Coping with Coffee Leaf Rust: EPA considers exemption for fungicide

  • Coffee berries are seen at Heavenly Hawaiian Coffee Farm in Holualoa. (Tom Linder/West Hawaii Today)

Farmers on the Big Island may be getting another tool to help combat coffee leaf rust.

On March 16, the Hawaii Department of Agriculture filed request for specific exemption from the U.S. Environmental Protection Agency to allow farms to use a fungicide – Priaxor Xemium – on coffee plants. Currently, the fungicide is not labeled for use on coffee plants by the EPA, but has been allowed on a wide range of plants including leafy vegetables, strawberries, tomatoes, soybeans, wheat and more since 2013.

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This action follows Gov. David Ige’s February emergency declaration for Hawaii’s $56 million coffee industry due to the presence of CLR.

The EPA’s review could take as many as 45 days. While news of a new tool to fight CLR is a welcome sign for many coffee farmers in West Hawaii, some worry that after waiting 45 days, the help may come too late.

“CLR will become very, very aggressive when it is hot and moist,” said Bill Myers, general manager of the Heavenly Hawaiian Coffee Farm. “You’re looking at April, May: those months, you’re going to start getting real spread of CLR and very aggressive damage.”

Other farmers, however, have expressed skepticism for using the fungicide at all, citing worries ranging from environmental concerns to cost. Environmental worries include toxicity to fish and aquatic invertebrates in runoff, while cost concerns largely stem from having to use multiple new pesticides, since fungicide treatments must be rotated. Colehour Bondera – president of the Kona Coffee Farmers Association – laid out the financial situation many small farms face.

“You’ve got to rotate around if you’re going to use these chemicals,” Bondera said. “With Coffee Berry Borer, you can use the single product and apply it three, four times, and you can get covered 50% by the HDOA’s support program. But if you have to apply six or eight pesticides, and they’re even more expensive than what people are using for CBB, and you have to add additional fertilizer, the totals aren’t going to balance out economically for the small farms to be able to do it.”

Potential relief for some of these costs is being considered in the state legislature. Senate Bill 855 SD1 would extend the pesticide subsidy program through 2023 and provide extra money to farmers specifically for CLR. The bill was most recently passed by the House’s Agriculture Committee on Tuesday and has been referred to the Finance Committee.

Bondera warns that even if the fungicide’s use is approved and subsidized, it’s still an impermanent solution.

“I think it’s going to help only in the very short term,” Bondera said. “I still think we need to come up with much longer-term systemic strategies that aren’t necessarily just rotating the chemicals through for balanced pesticide use, but instead are what we can change about the system.”

Another action may be taken on March 23, when the Board of Agriculture reviews a HDOA proposal to expand the CLR infested areas to include Lanai and Oahu after the fungus was detected on each island in January. This action would add coffee and related CLR host material from both islands to the quarantine restrictions set in the Plant Quarantine Interim Rule 20-1 that took effect in November.

According to the HDOA, 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% and 80%.

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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.

CLR, 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.

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