‘Devastating’ coffee leaf rust found in Haiku

How fungus got to Maui is not clear

The effects of the coffee leaf rust are shown in this photo. The “devastating” fungus to coffee plants was found in managed and wild coffee plants in Haiku. Hawaii Department of Agriculture photo

The Maui News

The coffee leaf rust, “one of the most devastating pests of coffee plants,” has been tentatively identified on plant samples collected on Maui from managed and wild coffee in Haiku, the state Department of Agriculture said.

The leaf rust is established in all other major coffee growing areas of the world but had not previously been found in Hawaii, the state Agriculture Department said.

The results were received by the Agriculture Department from the University of Hawaii College of Tropical Agriculture and Human Resources, a news release Monday said. Samples also have been sent to the U.S. Department of Agriculture National Identification Services on the Mainland for official confirmation of this federally regulated pathogen.

On Wednesday, leaves from managed coffee in the Haiku area of Maui displaying fungus symptoms were turned in to the state Department of Agriculture on Maui. Subsequent surveys in the area found plants with symptoms at three additional locations, two of which were in wild coffee.

Currently, the state Agriculture Department is continuing its survey efforts on Maui and is extending those efforts statewide as well.

“It is unknown at this time how the rust got to coffee plants on Maui or how long it has been there,” said Phyllis Shimabukuro-Geiser, chairwoman of the state Board of Agriculture. “We appreciate the assistance of the multiple agencies that are helping us to determine the extent of this infestation and how coffee leaf rust may have been introduced into the state.”

The state Agriculture Department has sent a memo to members of the coffee industry throughout the state to alert them to the situation.

The leaf rust 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 percent, the department said.

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.

The fungus may also infect young stems and  berries.

While there are fungicides that may be used to help control the fungus, one of the key factors to any pest management program is good sanitation practices. Regular pruning and training of the coffee tree helps to prevent over-cropping and maintain a healthy field. These practices help to improve air circulation and also to open up the canopy to allow proper fungicide spray coverage. Good weed control is an important factor as it keeps competition for vital nutrients low, thereby reducing the susceptibility to the rust, the department said.

Coffee leaf rust, Hemileia vastatrix, was first discovered in Sri Lanka in 1869 and is now found in the major coffee-growing regions of the world, including Southeast Asia, Africa and Central and South America.

Hawaii has strict importation rules requiring all imported green coffee beans for roasting and associated packing materials be fumigated prior to entering the state to ensure beans are free of pathogens and insect pests. These rules also subject coffee plants and propagative plant parts to strict quarantine requirements if imported to Hawaii, including a quarantine on all imported coffee plants for a minimum of one year in a state-run quarantine facility.

To report possible coffee leaf rust infestations on any island, call the state Agriculture Department Plant Pest Control Branch at (808) 973-9525.

For more information on coffee leaf rust go to the UH-CTAHR webpages at https://www.hawaiicoffeeed.com/coffee-leaf-rust—nko.html and http://www.extento.hawaii.edu/kbase/crop/Type/h_vasta.htm.


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