Submitted to: International Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/7/2011
Publication Date: 12/1/2011
Citation: Meyer, S.L.F., Orisajo, S.B., Chitwood, D.J., Vinyard, B.T., Millner, P.D. 2011. Poultry litter compost for suppression of root-knot nematode on cacao plants. International Journal of Nematology. 21(2):153-162. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack crop plants and cause an annual worldwide crop loss in excess of 100 billion dollars. To enhance successful production of cocoa beans, growers need safe, affordable strategies for managing root-knot nematodes, which are economically the most important nematodes that infect cocoa seedling roots. Chicken litter is readily available in many cocoa-growing areas, so chicken litter compost amended into soil was studied for effects on nematode population numbers and on plant vigor. Liquid extracted from the compost inhibited nematode eggs from hatching and suppressed activity of hatched nematodes. In greenhouse studies with cocoa seedlings in pots, some rates of compost amendment increased the vigor of cocoa seedlings and decreased numbers of nematode eggs in each pot. The results are significant because they indicate that there is potential for poultry litter compost to be applied by growers as a sustainable amendment for improving health of cocoa seedlings. Consequently, this research will be used by researchers and agronomists interested in developing safe methods for minimizing crop losses caused by nematodes in cocoa plantings.
Technical Abstract: Root-knot nematodes (Meloidogyne spp.; RKN) are economically the most important nematodes that attack cacao (Theobroma cacao L.) plants worldwide. Poultry litter (poultry manure mixed with the wood shavings that are used for bedding or for covering the soil floor in poultry housing units) compost was investigated as an amendment for suppressing populations of Meloidogyne incognita and increasing plant vigor. The studies were conducted with mature compost produced in a static aerated pile. Compost extract was prepared by steeping 100 g compost in 100 ml tap water and removing biomass with cheesecloth filtration followed by centrifugation. The supernatant was diluted 1:4 in water and sterile filtered and used as a 100% compost extract treatment. In microwell assays, M. incognita egg hatch and J2 activity were inhibited by all tested compost extract concentrations (25%, 50%, 75% and 100% extract), with > 90% inhibition in 100% compost extract after 3 and 7 day incubation periods. In greenhouse tests, cacao ‘Pound 7’ seedlings were transplanted into soil amended with compost. The five treatments were: 1) No poultry litter compost, no RKN; 2) No poultry litter compost, +RKN (5,000 eggs per pot); 3) 2.5% poultry litter compost (by volume), +RKN; 4) 4.5% poultry litter compost, +RKN; 5) 10.0% poultry litter compost, +RKN. Treatments (including nematodes) were placed into pots two weeks prior to seedling transplant. At harvest, stem height, stem fresh weight, and leaf fresh and dry weights were significantly greater with 5% and/or 10% compost amendment than with no compost. Stem girth in all compost treatments was greater than in controls without M. incognita. Compost treatments significantly decreased numbers of nematode eggs collected from pots at harvest; egg populations were suppressed by 34.9%, 50.6% and 72.5% in the 2.5%, 5.0% and 10.0% compost treatments, respectively. The results indicate that poultry litter compost amendments have potential for suppressing M. incognita populations on cacao seedlings and improving plant vigor.