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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Research Project #439509

Research Project: Plant Safety, Horticultural Benefits, and Disease Efficacy of Essential Oils for use in Organically Grown Fruit Crops: From the Farm to the Consumer

Location: Tropical Plant Genetic Resources and Disease Research

Project Number: 2040-21000-018-005-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Oct 1, 2020
End Date: Aug 31, 2025

The objective of this work is to test on-farm disease suppression of applications of various concentrations and mixtures of Essential Oils (EOs) on peach (FL, SC), blueberry (FL, GA), mango (FL, HI), and avocado (FL, CA) through multi-year experiments.

Fungicide efficacy experiments to control anthracnose and powdery mildew affecting mango inflorescence will be set up as a complete randomized block design or a completely randomized design depending on the configuration of the orchard and conducted on a 5 acre certified organic farm growing the variety ‘Rapoza’. The inflorescence will be treated using a standard farming practice of elemental sulfur and copper, and horticultural essential oils (EOs). Based on canopy size and tree availability, 8 to 16 trees will be randomly selected for each treatment and grouped into four replicates. Ten similar size panicles per tree and spaced equally around the tree will be tagged with flagging tape and monitored up to fruit harvest. Panicles will be observed for disease incidence, disease severity, and number of harvestable fruits per panicle. Applications of treatments will begin at bud formation or according to the pesticide label. Twenty to thirty mature fruits will be selected for post-harvest disease incidence and severity. Postharvest assays will be carried out to find how long treated fruit by EOs in the field can stay diseases free on the shelf versus grower’s cultural practices. Twenty to thirty asymptomatic mature fruit at the same stage of ripeness will be randomly selected from each treatment. Fruit will be stored at laboratory room temperature (25°C) and kept in commercial fiberboard cartons or plastic crates. Fruit will be evaluated at intervals of 3 and 7 days for disease incidence and severity until overripe. Postharvest diseases will be identified by morphological and/or molecular techniques.