THE IMPORTANCE OF WOUNDS IN INFECTION OF PEAR FRUIT BY PHIALOPHORA-MALORUM AND THE ROLE OF HYDROSTATIC-PRESSURE IN SPORE PENETRATION OF WOUNDS

Pear fruits (cv. Bosc) were not infected by Phialophora malorum via lenticels under conditions of bruising, hydrostatic pressure, or 6 mo of exposure to a range of spore concentrations without puncture wounding. Methylene blue solution penetrated approximately 2% of fruit lenticels examined. Dye penetration into fruit was facilitated by artificial bruising of lenticels. Hydrostatic pressure from immersion of fruit in aqueous suspensions of P. malorum spores at depths from 10 to 100 cm influenced the frequency of infection in fruit puncture wounds <2 mm in diameter. Larger wounds were infected independently of immersion depth. Germination of spores of P. malorum was stimulated in water in which wounded fruit or fruit with epicuticular wax removed had been soaked, as compared to water in which whole fruit had been soaked.