Citrus Blight and Other Diseases of Recalcitrant Etiology.

摘要: Several economically important diseases of unknown or recently determined cause are reviewed. Citrus blight (CB), first described over 100 years ago, was shown in 1984 to be transmitted by root-graft inoculations; the remains and is controversial. Based on graft transmission, it considered an infectious agent some; others suggest that CB abiotic. variegated chlorosis, although probably long present Argentina, where a variant CB, identified as specific disease caused strain Xylella fastidiosa after if reached epidemic levels Brazil 1987. psorosis, 1933 virus citrus, perhaps one last characterized. In 1988, very unusual virus. The lettuce big vein appears viruslike soilborne fungus. Double-stranded RNAs were associated with disease, suggesting may unidentified RNA Rio Grande gummosis, dry rot root, peach tree short life, some replant complex etiology. Various microorganisms have been isolated from trees these diseases, but attributable part environmental factors. Determination etiology has proven difficult, part, because they affect only mature trees.