Brief Summary of Minutes of Annual Meeting

W-2186: Variability, Adaptation, and Management of Nematodes Impacting Crop Production and Trade 2008 Annual Report NOTE: In order to highlight the challenges associated with finding and dealing with the potato cyst nematode and trade issues that recently have come to light, Oregon's report under Objectives 1 and 4 is presented first and separately. Oregon's Report: Objective 1: Characterize genetic and biological variation in nematodes relevant to crop production and trade. Golden potato cyst nematode (Globodera rostochiensis) was first detected in North America from New York in 1941 and later from Newfoundland in 1962 and British Columbia in 1965. Pale potato cyst nematode (G. pallida) was also reported from Newfoundland in 1968. Then in 2006, G. pallida was discovered in Idaho and G. rostochiensis was reported from Quebec. Samples from potato seed fields in Alberta were found to contain G. rostochiensis in 2007. Guidelines to protect the potato industries in both Canada and the United States from spread of potato cyst nematodes (PCN) were approved by APHIS and CFIA early in 2008. Oregon State University owns a farm in Central Oregon near Powell Butte where seed from all the potato breeders in the Tri-State (ID, OR, WA) Variety Development Program is increased for distribution to other areas for further evaluation. The farm is in an ideal location because it is isolated from other potato production areas, which minimizes the probability of introducing potato pests into early generation potato seed. Potato seed grown on this farm during 2007 was scheduled to be shipped to Canada in 2008 so the field was sampled on April 28, 2008 in accordance with the new U.S.-Canadian guidelines. When the Oregon Department of Agriculture (ODA) processed the samples, six nematode cysts were recovered and sent to the USDA Nematology Laboratory in Beltsville, MD. The cysts were identified as Globodera by morphological and molecular procedures but the species identification was inconclusive. The Oregon Department of Agriculture imposed an Administrative Directive on the farm to prevent any movement of potatoes or soil off the property. More soil was collected and processed on May 15 and an additional 18 cysts were found, eight of which were sent to Beltsville. These cysts were also identified as Globodera but were morphologically and molecularly distinct from criteria used by APHIS to identify G. pallida (pale cyst nematode) or G. rostochiensis (golden nematode) and thus, were not determined to be PCN. Therefore, ODA rescinded the Administrative Directive since no regulatory action was required. Impact Statement: Although the nematode was not identified as G. pallida or G. rostochiensis there is still interest and concern about what it is and how it may impact potato growth. Nothing about its host range and potential pathogenicity is known. While it could potentially be a parasite of native vegetation from the area, possibly reproducing on weeds in agricultural fields, it could also be a pathogen of potato, a new species of PCN. If it were a pathogen of potato, the level of pathogenicity would have to be established to determine if it warrants regulation. If it is not a pathogen of potato it may represent a potentially valuable model organism for studying aspects of biology and management of a nematode that may be biologically similar to PCN without the constrictions of working with a regulated pest species. Objective 4: Implement rapid information transfer of project results to stakeholders. Oregon is a major exporter (4.6 million lb in 2008) of grass seed to Korea. Several shipments of grass seed collectively worth over $200,000 were rejected by the Korean National Plant Quarantine Service (NPQS) due to the presence of nematodes and returned to Oregon. The primary grower/shipper that was impacted requested assistance from the Oregon State University Nematology program on how to manage the grass seed crop so that these rejections would not occur. The nematodes listed were Aphelenchoides haguei, Paraphelenchus acontioides and Subanguina sp. These nematodes were listed on the Korean Harmful Organism List and thus were not inspected for by the Oregon Department of Agriculture when issuing phytosanitary certificates required for export. Inspection of samples from grass seed that returned from Korea by an OSU nematologist detected Aphelenchoides and Paraphelenchus, but not Subanguina. Since the species of Subanguina was not determined by NPQS and since Subanguina was not recovered from samples returned to Oregon the relative risk associated with the inceptions of Subanguina by NPQS could not be determined. Some species are pathogenic but little is known about other species. However, detections of Subanguina by NPQS were only in red fescue and blends containing red