HONOLULU CIVIL BEAT - One day in March, Big Island avocado farmer David Cox discovered colonies of tiny, black bugs on some of the trees in his orchard.
About the size of a pin prick, the voracious insects were stuck to the underside of the leaves, sucking up a meal of green chlorophyll.
Soon, leaves on the infested trees turned yellow, then brown. Some trees lost their leaf cover completely, leaving the prized fruit overexposed to a harsh and potentially damaging Hawaiian sun.
It had been only about four months since the pest first appeared on Cox’s farm when he declared it had spread to all 550 trees in his orchard, covering the underside of every visible leaf.
“It was just devastating,” said Cox, whose 27-acre Kane Plantation in Honaunau hosts the state’s only certified avocado-packing house that exports about 120,000 pounds of fruit per year to the mainland. “There was massive damage. I’ve never seen, in 10 years, trees in such poor condition.”
The avocado lace bug, an invasive pest from the Caribbean, arrived in the U.S. in Florida more than a century ago and has since appeared in California, Georgia, Texas and, most recently, Hawaii in 2019.
The bug weakens, but does not kill, avocado trees, attacking the leaves that protect the fruit from developing rust-colored sun blotches. These blemishes can reduce the fruit’s market value and lower farmers’ profits.
For Hawaii’s farmers, unattractive fruit nearly always translates to financial losses that stand to threaten a $3 million dollar avocado industry at a time when the state is angling to boost local food production.
Cox’s experience is not unique.
Scores of avocado growers on Oahu, Maui and the Big Island say they are battling the pest for the first time this year following the discovery of a heavy infestation of avocado lace bug at the Oahu Urban Garden Center in Pearl City in December 2019. There are so far no official reports of avocado lace bug on Kauai, Molokai or Lanai.
“I probably get 50 emails or calls a week,” said Ken Love, executive director of Hawaii Tropical Fruit Growers. “Even on our Facebook page we’ll get 10 posts and photos a week saying, ‘What’s going on? What’s wrong with my avocados?’ If they scrolled down they would see the question five, 10 other times. People just don’t know what’s going on.”
Although it’s still early in avocado season and the full impact of the pest remains unseen, farmers say they are bracing for reduced yields, smaller fruit size and an increase in blemished, off-grade fruit that can’t be sold.
“Many of us don’t know what to do other than just wait and see what happens,” said Cox, who is the vice president of the Hawaii Avocado Association. “Will nature correct this sudden infestation somehow or balance it so that it’s manageable? How long is it going to last?”
Although the pest can quickly mar a beautiful avocado tree into a cosmetic nightmare, some experts say the emergence of avocado lace bug in Hawaii may not be a major issue. At least not compared to problems like coffee leaf rust, a devastating, relatively new disease detected on all the major islands that can cause coffee trees to die.
Mark Wright, an expert in pest management for tropical fruit and nuts at the University of Hawaii’s College of Tropical Agriculture and Human Resources, said the presence of the bug in California and Florida has not so far triggered any significant economic losses for avocado farmers — a good sign for Hawaii growers.
“It looks terrible for the tree,” Wright said. “But the impacts are probably way less severe than people are expecting.”
Light and moderate avocado lace bug infestations will not cause severe long-term damage to trees and therefore do not require management, according to Wright, but dense infestations causing dramatic leaf damage can be managed with organic or conventional pesticides.
But the cost of doing so can be prohibitive.
“On my farm, it works out to about $3.50 per tree, plus about five minutes, to apply the spray,” said Cox, whose avocados are certified organic. “Times that by my 550 trees, and then you have to do three rounds of spraying every couple of weeks, and it comes in close to $10,000. That’s the entire year’s profit gone and you haven’t even gotten rid of the problem because it’s just going to come back.”
One possible solution being explored by federal and state researchers is identifying a naturally occurring predator insect and using it to suppress avocado lace bug populations in Hawaii’s avocado orchards.
In the Caribbean, for example, there are two naturally occurring biocontrol species that prey on the pest, helping to keep infestations in check.
In the islands, one such natural enemy may be the lacewing, an insect known to protect numerous crops from pests.
Mark Hoddle, a biological control specialist who studies avocado lace bug at the University of California at Riverside, said the insect appears to be more aggressive in tropical climates like Hawaii.
In sticky, humid conditions in the Caribbean, the avocado lace bug seems to cause more damage than it does at cooler temperatures, such as high-elevation avocado farms on the sides of Guatemalan volcanoes, he said.
Nuances in California’s history of avocado lace bug infestations suggest there could be value in determining the unknown origin of Hawaii’s pest.
In California, the avocado lace bug was discovered in 2004 on backyard trees in San Diego County. DNA testing suggests the pest originated from Mexico, according to Hoddle.
Oddly, the infestations fizzled out. The pest was not seen in the state again for another 13 years, when reports of the avocado lace bug cropped up in 2017 in the Los Angeles area, Hoddle said.
This time, the damage was worse. The origin of the bugs in the secondary wave of California infestations appears to be Mexico.
Now, the pest seems to be everywhere in California, Hoddle said.
About six weeks ago Hoddle received a shipment of dead avocado lace bugs from Hawaii. His team is performing DNA tests to determine the pest’s origin, which could offer clues about how destructive the bug will turn out to be in the islands.
“It’s another pest that we don’t want,” Hoddle said. “Obviously the trees look ugly. It stresses people out. And it’s probably going to lead to more insecticide use because growers don’t want to see big brown splotches on their leaves.”
Meanwhile, local farmers say the pest presents a hindrance to efforts to grow the state’s avocado production. Hawaii produces about 610 tons of avocados annually, amounting to less than 1% of the total U.S. tonnage.
“We’re just a fledgling industry,” said Brooks Wakefield, a Hawaii Avocado Association board member. “We’re trying to get more and more people to plant and grow avocado since we need more in our state. We import so much, so we’re trying to get people excited about it and it was such an easy crop to grow. That’s why this is really devastating.”