Disease Incidence-Inoculum Dose Relationships for Botrytis cinerea and Penicillium expansum and Decay of Pear Fruit Using Dry, Airborne Conidia.

The objective of this research was to determine quantitative relationships between incidence of pear fruit decay and inoculum dose of Botrytis cinerea and Penicillium expansum using dry conidia applied to wet or dry pears in a settling tower. On wet fruit, incidence of gray mold fruit rot increased from 0.1 to 83.1% as the airborne concentration of B. cinerea conidia increased from 0 to 8.6 spores per liter of air. Significantly less decay occurred in fruit inoculated dry compared to wet, particularly in fruit wounded after inoculation. Incidence of blue mold increased from 1 to 100% as the airborne concentration of P. expansum conidia increased from 0.1 to 803.5 spores per liter of air. Blue mold incidence was not affected by fruit wetness or time of wounding relative to inoculation. All regressions of decay incidence versus airborne and surface conidial concentrations were highly significant (P = 0.01).