Reducing ACP Spread In California

Beth Grafton-Cardwell: Spread of Disease Must Be Prevented

By Patrick Cavanaugh, Editor

Collaborative changes are being made to combat the Asian Citrus Psyllid (ACP). Beth Grafton-Cardwell is the director of Lindcove Research and Extension Center near Exeter, as well as a research entomologist with UC Riverside. She recently spoke at the 2019 Citrus Showcase in Visalia as a key speaker on the state of Huanglongbing (HLB) in California, with an overview of how to prevent ACP,—which vectors HLB, a fatal disease to citrus—from moving around the state.

We were trying to communicate why we’ve made the changes we’ve made for the industry that has been a collaborative effort between CDFA, growers, and the university, Grafton-Cardwell said. “We need better ways to prevent psyllids from moving around the state because they might have HLB in their bodies, and we’ve got to prevent the spread of the disease.

beth_grafton-cardwell
Beth Grafton-Cardwell

The Florida citrus industry did not do a great job in containing the Psyllid, and now HLB is rampant in the state’s citrus industry, which has devastated the citrus economy there.

“Florida found that they did not do much to control psyllid movement, and they found that psyllids were moving in bulk citrus bins and retail nursery plants around the state, and within a concise amount of time, they spread the Psyllid and the disease everywhere,” Grafton-Cardwell said. “We’re trying to avoid that. We have 100% tarping of citrus truckloads. We have treatments that have to be done if growers want to move citrus between major zones in California, so that we can prevent that kind of movement.”

Conversations continue about quarantine areas in California to reduce spread.

“There’s been a lot of discussion regarding quarantines because it’s painful for some growers who have low Psyllid numbers to have to treat and to move their fruit to other zones.”

“There’s been a lot of questions. We did a lot of scientific analysis to look at impacts as well as numbers. It’s not just about psyllid numbers; it’s about their impact if growers were to move the disease into a high citrus growing region,” Grafton-Cardwell explained.

Quarantines in Place to Prevent ACP Spread

Quarantines Painful For Some Growers

By Mikenzi Meyers, Associate Editor

It’s been a tough road for citrus growers since the discovery of the Asian Citrus Psyllid (ACP) back in 2012. Those affected have been forced to quarantine their crops, a task that Beth Grafton-Cardwell, director of Lindcove Research Extension Center in Tulare and research entomologist with UC Riverdale, said can be difficult.

“There’s been a lot of discussion about the quarantines because they’ve been painful for some growers who have low psyllid numbers to have to treat them and move their fruit to other zones,” Cardwell explained.

Beth Grafton-Cardwell

The growing concerns have led to continuous research regarding whether or not the zones should be changed.

There have been more than 1,100 citrus trees that have tested positive for HLB. There have been more than 230 positive finds of the psyllid, and although this sounds like a big number, Cardwell said its actually normal due to how difficult the disease is to detect.

“We can’t tell that the tree is infected early on because a localized infection might be on one stem of the entire tree, and it might take a year before it moves throughout the tree,” she said.

Right now, quadrant sampling is being done, where four quadrants of the tree are sampled for the disease. Current samples are showing that one in four quadrants are coming back positive.

“It’s finding the trees that are infected that’s really difficult, and meanwhile, the psyllid is spreading, spreading, spreading the disease,” Cardwell said.

 

More information can be found at this link:

https://maps.cdfa.ca.gov/WeeklyACPMaps/HLBWeb/HLB_Treatments.pdf

Fighting Asian Citrus Psyllid On and Off the Farm

Fighting ACP on Farms and Residential Areas Critical

By Hannah Young, Associate Editor

Pests and diseases are as prominent as ever not only for California farmers but in residential areas as well. California Ag Today recently spoke with Rick Westcott, a senior sales rep for Bayer Crop Science, about preventative materials for pests and diseases and the importance of controlling the spread of those diseases, particularly Asian citrus psyllid.

Westcott explained that the advantage of Movento, a powerful insecticide, is that it is systemic, it’s applied early, and it will translocate throughout the entire tree.

“It’s both phloem and xylem movement, so it’ll go down into the roots and then back up so it constantly recirculates within the plant,” Westcott said. “That’s what gives it the longevity of control.”

In citrus trees, Movento typically takes about 65 to 70 days to start working after circulating through the plant which helps with the longevity of the product, Westcott added.

Although Movento is not used specifically for Asian citrus psyllid, it has proved to aid in controlling the pest.

Westcott said Movento is currently being used against citrus red scale and applied during pedal fall along with thrip sprays, which farmers are applying anyway.

“It will take care of your red scale, your early red scale spray, and of course, because it also controls Asian citrus psyllid, it’s a bonus to do that too,” Westcott said. “Then the other thing that they’re doing with the thrip spray as well for katydid control, which is also an issue in citrus at that thrip timing.”

By patrolling and monitoring for ACP, the spread of HLB can also be controlled.

“The key is to keep the ACP at the lowest level possible or zero if that’s possible. [The] fortunate thing for us in the San Joaquin Valley is the fact that we do a lot of spraying for other pests throughout the year that almost everything that we put in the tank happens to also control ACP at the same time,” Westcott explained.

Westcott said that this is the reason we have not seen a huge outbreak of ACP in the San Joaquin Valley, unlike other parts of California.

