Managing Huanglongbing/Citrus Greening Disease. Issue Brief 4
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Subregional Office for the Caribbean ISSUE BRIEF #4 Managing Huanglongbing/Citrus Greening Disease in the Caribbean October 2013 KEY FACTS X Citrus Huanglongbing (HLB) or Citrus Greening Disease, caused by a bacterium (Candidatus Liberibacter asiaticus). X HLB is one of the most serious and devastating of all the diseases affecting citrus. Globally, HLB has destroyed more than 100 million trees. X In the Caribbean, Jamaica and Belize have been severely affected by the disease. FAO projects were implemented in both countries in 2011-2013 and have had some success in salvaging trees and increasing yields. Transboundary movement of plant diseases has always existed, presenting a constant threat and, in some instances, causing devastation to entire industries. But in an X A regional project for Latin increasingly globalized world with greater and more rapid flow of people and goods America and the Caribbean across borders, prevention of transboundary movement of diseases has become far was launched in November more difficult and requires the coordinated intervention of all stakeholders on national, 2012 and is establishing: regional and even international levels. – Standard Operating Procedures to One industry of great importance to several Latin American and Caribbean countries communicate risks, surveillance, is currently facing a potentially devastating disease. The regional citrus industry diagnostics and management provides products such as fresh limes, lemons, oranges, tangerines, grapefruit and other citrus as well concentrates and juices, contributing both to domestic – a Regional Information and food security as well as to foreign exchange earning via exports. The emerging Communication System threat comes in the form of Citrus Huanglongbing (HLB) or Citrus Greening Disease, caused by a bacterium (Candidatus Liberibacter asiaticus). – networking mechanisms among subregional plant health agencies HLB is one of the most serious and devastating of all the diseases affecting citrus. It is estimated that globally HLB has destroyed more than 100 million trees and – a proposal for a regional has spread to several continents including the Americas. Its high socio-economic programme on plant health impact is linked to the fact that all species of citrus are affected and there is no and management of emerging known cure. cross-border diseases The disease is spread by the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, – a panel of experts a tiny insect about 4 mm long, which feeds on the leaves of citrus trees. When the ACP feeds on an infected leaf for about 30 minutes, it can pick up the bacterium, 1 carrying it for many days and transferring It takes 6-8 years for citrus trees to reach in both countries and subsequently, it when feeding on an uninfected tree. peak production levels. The disease requests were made to FAO for technical This bacterium blocks the phloem and tends to target younger trees, making assistance to fill critical gaps. prevents the flow of nutrients, causing it difficult for growers to quickly replace loss of leaves, deformation of fruits plants that have been lost. In many Jamaica which can become bitter and hard, cases, farmers switch to the cultivation early fruit drop and the eventual death of other crops in order to salvage their The citrus industry is of vital of the tree. Grafting infected plant tissue livelihoods, rather than engage in the importance to Jamaica’s economy onto a healthy plant can also spread the costly and time consuming programme in terms of employment, exports and disease. of management required to revive their local production. The total value of orchards. The reduction and loss in citrus the industry is estimated at US$40 Management of the disease is production directly affects employment million, generating employment for compounded by the ubiquitous presence in the field and along the entire value approximately 19 500 persons at of citrus trees across the region, not only chain. Although to date there is no data the industry level (including on-farm on commercial orchards, but also in on social impact, preliminary estimates operations, processing, packaging backyards as a household fruit crop and in the case of Mexico indicate that, in the plant, wholesale and retail trades). Citrus as a particularly favoured ornamental absence of preventative action, direct yields have fluctuated over the last plant, Murraya paniculata or orange employment would be reduced by 14% several years largely due to the effect jasmine (a host for both the ACP and HLB), within 3 years and 39% within 5 years of of Citrus Tristeza Virus (CTV), adverse wherein subtle changes in the health of HLB taking hold. weather conditions, poor management the trees may go unnoticed. Symptoms practices, an ageing farming community may not begin to show until a year or Management of the disease may also and declining acreages. With the more after the tree has been infected, by bring with it a detrimental effect on industry in the midst of the steady which time several or all neighbouring the environment associated with the march to recovery following the mass trees may have become infected. disposal and burning of millions of replanting of trees between 5–15 years trees. Alternately, the intensive use of ago, the encroachment of HLB was a Impact pesticides can cause pollution of soils, source of grave concern. ground water resources and air, and Fruits affected by HLB lose their affect biodiversity. The TCP project, TCP/JAM/3302 commercial value. Along with the – Assistance to manage Citrus direct economic impact of losses in National projects Greening in Jamaica, was approved yield, volume and value of production, in October 2011 and implemented management of the disease is very Jamaica and Belize are two countries of between January 2011 and January costly. Estimates from Brazil, where HLB the Caribbean where the citrus industry 2013 in conjunction with the Ministry of was first discovered in 2004, place costs is socially and economically important Agriculture and Fisheries (MOAF), and at approximately US$403 per hectare, and where HLB was discovered in in close collaboration with the Jamaica too high for small and medium-sized 2009. National programmes for the Citrus Protection Agency (a national producers in the Caribbean to bear. management of HLB were initiated body with the mandate to regulate citrus nurseries in the country), and the Rural Agricultural Development Authority (RADA). The project resulted in: X an assessment of available HLB management options and methods suited to the Jamaican context and the determination of appropriate implementation mechanisms; X development and implementation of an Area-wide Integrated Management Strategy (AIMS), to facilitate a cooperative approach to HLB management by geographically connected farmers; X Training of Trainers (ToT) in HLB management and record keeping. Area-wide management strategies for the psyllid and HLB were implemented and reviewed 2 A total of 97 persons were trained under this component - Free of ACP and/or HLB ACP is present HLB is present 57 Extension Officers of RADA, 27 farmer leaders/key farmers, one nursery operator and one ‣ Launch public awareness ‣ Develop a National ‣ Reduce the vector Plant Quarantine Officer; and surveillance Action Plan for ACP psyllid through the campaigns. management to include: introduction of biological X improved national capability for control to slow the rate diagnosis and detection of HLB, ‣ Train technical staff – surveys / surveillance of spread of HLB. through structural renovation and in the identification activities to detect equipping of laboratory facilities of ACP and HLB. presence / spread ‣ Lengthen the life and and training of eight technicians of ACP (and HLB) productivity of the in disease management. ‣ Limit / eliminate trees through improved Participants were drawn from importation of – introduction of nutrition and weed / the Scientific Research Council citrus plants. biological control grove management. (SRC), MOAF’s Research and - the parasitoid Development Division, the ‣ Develop a Rapid Tamarixia radiata (if Jamaica Citrus Protection Response Plan, in the not already present) Agency (JCPA) and Trade Winds event that ACP (and Ltd (the largest private citrus HLB) are detected. producer and processor); Differentiated management approaches based on disease status X increased capacity to produce disease-free planting material Belize and materials for providing through the establishment of HLB testing service to a screen house for bud-wood The citrus industry is very important farmers and growers; production and an insect-proof to the economy of Belize in terms demonstration nursery; training of employment, livelihood of rural X identification of crop of 20 nursery operators in new communities, exports and local diversification opportunities for nursery management protocols; production. It is estimated that the former citrus growers and a training of 11 technicians and total value of the industry to the Belize review of institutional support officers to introduce new shoot- economy is approximately US$50 required for displaced farmers; tip/micro-grafting techniques million. Employment at the industry for the elimination of graft- level is estimated at 10 000 persons. X recommendations for sustainable transmissible pathogens of citrus; Like Jamaica, Belize went through the funding mechanisms for process of replanting citrus groves to nursery certification and X development of a public