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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Food Quality Laboratory » Research » Research Project #443505

Research Project: Development of Conventional and Organic Tools to Manage Postharvest Decay of Pome Fruits

Location: Food Quality Laboratory

Project Number: 8042-42430-003-002-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: May 1, 2023
End Date: Jan 31, 2025

Blue mold is a problem that growers want to get control of and its important to get this work done. Hence, the main objective of this project is to deliver new controls and methods to control postharvest decay of stored pome (apple and pear) fruits. The objectives are: 1) to determine and optimize alternative postharvest treatments using conventional and alternative products to eliminate fungicide resistant and sensitive inoculum on bins and apples and 2) to formulate and disseminate sanitization protocols and procedures for postharvest disease management.

Wooden and plastic bins will be used for the proposed experiments. They will be sanitized and verified by swabbing the interior bin surfaces and plating the swabs on Petri plates containing Potato Dextrose Agar to enumerate total numbers of fungal colonies. Once bins are deemed sterile, they will be inoculated with water only, low, or high inoculum loads of P. expansum T1 strain transformed with the GFP gene containing the hygromycin resistance marker for selection. Conidial suspensions of P. expansum T1 will be obtained and bins will be incubated at 27°C for 1 week to allow infestation. Treatments will include five bins for both inoculum levels for: steam, fogging with thyme guard (1%), a proprietary volatile compound (250mM), or three commercial postharvest fungicides at maximum rates per the label. Once all treatments are complete, inoculated and non-inoculated control bins will be stored at 1°C and sampled after 1, 3, and 6 months. After each timepoint, bins will be removed from cold storage without treatment and the pathogen will be recovered from all bins and treatment combinations to determine colony forming units. Plates will also be visualized for green florescence using UV light. We will examine bin surfaces using a dissecting scope equipped with the proper filters and a UV light source to visualize bin surfaces to identify if the pathogen can colonize one material (wood vs. plastic) better than the other and to evaluate the efficacy of the bin treatments to reduce blue mold inoculum levels. Colony forming unitss will be also counted 24 h after all the treatments are complete to evaluate the shortterm effect of the fungicide treatments. The experiments for wooden and plastic bins will be performed separately and each experiment will be arranged in a completely randomized factorial design with two factors, inoculum level and fungicide treatment.