“The problem isn’t in any commercial grove at this point, but it’s all residential,” Westcott continued. “It’s all concentrated in the residential areas, so there are certain products that you can use an ag that you can’t use there, but most of them, fortunately, you know, they have a label for both residential and agriculture, so they do crossover to stop them there so they don’t get here.”

HLB is still posing a threat in California, but most specifically in the Los Angeles area.

“The total amount of trees currently that are infective with HLB in the counties of LA, Orange and Riverside County is 645. And then if you compare that from a year ago: a year ago, there were only 73 trees that they had infected, and it’s changing every day,” Westcott said.

Research Nets Going Over Citrus Trees To Prevent Huanglongbing Disease

Blocking Psyllids Carrying Disease is Key

By Jessica Theisman, Associate Editor

Beth Grafton-Cardwell is the director of the Lindcove Research Extension Center in Tulare County and research entomologist based out of the University of California, Riverside. She recently told California Ag Today that there is work being done on installing a net structure to protect trees from Asian Citrus Psyllids, which spread the deadly Huanglongbing disease. Texas A&M researchers are installing net structures on the edge of groves to block psyllids from coming into an orchard.

Psyllids have a preference for borders. These nets could have yellow sticky strips of material with an insecticide on it, so there would be an attract and kill process.

Beth Grafton-Cardwell

Other research is looking at netted structures that will completely enclose the citrus trees.

“Researchers are going to construct a completely enclosed net structure to grow the citrus trees in a block at Lindcove,” Grafton-Cardwell said. “We will study how well one can grow citrus under the screen so there could be the ultimate protection against pests and diseases.”

“The mother trees and increased trees have to be grown under the screen, but the field trees do not necessarily have to be,” she said.

Cold temperatures in the winter to protect the citrus from the psyllid.

“The cold temperatures hardened off the tissue, which makes it hard for the psyllid to find any place to lay eggs, and they probably cost some mortality to the psyllid,” Grafton-Cardwell explained.

Most outbreaks are in Southern California. Los Angeles, Orange County, and a few trees in Riverside.

“Prevention is working and there are fewer outbreaks in the Central Valley,” Grafton-Cardwell said.

Dr. Mark Hoddle and Dr. Kelsey Schall (both from UC Riverside) have been monitoring backyard situations. They are researching the release of beneficials such Tamarixia and other generalist predators like Syrphid flies.

“They have been reducing psyllids by about 70 percent in the backyards, and that’s really good news,” Grafton-Cardwell said.

UPDATE: ACP Quarantine and Advocacy for Unimpeded Eradication

by Laurie Greene, Editor

CDFA filed a proposed emergency amendment TODAY to expand the ACP quarantine area in response to an “infestation” of the Asian citrus psyllid (ACP), Diaphorina citri, detected in the Farmersville/Visalia area (June 4, 2014), Tulare County. One adult female was found in the area. The proposed 14-mile expansion will include the Visalia area, and the state’s vast ACP quarantine will cover 46,544 sq. miles.

CDFA Secretary Karen Ross
CDFA Secretary Karen Ross

The regulation defines emergency as” a situation that calls for immediate action to avoid serious harm to the public peace, health, safety, or general welfare.” The government code provides,”if the emergency situation clearly poses such an immediate, serious harm that delaying action to allow public comment would be inconsistent with the public interest, an agency is not required to provide notice.”

CDFA Secretary Karen Ross believes that this emergency clearly poses such an immediate, serious harm that delaying action to give the notice would be inconsistent with the public interest. Therefore, Ross proposed that the CDFA Director may adopt reasonably necessary measures such as bypassing the mandatory notice five working days prior to emergency action in order to carry out emergency provisions. Additionally, she requested that the Director be permitted to establish, maintain, and enforce quarantine, eradication, and such other regulations necessary to circumscribe and exterminate or prevent the spread of any pest which is described in the code.

This comes after the California Citrus Industry’s recent backlash against the Executive Committee of the California Citrus Pest and Disease Prevention Committee’s proposed easing of the state’s ACP quarantine and eradication efforts.

Joel Nelsen, CA Citrus Mutual President
Joel Nelsen, CA Citrus Mutual President

And, while CDFA uses the word, “infestation”, Joel Nelsen, President of California Citrus Mutual, commented at the recent United Fresh Convention in Chicago, “There were two more ACP finds found in the northeast part of Tulare County. They were individual finds. Intensive trapping and tapping on the trees, looking for the ACP, hasn’t found any more. So one would argue that we’ve got a population—given the finds in the last year—but we’re still talking single digits.” Nelsen believes this demonstrates the eradication programs are working. “We’re supposed to find the ACP before finds a commercial citrus industry, and we’re doing that.”

Nelsen said the Executive Committee’s recent proposal to significantly modify the program was, “based upon some subjective analysis by a team of scientists who in fact believe that there’s more out there than what we can find.”

“So,” he continued, “we’re obligated to prove a negative; and as long as we do the intensive trapping program, as long as we continue the mandated treatment program, as long as we’re aggressively looking for the Asian citrus psyllid—I don’t see how, and industry doesn’t buy into the fact, you have an endemic population. We’re not finding them in volume; everything is isolated.”

“So, when the industry first became aware of this possible change in the treatment zones of the quarantine mandates, the industry challenged CDFA.”

Now, not only does the ACP program remain intact, but TODAY, CDFA Secretary Ross proposed measures for an unhindered and  immediate eradication response by CDFA to ACP discoveries.

Featured Photo Credit: Ted Batkin, Citrus Research Board, “Invasive Pests in California” 1/10.