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First came the brown and beige spots on the leaves of her avocado trees. Then the Kula farmer watched her avocado harvest dwindle to a tiny fraction of past years.
She learned the spots were caused by avocado lace bugs, a new invasive species that poses a true threat to the once-reliable Maui crop. The tiny insects establish colonies on the underside of avocado leaves, robbing them of nutrition. The leaves wither and fall off.
Avocado lace bugs were not thought to be on Maui when the state Department of Agriculture first identified the insects on Oahu in December 2019. They now infest avocado trees from Haiku to Lahaina, says University of Hawaii Assistant Extension Agent Rosemary Gutierrez-Coarite, Ph.D.
"In dry areas it is worse, you can see that in the trees, their leaves are dry and they are falling down," Gutierrez-Coarite said. "I have trees in Lahaina without leaves."
She recommends tree owners consider a rotation of organic and nonorganic sprays, including systemics -- which are absorbed into the plant and not just topical. Without treatment, she says, trees lose their leaves and photosynthesis stops.
"Eventually that tree will grow more leaves, but the production of fruits by the tree will decrease to almost zero," she said.
Gutierrez-Coarite is part of a small cadre of guardians on the front lines of Maui's battle to protect our unique island habitat. While most of that work is done far from the spotlight, this week in The Maui News we learned about a Hana crew that is scheduled to receive a rare worldwide nod for its battle against the highly invasive plant, miconia.
The Maui Invasive Species Committee's Hana miconia crew is to be featured in an episode of the BBC Studios' "The Green Planet" episode titled "Human Worlds." The show with the Maui crew makes its public debut on PBS Hawaii on Aug 6.
Some invasives are imported on purpose, as miconia was by a Hana nursery back in the early 1970s. And others slip in by mistake, perhaps in a potted plant or tread of a shoe. Former state entomologist Mach Fukada says globalization makes it almost impossible to stem the tide.
"The best analogy is, I feel like I'm the little Dutch boy with my finger in the dike, but the water is coming over the top," Fukada said Thursday. "I see the potential to only get worse."
Friday was Fukada's last day at his post with the state Department of Agriculture's Plant Pest Control Branch. He is slated to start this coming week as program manager and instructor for University of Hawaii Maui College's Agriculture and Natural Resources Department. We wish him the best and thank him for his years of service.
When our plants get sick, our crops fail or a colony of red fire ants moves in, we turn to experts for help. The agencies, programs and nonprofits that protect our fragile island environment deserve our support.
* Editor's note: Gutierrez-Coarite invites growers with questions to email her at gr6@hawaii.edu.