Scientists Seek Citizens’ Help With New Coffee Threat

Hawaii researchers have discovered a new coffee pest, the emaravirus, that could pose a new threat to Hawaii’s $35 million coffee industry.

Scot Nelson and Michael Melzer, faculty at the UH Mānoa College of Tropical Agriculture and Human Resources, said the emaravirus causes circular yellow or yellow-green lesions, or spots, about one quarter-inch in diameter on the leaves and stems of the plants.

It was discovered in January when a Captain Cook farmer noticed the unusual spots and contacted Nelson via a plant disease diagnosis app he created, The Plant Doctor.

Nelson had never seen the disease before, and its symptoms have not been reported anywhere else in the world, he said.

Melzer visited the farm with CTAHR extension agent Andrea Kawabata, who has been working closely with farmers to combat another pest, the coffee berry borer, and found the spots on leaves in two locations at the farm, and on some plants across a fence at a neighboring coffee farm.

The state Department of Agriculture plans to begin preliminary surveying next week which will help determine whether more extensive surveying is required, Nelson said.

“We’re hoping that it’s only in a small area and we can eradicate it,” he said. “It depends on what we find in the survey. It might not be a problem.”

In the meantime, he’s hoping “citizen-scientists” will begin reporting any of the disease symptoms among their plants.

A survey of farms to determine the spread of the disease will take time, Nelson said, so individuals are encouraged to report on their own crops as soon as possible, in a “citizen science” effort.

Little is known yet about how the disease works though anecdotal evidence suggests it makes coffee cherries unusable. But it is not yet known what the lesions look like on the cherries, said Nelson, who has created a web site to publicize the disease.

Melzer’s analysis said a new species of virus similar to emaraviruses was found in the symptomatic coffee, but there is no specific evidence that the virus causes the disease. No emaraviruses have ever been reported to infect coffee, he said.

One concern is that emaraviruses are transmitted by eriophyid mites, which can be spread on wind currents as well as by the movement of infected plant material, suggesting the possibility that it could spread quickly.

Anyone who sees symptoms of the disease at their farm should contact Scot Nelson at 956-6741, snelson@hawaii.edu, or via his Plant Doctor app. Citizen-scientists may also contact Andrea Kawabata at andreak@hawaii.edu.

“We don’t know yet how much of a problem we are dealing with,” Nelson said, “but based on Hawai‘i’s experience with other new plant diseases, we need to get started dealing with it as soon as possible.”