Influence of rootstock genotype on efficacy of anaerobic soil disinfestation for control of apple nursery replant disease
2020
Hewavitharana, Shashika S. | Mazzola, Mark
Apple replant disease (ARD) in production nurseries can negatively impact commercial viability by diminishing tree quality and potentially serving as a source of pathogen inoculum. The current study was carried out to determine the potential for plant genotype to influence anaerobic soil disinfestation (ASD) disease control efficacy. M.9, G.41, and G.935 apple rootstock genotypes were employed. ASD was conducted using orchard grass as the carbon input (10 t ha⁻¹ or 20 t ha ⁻¹). Rootstock growth in ASD-treated soils was comparable to that attained in response to soil pasteurization or fumigation with 1,3-dichloropropene/chloropicrin (FUM) in both greenhouse (GT) and nursery field trials (NFT). In GT, Rhizoctonia solani AG-5 root infection and growth performance varied with rootstock genotype and soil treatment. ASD reduced pathogen DNA quantity in roots and improved rootstock growth. Genotype, but not soil treatment, influenced root infestation by Pythium ultimum and R. solani in the NFT. ASD with grass input at 20 t ha ⁻¹ improved soil nutrient levels, especially NO₃⁻ N, and provided significant weed control in the NFT. Treatments significantly altered composition of the bulk soil and rhizosphere microbiome in GT and these effects were prolonged in ASD-treated soils. In NFT, ASD conducted with orchard grass was uniformly as effective as FUM in the control of ARD and increase in trunk diameter increment, the primary determinant of apple rootstock value. This ASD treatment can be suggested as a potential method for effective control of nursery replant disease across rootstock genotypes varying in disease tolerance.
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