First report of citrus blight disease in Mexico
Citrus blight disease (EPPO A1 quarantine pest) is a serious tree decline of unknown etiology, reported in Florida and Louisiana (US) and several countries in South America, southern Africa and the Caribbean. As there are no reliable symptoms, physical and chemical tests have to be used for diagnosis (water injection into the trunk, zinc and potassium analysis of the outer trunk wood, immunological test for specific blight protein in the leaves). Tests were done on declining citrus trees in Yucatan, Mexico, in June 1996. Results showed that these trees are affected by citrus blight disease. This is the first report of this disease in Mexico. The authors felt that the lack of earlier reports was probably due to climatic conditions and also to changes in rootstocks. Because of the threat of tristeza, growers are planting Valencia orange grafted onto Cleopatra mandarin (C. reshni) and onto Volkamer lemon (C. volkameriana) which are both susceptible to citrus blight (but less to tristeza) instead of the usual sour orange rootstock (C. aurantium) which is highly resistant to citrus blight.
Sources
Wutscher, H.K.; Cervantes, A.; Derrick, K.S. (1997) Citrus blight found in Yucatan, Mexico.
Plant Disease, 81(5), p 551.