The timing of the avocado lace bug’s arrival in Hawaii couldn’t have been any worse for Daniel Caroll, who was preparing to expand his avocado business from a small plot on the North Shore to a 10-acre farm in Waialua.
“One week I got like at least six emails and text messages from concerned friends and family, like, ‘what are you going to do?’” he said.
The lace bug was first identified on Oahu at the end of 2019, and has since spread to Maui and the Big Island. The small bug can have a big impact, sucking nutrients out of avocado leaves and leaving the tree unable to bear fruit.
In addition to running Hua Orchards, which has local avocados and citrus, Carroll is also a farm coach with the University of Hawaii’s farmer training program, Go Farm Hawaii. This proved a key bridge to researchers at the university’s college of tropical agriculture like Jensen Uyeda, who connects farmers in Hawaii to new research and resources.
Uyeda, Carroll and other experts worked together to find a blend of affordable essential oils to spray on the avocado leaves and even designed a novel backpack sprayer to use in the field.
“I think initially the lace bug was really scary,” Uyeda said. “Having worked with it now for the last year and a half or so, we’ve been able to better understand how to manage it.”
After a lot of trial and error, Carroll said their essential oil solution is 92% effective against the pest and went forward with the expansion of his farm last November. Now he has 5 acres of avocado and citrus trees in the ground, with another large-scale planting planned later this year. Although he does find the pest on his plants annoying, it’s been manageable.
“We got lucky,” he said.
The avocado lace bug is just the latest in a long line of invasive pests threatening local food production. It’s estimated red fire ants cost the state more than $2 million a year and fruit fly infestations cost farmers almost $300 million a year. Hawaii has almost as many invasive species as the other 49 states combined.
At a recent live-taping of Civil Beat’s Hawaii Grown podcast, Uyeda and Glenn Martinez, a Waimanalo farmer and pest expert, talked about different solutions to help farmers tackle pests and took questions from the audience about the growing threat.
Importing Ideas, Not Insects
Many farmers across Hawaii reach out to Glenn Martinez when they spot a new or confusing bug on their land because Olomana Gardens, his Waimanalo farm, boasts an ever-expanding microscope collection and array of high-quality cameras.
“The fun thing that we’re doing with the microscopes is trying to take pictures that you can’t see with your naked eye,” he said.
Two very different pests can look similar to the naked eye, and with new pests coming in seemingly “every week,” according to Uyeda, identification is the first step to management.
Before the pandemic Martinez regularly traveled to farms around the world to try and find low-cost solutions that didn’t rely on pesticides.
He regularly floods his vegetable fields for a couple of hours to kill off slugs and ants, a tip he learned from farmers in South Korea and China. And in South Korea he saw another innovation that he’d love to try in Hawaii: wind socks on large poles at the edge of each farm.
“You see a lady go out there and she pulls down like she’s lowering the flag,” he said. “She takes a look … and she gets on the phone and she calls it in and an alert goes out to all the farms that are downwind of them to tell them what pest is blowing in that day.”
He thinks this could be a solution for communities on Molokai and Kauai because trade winds regularly spread pests to closely-grouped farms. If they had a heads-up about incoming pests, they could temporarily cover their plants and set up other pest deterrents. But the idea only works if all the farmers participate.
“We don’t seem to have the cooperation,” he said. “We seem to be isolationist, we all struggle on our own.”
Collaboration Is Key
Martinez also said the level of collaboration between farmers and the government was greater in South Korea, aided by more resources.
The Hawaii Department of Agriculture’s biosecurity program spent over $5 million last year, but Martinez thinks the program is greatly underfunded given the scope of the pest problem.
Found Avocado Lace Bugs On Your Tree?
1. Plant flowers around your trees. This attracts beneficial insects that eat the avocado lace bug.
2. A diluted mixture of rosemary oil, peppermint oil and water sprayed on the underside of leaves is an affordable, soft insecticide. But make sure you purchase your oils at a home gardening store because otherwise they could damage your tree.
3. Neem oil has also been shown to help the spread of bugs, but just like the essential oil mixture, make sure it’s formulated for gardening and you spray the underside of the leaves.
4. Don’t panic! While your tree may drop all its leaves and appear dead, continue caring for it and it’s likely to bounce back.
“The sad thing is the department has been not only underfunded but understaffed,” he said.
That’s not to say there haven’t been successes. Uyeda is currently working on a program on Kauai to help cabbage farmers fight the devastating diamondback moth. Planting Virginia pepperweed in their fields can attract bugs that eat the harmful moths.
Uyeda agrees that more support is needed to inspect imports, enforce quarantine and move quickly before infestations can spread. But he also stressed the importance of educating people on why there are restrictions on transporting plant materials between islands.
“This can really be detrimental to our commercial agriculture industry, as well as the home garden plants that we have growing in our state,” he said. “It’s all our jobs to run out there and try to help isolate the pest pressure.”
Experts say washing shoes with a bleach solution after hiking and never transporting plant material interisland are two easy ways to stop the spread of invasive species in Hawaii. Asking people to change their eating habits is a bigger task.
“It’s hard to tell people not to eat avocados,” said Caroll. He advises people to buy local fruit whenever possible, even if this means skipping your favorites when they’re not in-season.
Caroll hopes one day it’ll be easy to buy local avocados year-round, but there needs to be a lot more avocado farmers to meet the demand. He hopes scary headlines about the avocado lace bug doesn’t deter other farmers from planting avocados, but said there may be a silver lining if it helps people understand the risks of relying heavily on imports.
“Anytime we import food … there’s a cost in addition to what you pay at the store. When we’re buying Hass avocados from the store, we’re also paying for the cost of importing these bugs, importing these diseases,” he said. “We’re very thankful this wasn’t Laura Wilt disease because it would be the end of the avocado industry.”
“Hawaii Grown” is funded in part by grants from the Ulupono Fund at the Hawaii Community Foundation, the Marisla Fund at the Hawaii Community Foundation, and the Frost Family Foundation.
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