Citrus Leprosis and its Status in Florida and Texas: Past and Present

Abstract

According to published reports from 1906 to 1968, leprosis nearly destroyed the Florida citrus industry prior to 1925. This was supported with photographs showing typical leprosis symptoms on citrus leaves, fruit, and twigs. Support for the past occurrence of citrus leprosis in Florida includes: (1) presence of twig lesions in affected orange blocks in addition to lesions on fruits and leaves and corresponding absence of similar lesions on grapefruit; (2) yield reduction and die-back on infected trees; and (3) spread of the disease between 1906 and 1925. Transmission electron microscopy (TEM) examination of tissue samples from leprosis-like injuries to orange and grapefruit leaves from Florida in 1997, and fruits from grapefruit and sweet orange varieties from Texas in 1999 and 2000 did not contain leprosis-like viral particles or viroplasm inclusions. In contrast, leprosis viroplasm inclusions were readily identified by TEM within green non-senescent tissues surrounding leprosis lesions in two of every three orange leaf samples and half of the fruit samples obtained from Piracicaba, Brazil. Symptoms of leprosis were not seen in any of the 24,555 orange trees examined across Florida during 2001 and 2002. The authors conclude that citrus leprosis no longer exists in Florida nor occurs in Texas citrus based on: (1) lack of leprosis symptoms on leaves, fruit, and twigs of sweet orange citrus varieties surveyed in Florida: (2) failure to find virus particles or viroplasm inclusion bodies in suspect samples from both Florida and Texas examined by TEM; (3) absence of documented reports by others on the presence of characteristic leprosis symptoms in Florida; (4) lack of its documented occurrence in dooryard trees or abandoned or minimal pesticide citrus orchard sites in Florida. In view of the serious threat to citrus in the U.S., every effort must be taken to quarantine the importation of both citrus and woody ornamental plants that serve as hosts for Brevipalpus phoenicis (Geijskes), B. californicus (Banks), and B. obovatus Donnadieu (Acari: Tenuipalpidae) from countries where citrus leprosis occurs.

Integrating ecology and genetics to address Acari invasions

“…Efforts to control these species have led to an increase in the number of pesticide applications, crop production costs, and environmental contamination. Estimates of damage caused by eriophyid, tarsonemid, tenuipalpid, and tetranychid mites due to their direct feeding, vectoring of fungi or viruses, and control costs range to millions of dollars (Jeppson et al 1975;Ochoa and von Lindeman 1988;Childers et al 2003;Hong et al 2006). In addition, many poorly known mite species could have a great impact on the diversity of crops and cattle industries that are valued in billions of dollars (Childers et al 2003;Hummel et al 2009;Léger et al 2012).…”

An annotated list of ornamentals naturally found infected by Brevipalpus mite-transmitted viruses

“…Since then, it has been reported from other South American countries (Bolivia, Colombia and Venezuela) as well as from Central American countries (Panama, Costa Rica, Honduras, Guatemala, Mexico) Bastianel et al, 2006). The disease is of concern for citrus growers in the Caribbean region, where the virus is absent, and in the US, where it has not been found since the 1960's (Childers et al, 2003c). The transmission of CL virus by Brevipalpus mites was initially shown in Argentina by Frezzi (1940) and subsequently confirmed in Brazil and US by Musumeci and Rossetti (1963) and Knorr (1968), respectively.…”

Quantitative trait loci analysis of citrus leprosis resistance in an interspecific backcross family of (Citrus reticulata Blanco × C. sinensis L. Osbeck) × C. sinensis L. Osb

“…There are previous reports of leprosis in Florida, USA; however, the disease has not been found in that country for decades (Childers et al 2003a). Currently, leprosis is restricted to several countries in South and Central Americas and has reached the south of Mexico (Bastianel et al 2006a).…”