Could essential oils be used to fight fruit fungus?

  • Mangoes that have been affected by fungal disease are gathered in a box. (Photo courtesy Lionel Sugiyama/USDA Agricultural Research Service in Hilo)

  • A mango is affected by fungal disease. (Photo courtesy Lionel Sugiyama/USDA Agricultural Research Service in Hilo)

While plant disease is difficult to control in organic fruits, researchers at the University of Hawaii are studying essential oils to see if they might provide a solution.

Finding ways to improve feasibility and long-term profitability of organic fruit production is the basis of a nearly $2 million Organic Agriculture Research and Extension Initiative awarded by the U.S. Department of Agriculture to a team of 15.


The team includes Associate Extension Agent Andrea Kawabata of the University of Hawaii at Manoa’s College of Tropical Agriculture and Human Resources’ Cooperative Extension in Kailua-Kona.

The project is called, “Plant Safety, Horticultural Benefits, and Disease Efficacy of Essential Oils for Use in Organically Grown Fruit Crops: From the Farm to the Consumer.”

“The idea to research essential oils as a fungicide came about because there are very few fungicides that apply to tropical food crops or anything organically grown,” said plant pathologist Lisa Keith, who works for the USDA-Agricultural Research Service in Hilo. “There has been some lab research, but there hasn’t been much field research.”

Hawaii and four other states — Florida, South Carolina, Georgia and California — are evaluating the effectiveness of organically certified plant-based essential oils on major fruit pathogens.

Researchers are studying ways to battle pathogens that cause fungal diseases such as avocado scab, powdery mildew and anthracnose in targeted tropical and temperate fruit crops.

“When it comes to essential oils, there is not a one size fits all,” Keith said. “While they could work for one fungus, they could not work for 25 others.”

CTAHR researchers and extension faculty in Hawaii are working closely with organic mango and avocado growers to guide the research into essential oils.

“This would have a huge impact on producers and growers, because our long-term goal is profitability and sustainability,” Keith said. “Specifically, this could improve production locally, therefore allowing less imports of organic fruit.”

Research will begin in the lab to see if essential oils are effective against pathogens found in the field. After laboratory work, field producers will work in collaboration with researchers to sort out the best application rate and timing.

“Some pathogens are visible in the field, some occur during post harvest, some are infected in the field, but you don’t see it until it’s time to harvest,” Keith said. “All of our research will try and determine if essential oils improve shelf life of organic fruits.”

There are currently methods, which usually contain copper or sulfur, growers use to battle pests and diseases, but they have not been proven sustainable or as environmentally friendly as essential oils, researchers say.

“Growers are always looking for other tools to make things safer for the environment that can also better control pests and diseases they deal with,” Kawabata said. “Hopefully, the research helps us find another tool for farmers to use.”

The goal of the essential oil research is for crop producers to improve their market competitiveness by adopting organic practices set forth by the researchers as a result of the data gathered.

The project is currently in its infancy and will span over four years. While there hasn’t been conclusive data yet, researchers are optimistic about their studies.

“Hopefully, we can find something that works better for organic farmers,” Kawabata said. “If not, we can learn from these projects and maybe find a way to incorporate our findings into something else.”


“The things we’ve seen from other states and that data we’ve collected here so far show that the promise is there,” Keith said.

Email Kelsey Walling at

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