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.”

Beet Curly Top Virus Alert for Growers

BCTV Grower Alert

by Laurie Greene, California Ag Today reporter

California Department of Food and Agriculture’s Beet Curly Top Virus Control Program (BCTVCP) personnel observed very high sugar beet leafhopper (BLH) counts the first week of March. BLH were mostly nymphs between the 2nd and 4th instar (a developmental stage of  insects, between each moult) with few spring adults.  BLH counts averaged 30-50 adults and nymphs per 10 sweeps. In some locations, counts have been as high as 100 BLH per 10 sweeps. A “normal” spring count would be an average of 10-12 adult BLH and 5-6 nymphs per 10 sweeps. These current conditions follow a devastating year for BCTV in California crops.

Treatment is currently focused on Fresno and Kings Counties where BLH populations are high. BLH counts are minimal at this time in Kern, San Joaquin, and Stanislaus Counties.

Treatment preparations were made last week and the spring treatment campaign began on March 9, 2015. The spray campaign will face several challenges, such as, wind, rain, and heat.  However, the Program is exploring all available options to treat as much of the population as possible. The Program has identified a total of 54,974 acres to be treated so far.

The BCTBCP’s objective is to reduce the incidence of beet curly top virus (BCTV) infection in susceptible crops below a level of economic importance, through the use of integrated pest management techniques. BCTV is an extremely serious plant virus affecting several hundred varieties of ornamental and commercial crops in California. The Curly Top Virus Control Board advises the Secretary on this Program.

The only known vector of this virus the BLH  is an introduced pest and migratory by nature. Populations develop in selected habitats within the San Joaquin, Imperial, Sacramento and Intra coastal Valleys of California as well as moving into California from contiguous states and Mexico. The BCTVCP utilizes intensive surveys to locate and monitor BLH populations throughout the year. As much as 100,000 acres of rangeland and idle agricultural lands are treated annually to control breeding BNL populations on a variety of host plants prior to the migration of adult leafhoppers into susceptible crops. Winter, spring and fall treatment periods coincide with the reproductive biology of BLH. The Program has emphasized the use of biological control by funding research in the exploration and establishment of BLH egg parasites in California.

Just last month, BCTVCP issued the following alert:

The Beet Curly Top Virus Control Program would like to remind growers to disk weedy areas as (soon as possible) prior to the 2015 tomato season. Good weed management prior to having tomatoes transplanted is ideal. When possible, sweep surveys should be conducted to identify the beet leafhopper is present and then an insecticide should be applied prior to disking the weeds. Mowing and disking weedy areas disturbs the beet leafhopper causing it to relocate to other suitable habitat. Although tomato plants are not an ideal host for beet leafhoppers, the leafhoppers will filter through tomato fields, transferring the curly top virus, while they are in the process of looking for another suitable host. The Program also encourages growers to get to know their neighbors and relay the message of good weed management.