Link to home

Infection Courts and Timing of Infection of Apple Fruit by Phacidiopycnis washingtonensis in the Orchard in Relation to Speck Rot During Storage

November 2014 , Volume 98 , Number  11
Pages  1,467 - 1,475

P. Sikdar , Department of Plant Pathology, Washington State University, Pullman 99164 ; M. Mazzola , United States Department of Agriculture-Agricultural Research Service (USDA-ARS), Tree Fruit Research Laboratory, 1104 N. Western Ave., Wenatchee, WA 98801 ; and C. L. Xiao , USDA-ARS, San Joaquin Valley Agricultural Sciences Center, 9611 S. Riverbend Ave., Parlier, CA 93648



Go to article:
Accepted for publication 28 April 2014.
Abstract

Phacidiopycnis washingtonensis is the cause of speck rot, a recently reported postharvest fruit rot disease of apple. The pathogen is believed to incite infections in the field, and disease symptoms become evident only during storage. To determine the timing of apple fruit infection in relation to development of speck rot in storage, ‘Red Delicious’ and ‘Fuji’ apple fruit were inoculated in the orchard with P. washingtonensis at different times during the growing season, harvested, and monitored for decay development during storage at 0°C. Fruit inoculated in both field and laboratory also were used to identify the infection courts and mode of apple fruit penetration by P. washingtonensis. In all 3 years, stem-end speck rot and calyx-end speck rot developed during cold storage on fruit inoculated during the growing season, regardless of inoculation time; and the incidence of total speck rot in storage increased as the fruit inoculation time approached harvest. On fruit floral parts, the pathogen colonized sepals at higher rates than stamens. Availability of naturally occurring necrotic tissues favored the colonization of the fungus on sepals. Histological studies indicated that infection occurred through micro-cracks on the surfaces of pedicels and sepals of the fruit, and invasion of these tissues was restricted between the cuticle and epidermis. Findings of this study will assist in the development of effective control strategies for speck rot.



This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2014.