The state Department of Agriculture announced Tuesday it has confirmed the detection of coffee leaf rust (CLR) on Kauai and Molokai. The coffee plant pathogen has now been found on all major Hawaiian Islands.
On June 28, a commercial coffee grower in Kilauea, Kauai, reported a possible CLR infection. The Department of Agriculture collected samples and CLR was confirmed on July 9. Preliminary assessments indicate that CLR had been on Kauai for at least six months.
On June 14, Department of Agriculture staff conducted a survey of feral coffee plants on Molokai. A low-level infestation was detected on two coffee plants in a field of 50 wild coffee plants in Kaunakakai and CLR was confirmed on June 23. Subsequent surveys detected more infestations on the east side of the island. It is estimated that the infestation on the east side had been there for at least three months.
CLR was first detected in the state in October on the Big Island and Maui, and subsequently detected on Oahu and Lanai in January.
Since the first detection, the state Board of Agriculture approved an interim administrative rule that 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, the board is reassessing these restrictions; however, they will remain in place until further action is taken by the board or the interim rule lapses in November.
CLR is a devastating coffee pathogen and was first discovered in Sri Lanka in 1869 and can cause severe defoliation of coffee plants resulting in greatly reduced photosynthetic capacity. Depending on CLR prevalence in a given year, both vegetative and berry growth are greatly reduced. There are multiple long-term impacts of CLR, including dieback, resulting in an impact to the following year’s crop, with estimated losses ranging from 30% to 80%.
2020-2021 Hawai`i Coffee Season Statistics (National Agricultural Statistics Service): https://www.nass.usda.gov/Statistics_by_State/Hawaii/Publications/Fruits_and_Nuts/Coffee-01-26-2021.pdf