Present - Edward McGawley-LA, Kathy McLean-AL, Gary Lawrence-MS, J. L. Starr-TX, S.-Y. Chen-MN, Steve Lewis-SC, Greg Noel-USDA-IL, Patricia Timper-USDA-GA, Jon Eisenback-VA, Robert Riggs-AR, Robert Robbins-AR, Charles Johnson-VA, Richard Hussey-GA, Eric Davis-NC, Don Dickson-FL, Fred Knapp-Admn. Adv.
TITLE: Managing Plant-parasitic Nematodes in Sustainable Agriculture with Emphasis on Crop Resistance.
Objective 1. Identify and characterize new sources of resistance genes in cotton, selected vegetables, peanut, and soybean to plant- parasitic nematodes.
(AR) Soybean cultivars and breeding lines in Maturity Groups (MG) III-VII were tested against one or more of races 1-8 of Heterodera glycines, and/or Rotylenchulus reniformis,and/or Meloidogyne incognita, M. arenaria, and M. javanica. Few were resistant to any race of H. glycines other than races 1, 3, and 14 (AR, GA, KY, NC); many of those resistant to H. glycines were resistant to R. reniformis (AR, NC); and 8,931, 5,750, and 639 respectively, were resistant to Meloidogyne incognita, M. arenaria, and M. javanica, respectively (GA). More new cultivars were resistant to SCN races 3 and/or 14, than previously and some also had resistance to 2-3 Meloidogyne spp. and some cv's in MG VI, VII, and VIII and several GA breeding lines were resistant to damage by Columbia lance nematode. Surveys revealed that M. hapla was present in more than 50% of soybean fields in VA (VA). Cv's resistant to M. incognita, M. arenaria, and M. javanica are usually susceptible to M. hapla but 1 breeding line was resistant to race A (VA). Of sweet potato cv's tested for resistance to M. incognita, M. arenaria, and M. javanica, Beauregard was highly resistant (NC). Tests of cotton cv's revealed that 3 were resistant to M. incognita (NC) and 1 was resistant (NC) several were tolerant to R. reniformis (LA). Resistance to M. incognita in most Capsicum annuum cv's was reduced at 28 and 32oC, but some cv's exhibited only a partial loss of resistance (USDA-SC).
Objective 2. Facilitate the development of nematode resistant cultivars in these crops.
Among soybean crosses, 446 had gall ratings < 2, 254 had ratings < 1 in tests for resistance to M. incognita (AR). Of 12 mid-south cotton cv's tested all were susceptible to M. incognita and R. reniformis but Rf values for the former were 5.4-42.9 and to the latter were 17.9-63.7 (MS). Yields from 19 soybean cultivars in R. reniformis-infested soil were 61.9-71.3 bu/A, 46.9-56.7 bu/A, and 39.6-49.6 bu/A, respectively on MG IV, V, and cv's and was affected by Temik nematicide only in MG VI cv's (MS). 'Musen', MG VI, and 'Motte', MG VII, soybean cv's resistant to SCN races 3 and 14, and the latter resistant to M. incognita and R. reniformis and tolerant to Columbia lance nematode, were released (SC). Of 11,000 soil samples analyzed 56% contained R. reniformis (LA). Variation among 5 populations nematode from 5 states on 'Stoneville LA887' cotton resulted in large variations in soil J2 population levels, eggs/gm roots, dry root and top wt/plant, and bolls/plant (LA). RFLP markers linked to a single gene for resistance to M. arenaria in peanut were used to select individuals homozygous for resistance from segregating populations of advanced genera on breeding lines (TX). Inheritance of resistance to M. incognita in three cotton genotypes was conditioned by few genes (TX). One breeding line, M240 derived from Auburn 623, has two genes for resistance, whereas resistance in Acala NemX and Stoneville LA887 appears to be conditioned by a single recessive gene (TX). The mechanism of resistance in six genotypes examined resulted in fewer infective-stage juveniles establishing feeding sites within roots of resistant than in the roots of susceptible plants (USDA-GA). Peanut germplasm was identified with resistance to both the M. arenaria and the tomato spotted wilt virus (USDA-GA). Breeding clones of sweetpotato were evaluated for resistance to M. incognita race 3 and 2 entries had resistance similar to Sumor, 3 entries had resistance similar to Nemagold and Tinian (USDA-SC). Seven elite sweetpotato breeding clones had resistance to M. incognita; 6 were highly resistant and 1 was resistant; 1 was susceptible (USDA-SC).
Objective 3. Integrate resistant cultivars and other biotactics into sustainable cropping systems, ensuring the durability of resistance.
