Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2017
Publication Date: 3/7/2018
Citation: Aguilar, C.G., Mazzola, M., Xiao, C. 2018. Control of bull’s-eye rot of apple caused by Neofabraea perennans and Neofabraea kienholzii using pre- and postharvest fungicides. Plant Disease. 102(5):905-910. https://doi.org/10.1094/PDIS-09-17-1363-RE.
Interpretive Summary: A large proportion of the Washington State apple fruit crop is stored for long periods prior to sale domestically or shipped for export. During this period, potential exists for the development of fruit rot that is caused by fungi. One such disease, bull’s eye rot, is not noticeable when the fruit is harvested but only becomes evident after storage for a period of 2 to 3 months. Studies were conducted to determine whether effective control of the disease could be attained with certain fungicides if applied in the orchard prior to fruit harvest or when applied after harvest but before fruit were placed in storage. Specific fungicides were identified that were capable of providing effective disease control when utilized either as a pre-harvest treatment or in a post-harvest setting. The effective fungicides are also used to control other post-harvest diseases. Due to the common use of these fungicides, their use for control of bull’s eye rot must applied judiciously to minimize the potential for the development of fungicide resistance in populations of the fungi that cause these important diseases.
Technical Abstract: Bull’s-eye rot is a major postharvest disease of apple caused by several fungi belonging to the Neofabraea and Phlyctema genera. Chemical control of these fungi is a crucial component of disease management for apples that are conventionally grown. The efficacy of several pre-harvest and postharvest applied fungicides were evaluated to identify effective chemistries that can control bull’s-eye rot incited by Neofabraea perennans and Neofabraea kienholzii on apples. In general, the pre-harvest fungicide thiophanate-methyl was found to be effective at reducing disease caused by N. perennans and N. kienholzii. Two postharvest fungicides, thiabendazole and pyrimethanil also provided disease control that was far superior to other chemical compounds evaluated in this study. The efficacy of thiabendazole and pyrimethanil was unaffected by application method (fungicide dip compared to thermofog). Despite providing satisfactory control of bull’s-eye rot, integration of these three chemicals into disease management programs should proceed judiciously with consideration of their impact on the development of fungicide resistance and influence on diversity in populations of apple postharvest pathogens.