fescue. The red fescue included in these shipments had been obtained from a source from outside of Oregon for the purpose of making these blends. The grower was advised to find a different supplier of red fescue for blending with his seed. Research of the literature on A. haguei and P. acontioides revealed that both nematodes fed on fungi and that neither was reported as a plant pathogen. Therefore, neither species presented any risk to Korean agriculture. A letter documenting the biology and degree of risk from A. haguei, P. acontioides and Subanguina sp. was sent to APHIS where it was forwarded onto NPQS. Subsequently, NPQS replied to APHIS that A. haguei, and P. acontioides would no longer be regulated at the port of entry. However, ruling on the risk assessment of Subanguina was delayed until the species could be determined. Both APHIS and NPQS were very helpful and accommodating in resolving this issue. Impact statement: Rejections of Oregon grass seed exported to Korea due to inceptions of nematodes associated with the seed were resolved when it was determined that the nematodes in questions did not pose a risk of plant disease to Korean Agriculture. Annual value of the contract of the impacted stakeholders alone was $2 million. Had these nematodes been found in seed from other farms in Oregon, exports of $5 million (2007) could have been in jeopardy. All States' Report: Objective 1: Characterize genetic and biological variation in nematodes relevant to crop production and trade. Root-knot nematode (Meloidogyne spp.) interactions with resistance genes in the host crops cowpea (Vigna unguiculata), lima bean (Phaseolus lunatus), and cotton (Gossypium spp.) were examined to determine specificity of nematode responses to different resistance genes in these crop plants in CA. These studies are coupled with efforts to breed new varieties with improved nematode resistance. New resistance sources have been identified in each of these crop species that confer unique specificities that match avirulence genes in the nematode. An analysis of the resistance inheritance in Lima bean Cariblanco N and its donor L-136 was completed. In crosses between the resistant parent and susceptible Henderson Bush, a series of three independent resistance genes was determined to control resistance. One gene was found to confer root galling resistance to M. incognita, a second gene conferred resistance to M. incognita reproduction, and a third gene conferred resistance to M. javanica root galling. Tests with recombinant inbred lines from the cross confirmed that each gene acted alone, and that a combination of all three genes was necessary to provide comprehensive nematode resistance. The independence of galling and reproduction resistance traits provides an excellent model system for dissecting molecular pathways governing these important plantnematode interactions. In cowpea, additional field isolates of both M. incognita and M. javanica were found in California cowpea fields that were virulent to gene Rk. In cotton, genetic analysis, molecular mapping, and marker development revealed a major M. incognita resistance gene, rkn1, on chromosome 11 in the upland cotton (Gossypium hirsutum) Acala NemX. In progenies derived from crosses between Acala Nemx and the root-knot susceptible G. barbadense cultivar Pima S7, a significant number of individual plants were found with extremely high levels of resistance. These transgressive segregants were much more resistant than the resistant parent of the cross. Genetic and molecular marker analysis using BAC-end derived and other SSR markers revealed a gene in Pima S7, named RKN2, that when combined with rkn1 from Nemx, resulted in the ultra-resistant phenotype. Genetic mapping of the markers revealed that gene RKN2 is also located on cotton chromosome 11, in the same region as rkn1. The novel resistance based on these clustered genes has important potential for improving nematode management in cotton. The SSR markers tightly linked to each gene were confirmed to be effective for indirect screening of the high resistance in a marker-assisted selection approach to cotton breeding. The RKN2 gene markers were used to screen cottons with different genome origins, and indicated that RKN2 originated from the A2 cotton genome. In Hawaii, evaluation of semi-wild Ethiopian (ET) coffee (Coffea arabica) for resistance to the root-knot nematode, M. konaensis, showed that ET25B and ET15 grew well in the presence of nematodes and may be of use in the coffee breeding program. Evaluation of taro (Colocasia esculenta) germplasm for resistance and tolerance to M. javanica found differences that while statistically different would not provide sufficient levels of control. In Idaho, screening of onion cultivars to P. penetrans indicated that Caveat, Vision, R10 Tinto, and Mercury were resistant to P. penetrans. 