Asian Citrus Psyllid: California Round-Up
April 30, 2015 The march through California of the Asian citrus psyllid (ACP) continues. This invasive species is of grave concern because it can carry the disease huanglongbing (HLB), also known as citrus greening, which has no known cure.
Just over a month ago the pest was detected in the heart of the San Joaquin Valley, leading the California Department of Food and Agriculture to place another part of the state under quarantine.
An additional portion of Madera County was placed under quarantine following the detection of one psyllid east of the City of Madera, in the Bonadelle Ranchos area. The quarantine expansion adds 79 square miles, bringing the total quarantine area in Madera County to 179 square miles.
The 79 square mile expansion is bordered on the north by Avenue 15; on the south by Avenue 9; on the west by Main Canal; and on the east by State Highway 41. The quarantine prohibits the movement of citrus and curry tree nursery stock out of the quarantine area and requires that all citrus fruit be cleaned of leaves and stems prior to moving out of the quarantine area.
An exception may be made for nursery stock and budwood grown in USDA-approved structures that are designed to keep ACP and other insects out.
Residents with backyard citrus trees in the quarantine area are asked not to transport citrus fruit or leaves, potted citrus trees, or curry leaves from the quarantine area.
In addition to a portion of Madera County, ACP county-wide quarantines are now in place in Imperial, Los Angeles, Orange, Riverside, San Bernardino, San Diego, Santa Barbara, Tulare, and Ventura counties, with portions of Fresno, Kern, San Joaquin, San Luis Obispo, and Santa Clara counties also under quarantine.
All citrus and closely related species, such as curry trees, are susceptible hosts for both the insect and disease. There is no cure once a tree becomes infected. The diseased tree will decline in health and produce bitter, misshapen fruit until it dies.
On the bright side, HLB has been detected just once in California — in 2012 on a single residential property in Hacienda Heights, Los Angeles County.
Florida’s Experience
However, HLB, or citrus greening disease, is extremely deadly and has destroyed hundreds of thousands of acres of citrus in Florida. In fact, according to a poll taken last month in Florida, 90% of respondents said they thought the 2014-15 Florida orange count will fall below 100 million boxes, despite the fact that the April USDA 2014-15 all-orange outlook came in at 102 million boxes. That’s down from 242 million boxes in 2003-04, before the disease took hold.
Southern Gardens Citrus was one of two commercial growers to first identify HLB in its groves in October 2005. Ricke Kress, president of the company, told Florida Grower, a sister publication of Western Fruit Grower, that more than 800,000 infected trees have been removed from its groves since the find.
Like others, Southern Gardens is doing all of the cultural practices such as solid nutrition and aggressive psyllid control to stave off the disease as much as possible. The company is even experimenting with genetic modification, or GMO technology, despite fears on the part of some consumers.
“We put the first genetically modified trees in the ground in 2009 in controlled field trials,” Kress told Florida Grower. “All of these trees are planted and regulated as part of the federal government approval program. You don’t step out with any of this technology without concurrence of the federal and state agencies involved.”
Six generations of transgenic trees have been developed since 2009. With each generation, researchers refine the gene’s placement in the tree’s DNA to improve performance against HLB.
“We have a tree from our first generation that bore fruit this year,” Kress says. “Compared to control trees that are either stunted or dead, this tree is growing. It is showing a little infection, but it is growing. It is tolerant to HLB. It is a start.”
New California Program
Last month, California officials launched an education program for nurseries to control the spread of ACP.
The Sacramento-based Citrus Pest & Disease Prevention Program is a partnership including CDFA in conjunction with University of California Cooperative Extension and the Department of Entomology at the University of California-Riverside. It has established best practices and consumer education materials for retail nurseries.
The Citrus Pest & Disease Prevention Program will work with trade associations including the California Citrus Nursery Society, the California Association of Nurseries and Garden Centers and Master Nursery Garden Centers to distribute the information and offer in-person and online training programs.
In addition, California Citrus Mutual, in conjunction with Bayer CropScience, has launched a new campaign, #CitrusMatters, to publicize the battle against HLB. See “Effort Launched To Raise Consumer Awareness Of Deadly Citrus Disease.”
Consumers need to understand just how deadly HLB is, and how most experts agree that it’s just a matter of time until the ACP in the state begin spreading the incurable disease. That’s why a lot of scientists believe that the use of GMOs might be the only way to save the industry. ●
SIDEBAR: No Doubt About It — Citrus Matters
At California Citrus Mutual’s Citrus Showcase, Bayer CropScience and California Citrus Mutual announced #CitrusMatters, a year-long campaign geared at raising consumer awareness of the Huanglongbing (HLB) disease and the devastating impact it could pose to the state’s $2.4 billion citrus industry.
The campaign will utilize an educational website (CitrusMatters.US) and the hashtag #CitrusMatters in social media to educate California homeowners with citrus trees on their property about the important role they play in helping protect California citrus.
Given that an estimated 60% of California homeowners have citrus trees on their property, reducing the risk of infection from backyard trees to commercial citrus groves is vital to the health of the industry. In fact, most of the state’s citrus trees are not found in commercial groves, but in residential settings.
“Commercial citrus growers are already taking preventative action against HLB, but their groves will be threatened if the disease infects residential areas,” said Joel Nelsen, president of California Citrus Mutual.
“Our goal is to educate homeowners about the dangers of the disease and empower them to take action to help prevent the spread of HLB in California,” he said. “With the assistance of California residents, we can help protect the California citrus industry and the fresh fruit we all love.”
Through September, with every share of the #CitrusMatters hashtag, Bayer CropScience will donate $1, up to $25,000, to California Citrus Mutual in support of prevention, detection and research on this devastating disease.
Citrus growers are encouraged to join Bayer CropScience and California Citrus Mutual by sharing why #CitrusMatters with family, friends and neighbors who have citrus trees in their yards.
“We are committed to helping prevent the spread of HLB and preserve the livelihood of California’s professional citrus growers and the state’s citrus industry,” said Rob Schrick, horticulture strategic business lead, Bayer CropScience. “We’ve seen the impact HLB has had in other markets, and through #CitrusMatters, we hope to inform and engage Californians to help prevent a similar situation in their state.” ●
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