Coffee Leaf Rust Discovered on All Major Islands of Hawaii

A coffee plant showing leaf rust spots on Hawaii Island. November 2020 photo from the Hawaii Board of Agriculture.

The highly contagious, crop-killing coffee leaf rust disease (CLR) has now been discovered on all major Hawaiian islands, according to the Hawaii Department of Agriculture (HDOA).

The agency informed the public of the discovery of the rust-causing pathogen, Hemileia Vastatrix, on coffee samples on the islands of Kauai and Molokai, this week. Following lab testing, the HDOA believes rust may have been present among some Kauai coffee plants for at least six months.

A Kauai coffee farmer informed the agency of the possibility of CLR, while the samples from Molokai came from feral coffee plants. The agency believes plants there may have been affected for at least three months.

The spread of the disease throughout Hawaii has come despite the state’s strict quarantine measures for agricultural products, including emergency measures put in place after the discovery of leaf rust last October on the island of Maui.

By November, the disease had been identified on the big island of Hawaii. This past January it was found on plants from Oahu and Lanai, and CLR became a major issue at the Hawaii Coffee Association annual conference last month.

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Since the first detection, the Hawaii Board of Agriculture (Board) approved an interim administrative rule which restricted the movement of “coffee plants, plant parts and other CLR hosts” from infected islands to try to stop the spread of the disease. With the detection of CLR statewide, HDOA is reassessing these restrictions, which are currently scheduled to expire on Nov. 21.

First identified in the 1860s in both East Africa and Sri Lanka, coffee leaf rust has since made its way all over the coffee-growing world. Infections can spread quickly, preventing plant leaf and berry growth during infection and in subsequent years.

Smallholder coffee farmers in parts of South America, Central America and Mexico are still reeling from a devastating leaf rust epidemic that became widespread in 2012.

Resources for Hawaii coffee producers can be found here.