Ecologically-based nematode management : exploiting nematode survival strategies for developing novel cover cropping and soil solarization practices

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2011-08
Authors
Marahatta, Sharadchandra Parasar
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[Honolulu] : [University of Hawaii at Manoa], [August 2011]
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Abstract
Improving the use of cover crops, such as Crotalaria juncea and Tagates patula, is needed for management of plant-parasitic and free-living nematodes. These cover crops might improve soil health conditions through a strip-till cover cropping practice. The integration of cover cropping of C. juncea and soil solarization could further improve ecological-based nematode management more than C. juncea alone. Additional improvement could be achieved if T. patula or C. juncea are found to suppress Meloidogyne incognita or Rotylenchulus reniformis more efficiently when these nematodes are in a vulnerable state. Strip-till cover cropping (STCC) of C. juncea suppressed M. incognita, but T. patula only suppressed M. incognita when planted immediately following after a susceptible host. In addition, STCC of C. juncea also enhanced population densities of bacterivorous and fungivorous nematodes, whereas STCC of T. patula enhanced these free-living nematodes inconsistently. Integration of C. juncea cover cropping and soil solarization did not reduce R. reniformis opulation densities, but reduced weed coverage as compared to C. juncea alone. The benefits of integrating C. juncea to soil solarization were only observed where C. juncea biomass was high (3.6 Mt/ha). Leachate of T. patula did not suppress egg hatch and J2 activity of M. incognita. However, planting of T. patula in a greenhouse pot experiment suppressed M. incognita J2 activity if the soil was conditioned with irrigation or cucumber leachate but not with dry treatment. On the other hand, planting of C. juncea and cowpea (Vigna unguiculata) reduced the number of R. reniformis in anhydrobiotic state. Amending soil with C. juncea suppressed R. reniformis more efficiently if fewer anhydrobiotic R. reniformis were present. In conclusion, C. juncea outperformed T. patula in a STCC system, whereas integration of C. juncea with soil solarization did not improve the benefit of a cover crop, C. juncea. Based on the greenhouse studies, the nematode suppressive effect of T. patula could be improved by planting T. patula immediately after a susceptible host. Benefits of C. juncea amendment were more obvious if used immediately after nematode susceptible (poor or good) hosts.
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Ph.D. University of Hawaii at Manoa 2011.
Includes bibliographical references.
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nematodes
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Theses for the degree of Doctor of Philosophy (University of Hawaii at Manoa). Tropical Plant Pathology.
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