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Evaluating the Potential of Oyster Mushroom Compost Waste for Nematode Management

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Item Summary

Title: Evaluating the Potential of Oyster Mushroom Compost Waste for Nematode Management
Authors: Ching, Shelby
Issue Date: Dec 2015
Publisher: [Honolulu] : [University of Hawaii at Manoa], [December 2015]
Abstract: Several Pleurotus spp. have been documented to release allelopathic compounds against nematodes in laboratory trials. Introduction of this fungus to a crop production field for nematode management are challenged by various environmental factors. Two approaches were proposed to introduce spent oyster mushroom compost waste to a basil
(Ocimum basilicum) agroecosystem: 1) amending transplant media mix with spent mushroom compost substrate, and or 2) delivering the mycotoxin through drenching plant roots with mushroom compost water extract (MCWE). Specific objectives of this thesis include 1) determining amendment rates of Pleurotus sp. compost into potting media to suppress root-knot nematodes (Meloidogyne incognita), 2) determine concentrations of
mushroom compost water extract for nematode suppression, and 3) evaluate a spent oyster mushroom compost based technology for pre- and post-plant nematode management in field trials. A greenhouse pot trial demonstrated that amending spent Pleurotus ostreatus compost with coffee grounds as the substrate, did not suppress population densities of Meloidogyne incognita on basil planted in a sand: soil mix. Four laboratory trials were conducted using spent oyster mushroom compost amended into media with high organic matters in Cone-tainers: yard waste compost was used in Conetainer I, II, and III. And peat: moss: perlite was used in Cone-tainer IV. Numbers of M. incognita were suppressed at mushroom compost amendment rate ≥1% in a yard waste compost media. When amended into peat moss potting mix, mushroom compost amendment also suppressed M. incognita penetration at 1 and 33%. When preparing mushroom compost into MCWE, a minimum of 1% concentration is needed to suppress mobility of M. incognita if incubated for ≥2 days. However, the nematode suppressive effect of MCWE was nematostatic instead of nematicidal. When M. incognita J2s were incubated for 7 days in MCWE Trial II, MCWE suppressed 22 and 41% of viability of M. incognita at as low as 10 and 25% concentration, respectively. Application of oyster mushroom compost was then evaluated in two field trials at Poamoho (Trial I) and Magoon (Trial II), respectively. Although mushroom compost amendment did not suppress plant-parasitic nematodes in both trials, its effects on soil health varied by trial. In Trial I, mushroom compost (amendment or drenching) plots were dominated by bacterial decomposition (lower CI, P < 0.01) initially, and resulted in a reduced soil food web structure (lower SI, P < 0.05). Lack of enhancement of fungivorous nematodes in this trial indicated a poor mushroom mycelia establishment in this field. However, in Trial II, mushroom compost amendment enhanced fungal decomposition as indicated by higher abundance of fungivorous nematodes than no mushroom compost treatments (P < 0.05) throughout the basil crop. The enhancement of fungivorous nematodes throughout Trial II coincided with enhancement of soil health conditions as indicated by an increase in abundance of
bacterivorous (P < 0.05) and omnivorous (P < 0.01) nematodes compared to no mushroom
treatments. When used as a seedling potting mix amendment, nematode richness in amendment plots was also increased (P < 0.05) compared to no amendment. However, spent oyster mushroom compost did not improve basil yield due to heavy infestation of Peronospora belbahrii, but amendment improved height in Poamoho. Spent oyster mushroom compost as amendment and sometimes as drench increased bacterivorous and fungivorous nematodes, and if practiced in area with higher humidity, it could also potentially increase omnivorous and predatory nematodes. In conclusion, although mushroom compost amendment and drench did not suppress plant-parasitic nematodes, they had varying effects in improving soil health. Spent oyster mushroom compost as amendment and sometimes as drench increased bacterivorous and fungivorous nematodes, and if practiced in area with higher humidity, it could also potentially increase omnivorous and predatory nematodes. Overall, the benefits of oyster mushroom compost for suppression of plant-parasitic nematodes and improving soil health might take time. Continual practice of introducing mushroom compost waste in an agroecosystem might be needed to observe the benefits of this saprophytic fungus. Future research is needed to evaluate more frequent MCWE drenching for the management of plant-parasitic nematodes.
Description: M.S. University of Hawaii at Manoa 2015.
Includes bibliographical references.
URI/DOI: http://hdl.handle.net/10125/51159
Appears in Collections:M.S. - Tropical Plant Pathology


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