In microplots that had the fungus ARF18 added to the soil in 1997 and 1998 but not in 1999, total SCN eggs + J2 at harvest were 1:3:5 in plots treated with ARF-TN, ARF-BG, and Check, respectively (AR). Pasteuria penetrans activity in M. arenaria race 1-infested soil and planted to peanut, okra, soybean, eggplant, and field and sweet corn, had the most endospores in peanut and okra, lowest in chloropicrin-treated plots (FL). Survival of P. penetrans was tested in an M. arenaria race 1-infested field was less following Bahiagrass than following weed fallow (FL). Fungi were isolated from 3.4% of 4,500 SCN females and 1.1% of 25,500 eggs from 45 fields in 26, counties (MN). Fifty percent of 4,500 cysts were colonized by fungi in 62 species (MN). Several fungi parasitized SCN eggs, and Hirsutella rhossiliensis parasitized SCN J2 (as high as 60%) in 43% of fields and H. minnesotensis in 14%(MN). Of 93 isolates of H. rhossiliensis most were very efficient parasites of SCN J2 with a high correlation between parasitism in agar and in pasteurized soil, and with level of fungus used, time of application, and relative nematode density in the soil, plus different levels of cv resistance to SCN (MN). In field trials with SCN race 2 or 4, Hartwig had low SCN levels and the highest yields (NC). Hutcheson yielded well after 2 yrs of corn or 1 yr corn, 1 yr Hartwig soybean (NC). Hartwig and Hutcheson had low yield when planted continuously (NC). The first peanut cultivar (Coan) with resistance to M. arenaria was released by the (TX). Its yield is unaffected by initial nematode population densities up to 100 eggs and J2/500 cm3 soil (TX). P. penetrans is a common bacterial parasite of Meloidogyne spp. AL, FL, and GA, but crop rotation affected spore density (USDA- GA). Densities were high in plots continuously planted to peanut, moderate in the peanut/bahiagrass rotations, and low in the peanut/corn and peanut/cotton rotations (USDA-GA). Density of Pasteuria spores in the soil was related to the amount of nematode suppression (USDA-GA). Soil collected from the peanut/bahiagrass plots (moderate spore densities) suppressed nematode reproduction by 76% compared to soil without Pasteuria (USDA-GA). The results suggest that crop rotation can be used to manipulate the density of Pasteuria in fields where it occurs (USDA-GA). Of 33 corn hybrids commonly grown in Georgia, four supported significantly lower nematode reproduction than the others (USDA-GA).
Significance: Results of these studies will provide better cultivar selections for growers and brings the possibility of biological control on nematodes closer to reality.
Work planned for next year: Because new breeding material is being released each year, all Objectives 1 and 2 projects will continue. Biological control projects will progress to microplot or field applications to make the tests closer to commercial use.
Date ______________________.
____________________________ ____________________________
Robert D. Riggs, Chair Fred Knapp, Administrative Adviser
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Sotomeyer, D., L. H. Allen, Jr., Z. Chen, D. W. Dickson and T. Hewlett. 2000. Anaerobic soil management practices and solarization for nematode control in Florida. Nematropica (in press).
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E. I. Jonathan, K. R. Barker, F. F. Abd-El-Aleem, T. C. Vrain and D. W. Dickson. 1999. Potential of selected bacteria as bio-controls of Meloidogyne incognita on tomato and banana. Journal of Nematology in press (Abstr.).
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Hewlett, T. E. and D. W. Dickson. 1999. Dynamics of Pasteuria penetrans on Meloidogyne arenaria in the field. Journal of Nematology (in press) (Abstr.).
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Giblin-Davis, R. M., B. J. Center, T. E. Hewlett and D. W. Dickson. 1998. Pasteuria-infested soil suppresses Belonolaimus longicaudatus in a bermudagrass green. Journal of Nematology 30:497 (Abstr.).
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Han, H.-R., D. W. Dickson and D. P. Weingartner. 1998. Morphological and biological characterization of Belonolaimus longicaudatus. Journal of Nematology 30:498 (Abstr.).
Riegel, C., D. W. Dickson, L.-T. Ou and L. G. Peterson. 1998. Management of root-knot nematodes in soil enhanced for degrading 1,3- dichloropropene. Journal of Nematology 30:512 (Abstr.).
Riegel, C., D. W. Dickson, K. B. Nguyen and G. C. Smart, Jr. 1998. Management of root-knot nematodes with entomopathogenic nematodes. Journal of Nematology 30:512-513 (Abstr.).
Chen, Z. X. and D. W. Dickson. 1998. Cytology and sporogenesis of Pasteuria penetrans. Journal of Nematology 30:491 (Abstr.).
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Giblin-Davis, R. M., B. J. Center, T. E. Hewlett and D. W. Dickson. 1998. Pasteuria-infested soil suppresses Belonolaimus longicaudatus in a bermudagrass green. Journal of Nematology 30:497 (Abstr.).
Hewlett, T. E., A. C. Schuerger and D. W. Dickson. 1998. Development of a soil suppressive to Meloidogyne arenaria with Pasteuria penetrans. Journal of Nematology 30:499 (Abstr.).
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Han, Hye-rim, D. W. Dickson and D. P. Weingartner. 1998. Morphological and molecular biological comparisons of Belonolaimus longicaudatus isolates cultured in vitro on corn roots. Proceeding of the Florida Soil and Crop Science Society (Abstr.).
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Meyers, D., S. Want, Y. Yan, T. Baum, G. Smant, R. Hussey and E. L. Davis. 1999. Secretion of cellulase into plant tissue by Heterodera glycines. J. Nematol. 31: (in press) (Abstr.).
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