CARBON SOURCE-DEPENDENT VOLATILE PRODUCTION AND ASD EFFICACY FOR SUPPRESSION OF APPLE ROOT PATHOGENS AND PARASITES

Studies were conducted to determine the effect of carbon source input on efficacy of anaerobic soil disinfestation (ASD) for control of multiple components of the apple replant disease pathogen complex.
Among five C sources tested, ASD conducted using ethanol (ET) or grass residues (GR) effectively suppressed infection of ‘Gala’ seedling roots by Pythium spp.
ASD was effective in suppressing seedling root infestation by Pratylenchus penetrans for all carbon inputs except composted steer manure (CM). GR and ET ASD treatments reduced persistence of Rhizoctonia solani AG 5 in artificially infested soil and all treatments except CM effectively reduced root infection by this pathogen.
Each C amendment generated a unique spectrum of volatiles during the anaerobic phase and those from ET, GR, and Brassica juncea seed meal (SM) treatments effectively retarded colony growth of R. solani AG 5, P. ultimum and Fusarium oxysporum. Among selected volatiles generated during ASD, decanal, allyl isothiocyanate and dimethyl trisulfide effectively retarded growth of all three pathogens whereas the latter two were bioactive against P. penetrans. Among grass residue amendment rates examined, an application rate of 20 t ha^-1 resulted in superior seedling biomass production and lesion nematode suppression, while free-living nematode populations were unchanged relative to no amendment control.
These studies demonstrate the significant potential of ASD for controlling ARD pathogens and parasites when GR is utilized as the C input.

VIII International Symposium on Chemical and Non-Chemical Soil and Substrate Disinfestation

M. Mazzola, S. Hewavitharana

anaerobic soil disinfestation, apple replant disease, antifungal volatiles, nematicidal volatile

https://doi.org/10.17660/ActaHortic.2014.1044.24