which produces fumigants with nematicidal properties resulted in nematode mortality of 82.9% for P. allius, 82.1% for P. penetrans, and 95% for M. chitwoodi compared to mortality in the nontreated controls of 9%, 7%, and 3.9% respectively. <br /> <br /> Green manures are not the only sustainable nematode control option being evaluated by the project. The effects of animal wastes like dried-screened poultry litter and beef manure at 0, 5, and 10 t/a on SCN reproduction are being evaluated.. SCN reproduction was significantly lower in both beef manure treatments and the poultry litter at 10 t/a than the control treatment with no animal waste.<br /> <br /> Producers still often seek a quick fix to nematode diseases, like those provided by chemical applications. Chancellor and the WD at the applied rate significantly increased the total potato tuber yield and reduced the percent of nematode infected tubers. The new product STAN was not as effective as Temik in controlling damage from the sugar beet cyst nematode. <br /> <br /> Efforts are also being directed at developing predictive tools to aid in controlling nematodes. A fertilizer-use efficiency (FUE) model (which describes an integrated approach to distinguishing agronomic, ecological, and economic implications of nematode management practices) has improved with the incorporation of a daily nematode population density (DNPD = (Sum of nematode population density per unit of root plus soil from planting to end of sampling date) / the number of days from planting to last sampling date). Among other aspects, DNPD can be used to test for correlations with physiological changes overtime. Relating yield and/or physiological measurements data to DNPD is a step towards developing measurable nematode threshold levels over a growing season rather than at one point in time. Visual indicators can also have a roll in assessing potential nematode damage. In a rotation test of chile pepper and non-dormant, M. incognita-resistant alfalfa (cultivar Mecca II), nutsedge counts in fields infested with the M. incognita-nutsedge pest complex can be used as a visual predictor of J2 populations, unless the number of nutsedge plants is very low. <br /> <br /> <br /> Implementing rapid information transfer to stakeholders<br /> <br /> Research results were disseminated to different user groups through multiple venues during 2006-2007. Scientific peers were updated and informed of new discoveries through presentations at annual professional meetings and at commodity meetings. Discoveries and accomplishments were published in a variety of peer-reviewed and popular outlets. Results were transferred to agricultural producers, crop consultants, and county agents at through formal presentations at conferences and field days with oral and poster presentations.<br />

