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ARS Home » Pacific West Area » Parlier, California » San Joaquin Valley Agricultural Sciences Center » Commodity Protection and Quality Research » Research » Publications at this Location » Publication #305707

Title: Control of speck rot in apple fruit caused by Phacidiopycnis washingtonensis with pre- and postharvest fungicides

item Xiao, Chang-Lin
item BOAL, R - Washington State University

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 6/30/2014
Publication Date: 11/1/2014
Citation: Xiao, C., Boal, R.J. 2014. Control of speck rot in apple fruit caused by Phacidiopycnis washingtonensis with pre- and postharvest fungicides. Phytopathology. 104(Suppl. 3):S3.132.

Interpretive Summary:

Technical Abstract: Speck rot caused by Phacidiopycnis washingtonensis is a recently reported postharvest fruit rot disease of apple. Infection of apple fruit by the fungus occurs in the orchard, but symptoms develop during storage. In this study, selected pre- and postharvest fungicides were evaluated for control of speck rot. Fruit were inoculated with the conidial suspension of the pathogen in the orchard 3 weeks before harvest. Part of the fruit was sprayed with a premixed formulation of pyraclostrobin and boscalid (Pristine), thiophanate-methyl, or ziram at 7 or 14 days before harvest, and the remaining fruit were either not treated as controls or dipped in fludioxonil, pyrimethanil or thiabendazole solutions after harvest. Fruit were stored at 0°C and monitored periodically for speck rot symptoms for up to 9 months. Over the 3 seasons, Pristine, thiophanate-methyl and ziram reduced speck rot by 5-87%, 0-80%, and 53-82%, respectively, compared to the nontreated control. Fludioxonil, pyrimethanil and thiabendazole reduced speck rot by 93-100%, 96-100%, and 77-95%, respectively. Postharvest fungicide treatments were more effective than preharvest fungicides tested in this study. The results indicate that although infection of apple fruit by P. washingtonensis occurs before harvest, a preharvest fungicide applied near harvest or a postharvest fungicide treatment applied prior to storage can be an effective strategy for control of speck rot in stored apple fruit.