'Caveat' was considered to have the best resistance to P. penetrans which would be useful for nematode management. Cultivars susceptible to P. penetrans included Sanfan and Sweet Sunrise. An experiment was conducted under green house conditions to evaluate the tolerance level of ten alfalfa genotypes to the Columbia rot knot nematode M. chitwoodi. In the variety Ts 5011 there was a significant increase in the fresh and dry weight of shoot and root followed by the lowest level of M. chitwoodi population in the root. Screening of sugar beet accessions to sugar beet cyst nematode indicated that the lowest number of cysts on the root was observed in the sugar beet accession PI 540574. To determine whether PI 88788 resistance was changing or whether soybean cyst nematode (Heterodera glycines) was adapting to this source of plant resistance was investigated in TN as part of a regional peoject. This source of resistance is present in approximately 97% of commercial seed. Tennessee represented the state which had deployed plant resistance to soybean cyst for over 30 years. Soil samples were collected throughout the state and egg population density was increased until there were sufficient eggs to characterize the population. More than 4,000 soil samples were collected but only 40 had sufficient population density to characterize. No HG Type 0 was detected and all populations were able to reproduce on PI 88788. In Hawaii, a new infestation of the soybean cyst nematode on Kauai, and a population of M. javanica that has proven to be devastating on grapefruit (Citrus × paradisi) but limited in geographic area, were discovered. In MI, analysis of three, from mineral soils, and one from muck soil, populations of M. hapla on seven carrot cultivars adapted to the Great Lakes Region and 'Rutgers' tomato (susceptible control) was investigated. While varying in their degree of susceptibility, all carrot cultivars were equal to or more susceptible than tomato. Across nematodes and experiments, the population from muck soil infected the least and a population from sandy soil infected the most. The results support the hypothesis that soil-driven conditions may influence parasitic variability of M. hapla populations. In collaboration with principle investigators from University of Florida and co-investigators from the University of New Hampshire, researchers at the University of Nebraska, Lincoln, have been examining the application of metagenomic soil analyses for the assessment of nematode community species composition. Their focus has been on the suitability of different primer sets to best represent DNA diversity from nematodes extracted and collectively homogenized for PCR amplification. Comparisons between metagenomic estimates of diversity and estimates derived from a sequential analysis of individual nematodes indicate that the metagenomic approach recovers virtually all the diversity found in the sequential analysis. Such approaches will be helpful as integrating nematode community structure into various aspects of nematode management strategies increase (see Objective 3). Objective 2: Determine nematode adaptation processes to hosts, agro-ecosystems and environments. In NM, populations of yellow nutsedge (Cyperus esculentus) were collected from different geographic regions of North America, including areas outside the geographic range of M. incognita, and are being propagated in the greenhouse. Studies are planned to determine if interactions that have been observed in the southwestern USA, such as host suitability for nematode reproduction or proliferation of nutsedge tuber production following nematode infection, represent local co-adaptation of the nematode and weed, or are inherent within yellow nutsedge. In 2007, areas of high M. incognita infestation were identified in heavy-textured, clay loam soils in chile pepper fields in Doña Ana and Luna counties that are poorly suited to the nematode. Chile infection appeared to be limited to areas with high incidence of annual weeds that were also infected by M. incognita and Verticillium dahlia. We hypothesize that pockets of difficult-to-control annual weeds may act as host reservoirs for the nematode under these conditions. In 2008 a greenhouse experiment was conducted to determine the host suitability of chile pepper, spurred anoda (Anoda cristata), tall morningglory (Ipomea purpurea), and Wrights groundcherry (Physalis wrightii) to M. incognita and V. dahlia. Data are still being collected, after which statistical analysis will test the following questions relative to the plant responses: 1) what is the response of each plant species to the nematode and fungal pathogen (alone and in combination)? 