Publications

http://eppserver.ag.utk.edu/Extension/SPDN/2007/Cyst-nematode-corn/Cyst-Corn.html <br /> <br /> Boydston, R. A., Mojtahedi, H., Brown, C.R., Anderson, T., and E. Riga. 2007. Hairy Nightshade Undermines Resistance of Potato Breeding Lines to Columbia Root-Knot Nematode. The American Journal of Potato Research. 84:245-251<br /> <br /> Cabos, R.M., B.S. Sipes, D.P. Schmitt, H. J. Atkinson, C. Nagai. 2007. Plant proteinase inhibitors as a natural and introduced defense mechanism for root-knot nematodes in Coffea arabica. Journal of Nematology 39:100.<br /> <br /> Collins, H.P., Navare, R., E. Riga and F.J. Pierce. 2006. Effect of foliar applied plant elicitors on microbial and nematode populations in the root zone of potato. Communications in Soil Science and Plant Analysis 37:1747-1759.<br /> <br /> Donald, P.A., Kilen, T., and Mengitsu, A. 2007. Registration of soybean germplasm line D99-2018 resistant to Phytophthora rot (Rps6) and soybean cyst nematode races 3 (HG Type 0) and 14 (HG Type 1.3.6.7). Crop Science. 47:451-452.<br /> <br /> Donald, P.A., Hayes, R., and Walker, E. 2007. Potential for soybean cyst nematode reproduction on winter weeds and cover crops in Tennessee. Online. Plant Health Progress do8i:10.1094/PHP-2007-0226-01-RS.<br /> <br /> Hafez, S.L.; P. Sundararaj; Z. A. Handoo; A. M. Skantar; L. K. Carta and D. J. Chitwood. 2007. First Report of the Pale Cyst Nematode, Globodera pallida, in the United States. Plant Disease. 91 : (3). pp. 325. <br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Evaluation of fumigant and nonfumigant nematicides for the control of Meloidogyne chitwoodi in potato. Nematologia Mediterranea. 34: 145-147.<br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Efficacy of applications of aldicarb at plant and post plant for control of Heterodera schachtii on sugar beet. International Journal of Nematology. 16: 2, 153 -156.<br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Efficacy of nemathorin for the control of Paratrichodorus spp. and Meloidogyne chitwoodi in potato. International Journal of Nematology. 16: 2, 157-160. <br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Chemical nematicides efficacy for the management of Meloidogyne chitwoodi on potato in Idaho. Presented at the Annual Meeting of the Society of Nematologists held at Kauai, Hawaii from June 19-21, 2006.<br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Biofumigation  An alternative approach for the management of Meloidogyne chitwoodi on potato in Idaho. Presented at the World Potato Congress held at Boise, Idaho, USA from August 20-26, 2006.<br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Use of chemical nematicides in the management strategy of Columbia root knot nematode, Meloidogyne chitwoodi on potato in Idaho. Presented at the World Potato Congress held at Boise, Idaho, USA from August 20-26, 2006.<br /> <br /> Hafez, S.L. and P. Sundararaj. 2006. Green manure crops evaluation for the suppression of Meloidogyne chitwoodi and Heterodera schachtii. Presented at the Annual Meeting of the Society of Nematologists held at Kauai, Hawaii from June 19-21, 2006.<br /> <br /> Ingham, R.E., M. Dillon, N.L. David, and J. Delgado. 2007. Using green manure crops to suppress Columbia root-knot nematode (Meloidogyne chitwoodi) in potato in the San Luis Valley. Journal of Nematology 39:93.<br /> <br /> Khaithong, T., B.S. Sipes, and A.R. Kuehnle. 2007. Transgenic Anthurium andraeanum expressing modified rice cysteine protease inhibitor and resistance to Radopholus similis. Journal of Nematology 39:99-100.<br /> <br /> Mebrahtu, T., Devine, T.E., Donald, P.A. and Abney, T.S. 2007. Registration of Owens vegetable soybean. Journal of Plant Registrations 1:95-96.<br /> <br /> Melakeberhan, H. 2007. Effect of starter nitrogen on soybeans under Heterodera glycines infestation. Plant and Soil 301:000-000.<br /> <br /> Melakeberhan. H., S. Mennan, M. Ngouajio, and T. Dudek 2007. Effect of Meloidogyne hapla on multi-purpose use of oilseed radish (Raphanus sativus). Nematology 00: In press.<br /> <br /> Melakeberhan, H. 2007. Nutrient use efficiency and precision management of nematodes-Concepts and possibilities. Brazilian Journal of Nematology 00: In press.<br /> <br /> Melakeberhan. H. 2007. Nutrient use efficiency and precision management of nematode-Concepts and possibilities. 27th Congress of the Brazilian Society of Nematologists Program Abstracts. 34.<br /> <br /> Melakeberhan, H., S. Mennan, S. Chen, B. Darby, and T. Dudek 2007. Integrated biological approaches to understanding and managing Meloidogyne hapla populations' parasitic variability. Crop Protection 26:894-902.<br /> <br /> Melakeberhan. H., S. Mennan, M. Ngouajio, and T. Dudek 2007. What form of oil seed radish (Raphanus sativus) is best for managing Meloidogyne hapla? Journal of Nematology 39:73.<br /> <br /> Melakeberhan, H., Xu, A., Kravchenko, A., Mennan, S., and E. Riga. 2006. Potential use of arugula (Eurica sativa L.) as a trap crop for Meloidogyne hapla. Nematology. International J. Fundamental and Applied Nematological Research. 8:793-799.<br /> <br /> Mengistu, A., Kilen, T.C., and Donald, P.A. 2007. Registration of D95-5048 soybean germplasm line resistant to Phytophthora rots and soybean cyst nematode races 3 and 14. Crop Science 47:452.<br /> <br /> Mennan, S., S. Chen, and H. Melakeberhan. 2007. Effects of Hirsutella minnesotensis and N-Viro soil on populations of Meloidogyne hapla. Biocontrol Science and Technology 17:233-246.<br /> <br /> Miyasaka, S.C., J. DeFrank, B.S. Sipes, and A. Blas. 2007. Green manure effects on root-knot nematodes (Meloidogyne javanica) and following taro (Colocasia esculenta) crop. American Society of Agronomy. <br /> <br /> Mojtahedi, H., Brown, C.R., Riga, E., and L.-H Zhang. 2007. A new pathotype of Meloidogyne chitwoodi race 1 from Washington State. Plant Disease. (In Press). <br /> <br /> Norsworthy, J. H., J. Schroeder, S. H. Thomas, and L. W. Murray. 2006. Purple nutsedge (Cyperus rotundus) management in direct-seeded chile peppers (Capsicum annuum) using halosulfuron and cultivation. Weed Technology 21:636-641.<br /> <br /> Ou, Z., L. Murray, S. H. Thomas, J. Schroeder, and J. Libbin. 2007. Nutsedge counts predict Meloidogyne incognita juvenile counts in an integrated management system. Journal of Nematology (in review).<br /> <br /> Poinar, G. O. Jr., S. D. Porter, S. Tang and B. C. Hyman. 2007. Allomermis solenopsii sp. new. (Mermithidae: Nematoda) parasitizing the fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae) in Argentina. Systematic Parasitology 68:115-128.<br /> <br /> Riga, E., Karanastasi E., C.M.G. Oleveira, and R. Neilson. 2007. Molecular identification of two stubby root nematode species. The American J. Pot. Res. 84:161-167. <br /> <br /> Schroeder, J., S. Nunez, S. H. Thomas, and L. W. Murray. 2007. Early season irrigation affects initial development of yellow and purple nutsedge and root-knot nematode. Weed Science Society of American Abstracts 47:69.<br /> <br /> Sipes, B., M.-L. Wang, C. Nagai, J. Hu, K. Cheah, P. Moore, R. Paull, and H. Atkinson. 2007. Reproduction of Meloidogyne javanica on pineapple genetically modified to express a rice cystatin. Phytopathology 97:S108.<br /> <br /> Tang, S. and B. C. Hyman. 2007. Mitochondrial genome haplotype hypervariation within the isopod parasitic nematode Thaumamermis cosgrovei. Genetics 176:1139-1150.<br /> <br /> Trojan, J. M., S. H. Thomas, J. Schroeder, and L. W. Murray. 2006. Host suitability of yellow nutsedge and purple nutsedge for Meloidogyne javanica, M. hapla, and M. incognita races 1,2, and 3. Journal of Nematology 38:299.<br /> <br /> Zasada, I., M. F. Avendano, Li, Y. C., T. Logan, H. Melakeberhan. , S. R. Koanning, G. L. Tylka 2007. Potential of alkaline-stabillized biosolid to manage nematodes: Case studies on soybean cyst and root-knot nematodes. Feature Artcile. Plant Disease 00: In press.<br /> <br />

