If you want to suppress the spread of the Asian citrus psyllid, you start with the roots.
At least that’s what the California Department of Food and Agriculture is pushing onto communities in the state where the teeny tiny bug has been found. In SLO County, lemon, orange, grapefruit, and tangerine trees on 3,000 properties in Nipomo, Cayucos, Arroyo Grande, and San Luis Obispo have been treated.
Drenching the soil around the base of citrus trees with imidacloprid causes the pesticide to become systemic: absorbed like water, eventually becoming one with leaves, branches, and the fruit. As the psyllids feed off tree leaves, they absorb the chemical.
At the moment, it’s all we’ve got to battle this pest that has the potential to severely cripple California’s $2 billion-plus citrus industry. The psyllid is a carrier for huanglongbing, also known as citrus greening disease, which all but destroyed Florida’s booming citrus industry. And while imidacloprid doesn’t completely demolish psyllid populations, it helps keep them at bay when used in conjunction with spray-on pesticides. A recent U.S. Environmental Protection Agency (EPA) risk assessment of the chemical—which is one of four neonicotinoid-based pesticides being reassessed by the EPA—finds that using the chemical on crops could adversely affect pollinators, especially bees.
“It definitely shows us that there is a problem with bees and specific crops,” said Charlotte Fadipe with the California Department of Pesticide Regulation, an agency that helped perform the assessment. “Citrus and cotton in particular are problematic.”
The pesticide is already banned in several European countries, and although scientific studies, including a 2012 Harvard study, have linked imidacloprid with bee die-offs, Fadipe said the EPA didn’t have the studies it needed to regulate the pesticide. So the EPA assessed imidacloprid’s use on different crops, such as corn, potatoes, rice, citrus, and grapes, testing the pollen and nectar for residue and how much of the chemical was found in colonies, larvae, and the bees themselves.
The risk assessment was preliminary and released in January for public comment, which runs through February. Fadipe said there isn’t a set date for new regulations associated with imidacloprid or a thought as to what they would be, but “if I were a grower who uses imidacloprid, I would get ready for some regulations coming out as a result.”
However, the EPA “temporarily halted the approval of new outdoor neonicotinoid pesticide uses,” until the risk assessments are completed (December 2016), according to a press release from the agency.
Steve Lyle, a spokesperson from the California Department of Food and Agriculture, said the department would continue using imidacloprid in its programs.
“Citrus health and pollinators can each be protected, and protecting pollinators is a high priority. This is achieved by not treating when pollinators are present and not scheduling treatments when citrus plants are blooming,” Lyle said in an email to New Times.
So, controlling the psyllid will continue as usual, which is a good thing, according to Bill Coy, who’s been growing oranges for 35 years on his ranch in Cayucos—Rancho Rio Conejo. He said if the psyllid starts spreading huanglongbing, “citrus will be a thing of history.”
“The psyllid has to be controlled somehow. … So what are you going to do?” Coy said. “All these guys are trying to do is control that pest. That’s all they’re trying to do.”
Coy doesn’t use imidacloprid on his trees, and thus far hasn’t had any issues with the psyllid. But because his ranch is considered to be in the quarantine area, Coy said he does spray his trees with a non-neonicotinoid pesticide called Delegate a few weeks before harvesting the fruit.
He said of everything he’s looked at, Delegate is the least harmful to beneficial insects. That’s important because every year, beekeepers take their hives to Coy’s ranch to spend the winter.
And while beekeepers in Santa Barbara County are sounding the alarm about imidacloprid, those in San Luis Obispo County have remained relatively silent, according to SLO County Agricultural Commissioner Martin Settevendemie. The commissioner’s office works closely with the Department of Food and Agriculture on the county’s psyllid program.
When a psyllid is found, every citrus tree within a 400-meter radius is targeted with the combination of pesticides. And the vast majority of those trees have been in residential areas.
Settevendemie said the county has about 20 registered beekeepers, and his office hasn’t received any word of bee die-off due to imidacloprid. He added that several California beekeepers choose to winter their bees in SLO County, while renting them out to Central Valley almond growers in the spring and summer.
Jeremy Rose, a Central Coast beekeeper based in Santa Maria who owns the California Bee Company, said he wouldn’t be taking his bees to the Central Valley again anytime soon.
Last year, his hives suffered a direct hit from a fungicide applied to an almond grove that killed off $50,000 worth of bees. Because of widespread pesticide use on farms and in residential areas, Rose chooses to stick his hives in the woods.
“Everything kills them, and there’s nothing I can do about it, except take my bees out into the forest,” Rose said. “There’s always a new pesticide, so I don’t see what the big deal is [with the imidacloprid assessment].”
Contact Editor Camillia Lanham at firstname.lastname@example.org.