DISPERSAL OF INOCULUM OF PHIALOPHORA-MALORUM IN PEAR ORCHARDS AND INOCULUM REDISTRIBUTION IN PEAR IMMERSION TANKS

Phialophora malorum was recovered from orchard air during fruit harvest and from surfaces of harvested fruit in orchard bins but not from orchard air or fruit surfaces during the growing season. Propagules of P. malorum were recovered from immersion dump tank solutions in a commercial packinghouse but not from packinghouse air. Redistribution of inoculum from infested to previously uninfested fruit was demonstrated in a research-scale immersion tank system. Side rot did not develop in surface-sterilized fruit sampled during commercial packing operations, but it did occur in samples that were not surface-sterilized. Results support the hypothesis that soilborne or deposited airborne spores may be brought into packinghouses on fruit surfaces or harvest bins and be redistributed to uninfested fruit in immersion tank solutions.