Impact Statements

1. The magnitude and frequency of mtDNA haplotype variation in mermithid nematodes is unprecedented among metazoan mitochondrial genomes.
2. Molecular phylogeny will help in the identification of mermthid nematodes species and provide a useful platform to select appropriate entomopathogenic nematodes for targeted biological control programs.
3. Crop rotation can control nematode damage and manage genetic variation Heterodera glycines.
4. Suppression of Meloidogyne chitwoodi by green manure crops in long warm growing seasons requires augmentation with other strategies such as non-fumigant nematicides or rotation with poor or non-host crops.
5. Green manure crops provide sufficient suppression of Meloidogyne chitwoodi in short, cool growing regions, for crops intended for domestic sale but should not be used as the sole management strategy for crops intended for seed or export.
6. Cactodera sp. recovered reproducing on corn in Tennessee has a narrow host range with highest reproduction on corn.
7. Heterodera glycines has been identified on the island of Kauai in Hawaii.
8. Globodera rostochiensis was not found in Idaho.
9. Globodera pallid has a limited distribution in Idaho.
10. Ozonation can be an effective method for controlling nematodes in water and may be viable in a commercial setting.
11. Transgenic cystatin anthurium, coffee, and pineapple may offer growers alternatives for the management of root-knot nematodes that is sustainable and environmentally friendly.
12. Animal waste adversely affects reproduction of Heterodera glycines.

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