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Asian Citrus Psyllid and Huanglongbing Management in California: How Psyllid Spread Will Affect Costs Karen M. Jetter 1 , Elizabeth E. Grafton-Cardwell 2 , Matthew P. Daugherty 2 , and Robert Johnson 3 1 UC Agricultural Issues Center 2 Dept of Entomology, UC Riverside 3 Kearney Agricultural Research and Extension Center The ASIAN CITRUS PSYLLID The Asian Citrus Psyllid (ACP) is a new pest of extreme economic importance in California. It arrived in residential areas in 2008, and by 2012 it established in commercial production areas of Riverside, Coachella, Imperial and San Diego. In 2013 ACP was found in commercial groves in Ventura County and a handful of locations in the southern San Joaquin Valley. It is currently found at varying levels in all major commercial citrus producing counties in California. ACP MANAGEMENT CITRUS IN CALIFORNIA California is a top producer of citrus in the U.S. and the top producer of fresh market fruit. In 2013, acreage planted in all citrus was 277 thousand and total value was over $2.5 billion. Oranges are the most valuable crop. By value, mandarins are the next largest crop, followed closely by lemons, and finally by grapefruit. Asian Citrus Psyllid 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000 2011 2012 2013 2014 Number of sites treated Number 0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000 180,000 200,000 2011 2012 2013 2014 Total Cost Dollars Ventura Eradication Program: Residential Costs HLB Damaged Citrus x Current locations of ACP, HLB and citrus in California Crop Acreage Production (tons) Value ($ milions) Grapefruit 11,050 160,490 85 Lemons 45,209 745,034 565 Oranges 173,661 2,442,147 1,359 Tangerines and Mandarins 47,283 420,540 567 Total 277,203 3,768,211 2,576 WHY ACP & HLB ARE IMPORTANT The ACP can transmit a bacterium that causes the disease known as Huanglongbing (HLB) or citrus greening. This disease renders fruit mishappen and bitter tasting. Over time, because there is no known treatment for HLB, the disease eventually causes tree death. As a vector of the pathogen associated with HLB, spread of this insect puts at risk the state's 2 billion dollar citrus industry wherever ACP establishes. Management of ACP and infected tree removal are the only known methods of limiting the spread of HLB. The challenge with using tree removal to control HLB is that there can be a long latency period between when the tree first becomes infected and when it can transmit the disease. During this time, ACP will continue to feed on the diseased trees and spread the disease to new trees. EXAMPLE: VENTURA ACP ERADICATION PROGRAM The Asian Citrus Psyllid (ACP) was first identified on sticky cards in 2010 in Ventura County. Two finds (in orange below) were made in 2010 and four in 2011 (in brown). In 2012 36 ACP populations were discovered. All finds over the years were treated with the eradication protocol. In 2013 and 2014 the number of finds dramatically increased, and eradication boundaries started to overlap. Finds were still treated using the eradication protocol. Some sites needed more than one treatment. Ventura Residential Program The eradication program in Ventura in residential areas reached its peak in 2013. In 2014, CDFA stopped treating every trap find in the residential areas and started to focus its treatments in neighborhoods that bordered commercial groves. Total costs to treat ACP in residential neighborhoods from 2011 through 2014 was $392 thousand, paid by growers through their assessment by the Citrus Pest and Disease Prevention Program. 0 2,000,000 4,000,000 6,000,000 8,000,000 10,000,000 12,000,000 2011 2012 2013 2014 Acres Treated Lemon Other citrus $3.5 million $3.8 million $7.9 million $10 million Ventura Commercial Program The eradication program in Ventura in commercial orchards increased dramatically in 2013 and 2014 in response to the expanding ACP population. For lemons (the principle citrus crop in Ventura County) there was a 161% increase in insecticides expenditures from 2010/2011 to 2014. For all other citrus this increase was 200%. Ventura Eradication Program: Grower Costs WHERE DID THE BIGGEST PERCENT CHANGES IN INSECTICIDE USAGE OCCUR? ACP MANAGEMENT – ERADICATION STRATEGY Effective control of ACP is crucial for preventing the spread of this deadly disease. The first line of defense in ACP management would be to eradicate small outbreaks to delay the moment when ACP would become established. The eradication programs consists of the California Department of Food and Agriculture (funded by grower associations) treating citrus with two insecticides when ACP is found in residential areas. When ACP is found in commercial citrus, the grower conducts an eradication program consisting of the use of a systemic neonicotinoid and a foliar pyrethrioid where systemic insecticides are effective, or one spray with a pyrethroid and another foliar spray in a different chemical class. These programs can have significant costs, but are a fraction of the annual value of production if trees are lost to HLB. Crop Pyrethroids Neonicotinoids Organics (Pyrethrins and Entrust) Lemons 3,741% 481% 146% Other Citrus 981% 144% These materials rarely used before ACP WHAT ARE GROWERS IN VENTURA COUNTY DOING NOW? There is still an eradication program in select areas; however the county is moving to areawide ACP management in most areas. The areawide management program will be evaluated next to assist growers with decision making with regards to ACP control.
