Mundulla Yellows (MY) is a newly recognized lethal dieback of unknown etiology affecting Eucalyptus spp. in Australia (1). Progression of symptoms, unlike other disorders described for eucalypts, starts as foliar interveinal chlorosis on one branch followed by branch dieback advancing toward the main trunk. Epicormic shoots with symptomatic leaves typically develop proximal to the dying zone. Continuing dieback leads to tree death in 5 to 20 years. MY trees occur singly or in small foci and do not recover even if affected branches are removed. MY-like symptoms developed on seedlings grafted with bark patches from MY trees (1). There is no evidence for a fungal, phytoplasma, or other bacterial etiology. In a search for a putative virus-like agent we have identified an electrophoretic pattern (2) of several single-stranded RNAs with apparent size of 200 to 600 nt that is consistently associated with MY and absent from disease-free trees (unpublished). The RNAs are not yet characterized, but the pattern can be used as a preliminary confirmatory “fingerprint” for MY. We report here that MY-like symptoms occur in southern Spain and the Spanish island of Ibiza. RNA fingerprints closely resembling those of MY, were detected in symptomatic trees (4 of 4 of E. camaldulensis and 1 of 1 of E. globulus) from Valencia, Spain. MY therefore, appears not to be limited to Australia.
References: (1) D. Hanold et al. Landscope 17(4):41, 2002. (2) J. W. Randles. Strategies for implicating virus-like pathogens as the cause of diseases of unknown etiology. Pages 315--332 in: Diagnosis of Plant Virus Diseases, CRC Press, Boca Raton, FL, 1993.