2) What is the relative sensitivity of the four plant species to the nematode, fungus, and the combination (data will be expressed as a % of the uninoculated control for this analysis)? In 2008 additional chile pepper fields in southeastern NM were found to be infested with M. hapla. Past surveys comprised of 10% each of the cotton, chile, and alfalfa hectarages revealed primarily M. incognita in this region. Future work is planned to determine the frequency of single versus mixed-species root-knot populations throughout the region and to identify factors that may be contributing to proliferation of M. hapla. In TN, over 300 soil samples were examined for the presence of the goose grass cyst nematode found parasitizing corn in 2006. The nematode can consistently be recovered from the field site detected in 2006 and several other field sites continue to test positive in greenhouse bioassays. The exact location of the original find in 1978 is still not known. Host studies indicate that only goosegrass, corn and close relatives are hosts. No field crops typical of the Midwest are hosts nor are common cyst nematode hosts such as potato, tobacco, or soybean. In Idaho, pathogenicity studies of Pratylenchus penetrans on onion indicated that this nematode caused significant plant growth reduction at the lowest inoculum level of two nematodes/ cm3 soil. Yield loss of onion increased significantly at all inoculum level. The same quadratic decrease and increase trend in plant and nematode parameters were observed in onions inoculated with the root knot nematode M, hapla. Significant plant growth reduction by M. hapla started at the density of two J2/ cm3 soil. Bulb weight was reduced by 17.5% to 41.3% with the increasing inoculum levels in field microplots. More damage was caused by P. penetrans than M. hapla when the two species were inoculated at the same density. There was a competition between P. penetrans and M. hapla on onion. Significantly more damage in onion was observed when the two species were inoculated simultaneously at a 1:1 ratio rather than either species alone. P. penetrans and M. hapla suppressed each other for multiplication on onion. Nematode population in roots and the final total population at harvest were reduced for both species when they existed together in soil, but the suppressive effect of P. penetrans on M. hapla was more severe than that of M. hapla on P. penetrans. In MI, exploiting the multi-purpose traits of brassicas was investigated by testing the effects of 0 (check), 4,000 or 8,000 NRKN eggs/300 cm3 of either sandy, sandy loam, or muck soil on arugula's (Eruca sativa L., cv 'Roquette') ability to trap an M. hapla population and if nematode infection affects biomass accumulation and vegetative (nutritional) quality. Roquette was selected to meet organic production requirements. Similar numbers of nematodes were recovered from the high and low nematode treatments in the three soil types and nematode infection had no effect on plant growth or nutritional quality of arugula. However, arugula's growth and leaf nutritional quantity were significantly affected by soil type. In addition to providing basis for entrepreneurial opportunities to test arugula's trap, vegetable, and possibly biofumigant attributes from one seeding, the results support the hypothesis that arugula can trap M. hapla in different soil types without affecting its vegetative growth and quality. Objective 3: Develop and assess nematode management strategies in agricultural production systems. Developing and integrating ecologically friendly nematode management alternatives has been as complex as the croppings systems diversity. The Columbia root-knot nematode, M. chitwoodi is the most important root-knot nematode pathogen of potato, Solanum tuberosum, followed by the root-lesion nematode, Pratylenchus penetrans, and the stubby root nematode, Paratrichodorus allius. In addition, the Potato Cyst nematode (PCN), Globodera pallida, found in Idaho in 2006, is a new threat to the WA potato industry. Furthermore, G. rostochiensis, a close relative to G. pallida has been found in Alberta, Canada, potato seed source for WA growers for several years. In order to deal with current and potentially emerging nematode problems, a variety of management options are being employed in vegetable and field crops. The use of organism-derived biofumigants like Muscodor albus, fungal endophyte, have been shown to be effective against multiple nematode species in tomato, pepper, bean and potatoes. Plant-derived biofumugants like brassicas show promising effects on plant-parasites without adversely affecting beneficial nematodes. As part of wPCN eradication plan, greenhouse assay using green manure is in progress. In Hawaii, growers have observed green manure crops growing in the field and are able to make better informed management decisions. In Idaho, a micro plot study using the new product (DMDS) on tomato at different rates for control of Columbia root-knot