University of Hawaii researchers are asking the public for help after the discovery of a new pest of coffee.
The disease symptoms, which have not been reported anywhere else in the world, are circular yellow or yellow-green lesions, or spots, about a quarter-inch in diameter on the leaves and stems. Anecdotal evidence suggests that it renders the coffee cherries unusable, though it is not yet known what the lesions look like on the cherries.
In January 2014, a coffee farmer contacted the UH Manoa College of Tropical Agriculture and Human Resources to ask about the spots on his coffee leaves. Scientists found several symptomatic plants in two locations at the farm, and they could also see some symptomatic plants across a fence at a neighboring coffee farm.
Further analysis revealed a new species of virus was found in the coffee, possibly transmitted by mites that can spread on wind currents and by the movement of infected plant material.
“We don’t know yet how much of a problem we are dealing with,” said Scot Nelson of CTAHR, “but based on Hawaii’s experience with other new plant diseases, we need to get started dealing with it as soon as possible.”
After reporting the plants, growers can follow the tips provided:
- Isolate them and refrain from transporting cuttings, cherries, leaves or other plant material from them to another site.
- Sterilize pruning tools that have been used on symptomatic plants with a propane torch or a 10 percent bleach solution before pruning other plants.
- Control mites, the presumed vector, so that they do not move to new plants, with neem oil, which is available at many farm and garden supply and home improvement stores and online.
- Destroy treated plants by burning them (a permit may be required) or cutting down and bagging them in heavy-duty garbage bags (woody parts may be chipped before bagging). The bags should left to sit in the sun for a few days, after which the plants can be composted.