Coffee Left Rust Found on Holualoa Farm

Coffee Leaf rust identified on a farm in Holualoa, according to the Department of Agriculture. (PC: Department of Agriculture)

Coffee leaf rust (CLR) has been confirmed on coffee plants on Hawai‘i Island by the U.S. Department of Agriculture National Identification Services.

The samples were collected by a grower on a farm in the Holualoa area on Oct. 31. Samples from Hilo, mentioned in an earlier news release, were negative for CLR. Earlier in October, CLR was detected and confirmed in the Haiku area of Maui. CLR has not been detected on other islands.

CLR is one of the most devastating pests of coffee plants and is established in all major coffee-growing areas of the world, but had not previously been found in Hawai‘i prior to its recent discovery on Maui and Hawai‘i Island.

“Coffee is one of Hawai‘i’s signature crops, of which production was estimated to be $54.3 million in 2019,” said Phyllis Shimabukuro-Geiser, chairperson of the Hawai‘i Board of Agriculture. “As surveys continue across the state, the Hawai`i Department of Agriculture is preparing to establish interim rules that will hopefully prevent the spread of the fungus to uninfested islands.”

The Hawai‘i Department of Agriculture (HDOA) Advisory Committee on Plant and Animals has scheduled a meeting on Nov. 13 at 1:30 p.m. to consider an interim rule to restrict the movement of coffee plants and coffee plant material from islands found to have CLR to islands on which the fungus has not been detected. Information on the meeting via Zoom is available at: http://hdoa.hawaii.gov/blog/main/pqmtgs/.

CLR can cause severe defoliation of coffee plants. Infected leaves drop prematurely, greatly reducing the plant’s photosynthetic capacity. Vegetative and berry growth are reduced depending on the intensity of rust in the current year. Long-term effects of rust may include dieback, which can have a significant impact on the following year’s yield, with some researchers estimating losses between 30 percent and 80%.

The first observable symptoms are yellow-orange rust spots, appearing on the upper surface of leaves. On the underside of the leaves, infectious spores appear resembling a patch of yellow- to dark orange-colored powder. These young lesions steadily increase in size with the center of the lesion turning necrotic and brown, with the infection eventually progressing up the tree. CLR may also infect young stems and berries.

HDOA’s Plant Pest Control Branch has prepared a field guide to aid in the detection and reporting of possible CLR infections. The field guide maybe found at: http://hdoa.hawaii.gov/pi/ppc/new-pest-advisories/.