The citrus industry is of significant economic importance to the US, so when any potential pest appears on the horizon there is cause for concern. When the lime swallowtail (Papilio demoleus) was found in the Caribbean in 2006, scientists realised that it may only be a matter of time before these strong fliers appear in America. To try and keep one flight ahead of this zesty pest, scientists have come up with a rather neat solution.
Mexico is the latest to succumb to the inevitable spread and establishment of huanglongbing (HLB) – the devastating disease of citrus crops. Mexican authorities in the states of Jalisco, Michoacán and Colima have warned growers that HLB – otherwise known as citrus greening – is here to stay.
HLB was first detected in Mexico in July 2009 and it’s clear now that it won’t be going away. Some estimates suggest HLB could affect 60% of Mexico’s citrus industry, an industry which provides employment for 70,000 farmers. SENASICA, the National Service for Animal and Plant Health, Food Safety and Quality, has invested over US$20 million to control the disease. An economic impact assessment report prepared this year by consultants specializing in the economics and finance of plant health programmes indicated total losses to the Mexican economy could amount to almost $7000 million.
Mexico’s not the first to report the alarming consequences of HLB infection. The disease has been known in Brazil for some years and is spreading throughout the region. Florida first reported the disease over 5 years ago and data from 2010 showed 18% of trees in Florida are infected – for more information on the disease in Florida click here. HLB was first reported in Nicaragua and Honduras in 2010 and in Costa Rica in February this year. A recent outbreak in the Dominican Republic is said to have destroyed 34,000 trees and left 5000 unemployed.
The detection of the Asian citrus psyllid (Diaphorina citri) in a citrus grove in Ventura County, California, has set alarm bells ringing in the Californian citrus industry, and led to the imposition of a quarantine in the County just as the citrus harvest was getting under way. The psyllid, now found throughout Florida and present in a number of other U.S. states, is a serious pest of citrus, and is the primary vector for citrus greening (also called Huanglongbing or HLB), one of the more serious diseases of these fruit crops. All citrus and closely related species are susceptible hosts for both the insect and the disease, and there is no cure once a tree is infected with HLB.