By Howard Bryman
Despite generations of careful crop management, stringent screening, and strict quarantine protocols, the fungus Hemileia Vastatrix, root cause of the crop-destroying plant disease coffee leaf rust (CLR) found its way into Hawaii.
The first signs of infection on plants in the state were found late last month on a residential property in the Big Island town of Hilo. In correspondence with STiR Magazine, Christopher A. Manfredi, president, Hawaii Coffee Association at that time also reported some then-unconfirmed discoveries of CLR in Kona. The Hawaii Department of Agriculture (HDOA) has since announced that while samples taken from Hilo have tested negative for CLR, samples collected by a farmer in the Holualoa area of Hawaii Island on October 31 have tested positive.
"These appear isolated so far, and surveys are continuing," Manfredi told STiR.
The U.S. Department of Agriculture (USDA) National Identification Services has reported that the telltale yellow-orange splotches have also been spotted on the tops of leaves on coffee trees in Maui. These infections are estimated to be at least a year old, according to Manfredi.
“We are hosting virtual multi-agency meetings weekly among HDOA, USDA, UH CTAHR [University of Hawaii College of Tropical Agriculture & Human Resources], lawmakers and regulators, the research community and industry professionals both in Hawaii and across the globe,” said Manfredi. “It’s all hands on deck.”
Exactly how the fungus managed to find its way onto the islands is unknown, and may never be known. The fungus was first discovered in Indonesia in 1869, and then proceeded to devastate the coffee industry there over the decade that followed. In more recent years rust has wreaked havoc on crops and livelihoods in Central and South America. Untreated rust leads to premature defoliation, resulting in anywhere from a 30 to 80% reduction in crop yield the subsequent year.
According to HDOA, coffee cherry production in Hawaii for the 2019-2020 season totaled 27.3 million pounds (cherry basis) during the 2019-20 season, amounting to a value of roughly $54.3 million. Manfredi told STiR it's not yet known what effect the recent discovery may have on crops in the near future or the long term.
"This year will be fine in terms of harvest," said Manfredi. "We are trying to identify the race of rust and learning how aggressive it might be. I think [the] long-term response will include a transition to more rust resistant varieties. Our short-term response is multi- faceted."
Coffee plants brought to Hawaii and that are relocated between islands are already required to complete a one-year quarantine period in a HDOA quarantine facility and then undergo inspections again prior to shipping. Imported green coffee beans must undergo fumigation, per state regulations. These efforts helped preserve the islands' status as the only remaining major coffee-producing region on Earth unaffected by La Roya, as it is known in the Americas. Now that the streak is over, additional focus is shifting towards mitigation.
"Depending on the locale and what the ongoing surveys reveal, spraying with fungicide may slow the spread and give us time," said Manfredi. "Containment and/or eradication measures are currently being evaluated and/or implemented. We are training growers on what to look for and how to report it. Further, it’s important to stress that it’s vitally important to keep your trees healthy. Good farming practices improve plant health and the trees’ natural ability to fight disease."