nematode indicated that all treatments significantly reduced the nematode population in comparison to the untreated control. A field experiment to study the efficacy of biopesticide at different rates for control of Columbia root-knot nematode in a potato field indicated that the percent of tubers with nematode infection in treated plots ranged from 31.5 to 97.8. Lowest level of nematode infection was recorded in the plots treated with Temik + Vydate treatment followed by the highest rates of WD and Chancellor treatments. Another field experiment with DMDS (ten treatments) indicated that nematode infected tubers as well as percent of nematode infection were significantly reduced by the treatments compared to control plots. Percent of tubers with nematode infection in DMDS treated plots ranged from 0.2 to 25.6. In WA, a comparison of naturally derived biofumigants and synthetic fumigants (double bio/synthetic fumigation) can protect potato tubers against M. chitwoodi. In order to manage foliar pest like Colorado potato beetle (Leptinotarsa decemlineata) and root-knot nematodes, augmentation and conservation of insect-attacking nematodes and fungi were tested in potatoes. Biofumigation interfered with augmented biocontrol in the soil and reduced some species of non-target organisms. A notable component of dealing with nematode-virus interactions in WA potato production has been the development of rapid detection of viruliferous nematodes, which, in return, allows growers to make judicious decisions on stubby root nematode control and appropriate farming practices. Integrating nematode community structure into agricultural nematode management is continuing in several fronts. In NM, data pertaining to nematode community structure (NCS), indicator of soil biological and agro-ecological changes, have been collected from soil samples from all surveys and nematode management experiments since 2006. At the request of local producers who are concerned about long-term irrigation commitments associated with 3-year alfalfa rotations used for suppression of the M. incognita/yellow nutsedge/purple nutsedge pest complex, experiments will be initiated in spring 2009 to evaluate the effectiveness of annual cover and rotation crops toward these ends. In TN, studies are continuing on effect of tillage on soybean cyst nematode reproduction and also on the effect of poultry litter on soybean cyst nematode reproduction. In both studies data are being collected on soil community analysis and normalized difference vegetative index (NDVI, physiological indicator of plant health) in addition to egg population density and yield. The objective is to explain the differences in reproduction seen with the different treatments. Among other things, accounting for and explaining agro-ecological health and complexities, for which NCS is an excellent indicator, are critical when imposing nematode parasitic variability management strategies. Expanding on the fertilizer use efficiency (FUE) model (which separates nutrient deficiency and toxicity from nematode parasitism as well as suitability of treatments designed to achieve desired biological and physio-chemical soil health conditions) and incorporating NCS, the MI group has developed cross-disciplinary models for testing soil amendment-driven management of biotic and abiotic factors. Objective 4: Implement rapid information transfer of project results to stakeholders. In addition to the list of four categories of publications, following are venues and avenues where research results were delivered to stakeholders: OR: - Update on cyst nematodes in potato. Hermiston Agriculture Research and Extension Center Potato Field Day. June, 2008. - Timing of in-season soil sampling for Columbia root-knot nematode. Hermiston Agriculture Research and Extension Center Potato Field Day. June, 2008. - Nematode management with crop rotation: Impact of biofuel crops. 34th Annual Hermiston Farm Fair and Trade Show, Hermiston, OR. November, 2007. NM: - The NM Vine and Wine Society (29 Feb - 1 March 2008). - The NM Chile Association advisory board (10 June 2008). - The NM Chile Association Chile Field Day (19 August 2008). - NM Certified Applicator Continuing Education Training (9 October 2008). HI: - Reports, letters, phone conversations, and theses. - Field days were held on several occasions to interact with taro growers. TN: - Soybean plant reaction to soybean cyst nematode for commercially available cultivars is published in the following websites. http://www.utextension.utk.edu/fieldCrops/soybean/diseases/disease_images/2007-Soybean-Report.pdf and http://www.utextension.utk.edu/fieldCrops/soybean/soybean_images/Soybean%20Variety%20Performance%20Tests%20in%20Tennessee%202007%20-%20for%20Web%20Posts.pdf WA: - Nematology Extension: http://www.prosser.wsUniversityedu/faculty/riga/Riga-index.html