Citrus strains of Xylella fastidiosa can cause coffee leaf scorch
Artificial inoculation studies carried out in Brazil showed that Xylella fastidiosa (EPPO A1 quarantine pest) strains isolated from citrus plants (causing citrus variegated chlorosis) are pathogenic to coffee plants (causing coffee leaf scorch). Previously, it had been observed that isolates from citrus and coffee were morphologically, serologically and genetically closely related. In Sao Paulo state, Brazil, as citrus and coffee are usually growing in adjacent plots, it is thought that citrus strains originated as selections from a pre-existing population in coffee. Although X. fastidiosa was identified on citrus before coffee, symptoms of coffee leaf scorch had been observed even earlier but were attributed to other causes (in particular to nematodes). In addition, coffee leaf scorch occurs in other Brazilian states where citrus has never been grown and the incidence of coffee leaf scorch is higher than citrus variegated chlorosis. In insect transmission studies, preliminary results showed that Oncometopia facialis and Dilobopterus costalimai can transmit X. fastidiosa strains isolated from diseased citrus plants to coffee plants. Further studies will be made to see whether coffee strains are pathogenic to citrus plants.
Sources
Li, W.B.; Pria, W.D. Jr; Teixeira, D.C.; Miranda, V.S. Ayres, A.J.; Franco, C.F.; Costa, M.G.; He, C.X.; Costa, P.I.; Hartung, J.S. (2001) Coffee leaf scorch caused by a strain of Xylella fastidiosa from citrus.
Plant Disease, 85(5), 501-505.