Preventing the Spread of ACP

Valley Citrus Growers Continue Vigilance

By Jessica Theisman, Associate Editor
ACP
USDA ACP Cooperative Program Map (Source:
California Citrus Pest & Disease Prevention Program)

The spread of Asian Citrus Psyllid (ACP) continues to be a looming threat for Central Valley citrus growers as it vectors Huanglongbing (HLB), a disease that destroys citrus trees. Greg Douhan, a University of California Cooperative Extension Tulare County citrus farm advisor reported to California Ag Today recently that, “There have been so many people onboard really working at this from multiple angles, and we’re in the eradication mode. We want to make sure the insect doesn’t get established in the San Joaquin Valley.”

“If one were to look at a map of ACP infestation in California [such as CDFA Quarantine Maps and California Citrus Pest & Disease Prevention Program Threat map], they may consider it to be endemic in the Los Angeles area. Rest assured that anytime ACP is found in a trap, the CDFA sprays everything in that area within 400 meters.”

Douhan said the Valley is on high alert to find ACP in traps. “

If researchers discover a cluster of finds in any particular area, we manage some spray programs and try to get all the growers to do a coordinated effort in order to try to combat it,” he said.

SaveOurCitrusIn addition, the SAVE OUR CITRUS app is a free USDA iPhone app to report and identify the four leading citrus diseases: citrus greening, citrus canker, citrus black spot and sweet orange scab. Report your symptoms, upload a photo, and citrus experts will respond.

So far, the practices have been working well.

“I think most of the growers are very well informed,” Douhan said, “and are taking this very seriously because it is this their livelihood.”

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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.

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ACP Spread in Bakersfield Area, Ingenious Research Proceeds

Ingenious Research Effort to Fight ACP Spread with Natural Predators

 

By Joanne Lui, Associate Editor

 

beth_grafton-cardwell
Beth Grafton-Cardwell, Cooperative Extension specialist, University of California, Riverside Department of Entomology

As we have reported in-depth before on California Ag Today, the Asian Citrus Psyllid (ACP) is a tiny, mottled brown insect that poses an ever-increasing threat to the state’s robust citrus industry, as well as to residential citrus trees. The pest can spread a bacterium known as Huanglongbing (HLP) that is fatal to citrus trees. The disease has nearly shut down Florida’s citrus industry.

Beth Grafton-Cardwell, cooperative extension specialist in integrated pest management, UC Riverside Department of Entomology, explained the significance of the recent ACP spread to Bakersfield. “That is really problematic because it’s mostly in the urban areas. It’s very difficult to find, to control and to stop that spread. It’s going to move out from that region into the local citrus orchards, and so there are lots of meetings and discussions right now to mobilize growers to get treatments to help protect their citrus orchards against the psyllid.”

#CitrusMatters
#CitrusMatters

To contain the ACP problem, Grafton-Cardwell stated, “There are traps everywhere, but the traps are not terribly efficient. So, we really need to carefully examine groves and flush [new leaf growth] for the nymph form,” she said.

According to Agriculture and Natural Resources, University of California’s Statewide Integrated Pest Management Program:

Adults typically live one to two months. Females lay tiny yellow-orange almond-shaped eggs in the folds of the newly developing “feather flush” leaves of citrus. Each female can lay several hundred eggs during her lifespan.

ACP UC IPM
ACP (Source: ACP UC IPM)

The eggs hatch into nymphs that are wingless, flattened, yellow or orange to brownish, and 1/100 to 1/14 inch long. Nymphs molt four times, increasing in size with each nymphal stage (instar), before maturing into adult psyllids. The nymphs can feed only on soft, young leaf tissue and are found on immature leaves and stems of flush growth on citrus.

Save Our CitrusThe nymphs remove sap from plant tissue when they feed and excrete a large quantity of sugary liquid (honeydew). Each nymph also produces a waxy tubule from its rear end to help clear the sugary waste product away from its body. The tubule’s shape—a curly tube with a bulb at the end—is unique to the Asian citrus psyllid and can be used to identify the insect.

Grafton-Cardwell and other experts are concerned because once the ACP becomes established in urban areas, it is difficult to eradicate. “It starts spreading into the commercial citrus, and we’re off and running,” she commented.

bayer-save-our-citrusIn a ingenious effort to control the spread of the psyllid, trained teams of entomologists have imported Tamarixia radiata, a tiny wasp that naturally preys on ACP, from Pakistan to research and release in California. A cooperative effort of the University of California Riverside, Citrus Research Board, United States Department of Agriculture and California Department of Food and Agriculture, researchers are also exploring the effectiveness of another beneficial insect called Diaphorencyrtus aligarhensis to assist Tamarixia with control of the Asian citrus psyllid. To see where Tamarixia and Diaphorencyrtus have been released, visit this University of California’s website map at, “Distribution of ACP, HLB and Parasites in California,” and turn on the parasite layers.
Grafton-Cardwell said, “They’re going to inundate that area,” with natural ACP predators, “so hopefully that will push back a little bit.”

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