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United States Department of Agriculture

Agricultural Research Service

Research Project: DOMESTIC, EXOTIC, AND EMERGING DISEASES OF CITRUS, VEGETABLES, AND ORNAMENTALS (DEED) Title: Citrus Canker and Citrus Huanglongbing, Two Exotic Bacterial Diseases Threatening the Citrus Industries of the Western Hemisphere

Author
item Gottwald, Timothy

Submitted to: Outlooks on Pest Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 24, 2007
Publication Date: December 1, 2007
Citation: Gottwald, T.R. 2007. Citrus Canker and Citrus Huanglongbing, Two Exotic Bacterial Diseases Threatening the Citrus Industries of the Western Hemisphere. Outlooks on Pest Management. 18(6):274-9.

Interpretive Summary: Citrus canker and citrus greening known in Chinese as Huanglongbing (HLB) are two very serious diseases facing the citrus industries in the western hemisphere. Both Brazil and Florida are battling both diseases simultaneously and the presence of these diseases in these locations threatens other citrus producing areas and states, especially Californai and Texas. For citrus canker, the USDA, APHIS has proposed rules to attempt to keep the disease out of other citrus producing states in the US and to avoid shipping infected fruit to European and other concerned countries. Control of both diseases is difficult but somewhat easier for citrus canker. For citrus greening, adequate control has not been achieved anywhere in the world to date, a fact that greatly concerns US citrus producing states since it is now in Florida. Where partial control of greening has been achieved, it has been done by rapid removal of diseased trees and insect sprays to inhibit the buildup of population of the insect vectors that spreads it. This review-type article discusses control and the prospect of incorporating resistance to the disease into commercial citrus cultivars in the future.

Technical Abstract: Two exotic Asian bacterial diseases of citrus are currently plaguing citrus industries in the Western Hemisphere. The two largest citrus producing areas in the Americas, located in Florida and the state of São Paulo Brazil, are presently battling these devastating diseases. The presence of these diseases in the Florida and São Paulo citrus industries also pose an imminent threat to other major citrus producing areas within the US, such as California, Texas, and Arizona and citrus producing areas near São Paulo such as the state of Parana, Brazil and the important northern citrus producing areas in Argentina. The history, etiology, and symptomology of each disease are covered in detail as are the USDA, APHIS Pest Risk Assessment and Risk Management Analysis of canker and the implications and impact of future decisions on marketing. Control strategies are discussed which for canker involves windbreaks and copper sprays and for HLB is centered around infected-tree removals and psyllid-vector chemical control strategies. O particular concern is the observation that there is nowhere in the world where HLB is under adequate control, and where it does occur, it continues to increase in incidence and severity. On absolute recommendation is that the commercial citrus industry must collectively secure budwood and nursery operations to prevent propagation and spread of the disease. The difficulty of managing HLB is discussed and the prospect of future resistance to the disease.

Last Modified: 10/23/2014
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