oleander disease - Knowledgebase Question

Name: Patti Ahern
Santee, Ca
Question by gemcalf3
February 25, 2010
I live in 92071/Santee, CA. I have about 50 white oleanders that are diseased & dying at different stages. What do you suggest to help them/replace them/wait them out? I am just beside myself since we have had the oleanders 35 years & they are privacy screens around our tract home/pool. Do you have replacement suggestions for clay soil & fast growth? Plumbagos,white or blue? Thanks!

Answer from NGA
February 25, 2010


How sad that you are losing your oleanders. I'm afraid there's no good news. Oleander leaf scorch is a disease found mainly in southern California. It is caused by the bacterium Xylella fastidiosa. As with other diseases caused by X. fastidiosa, the bacterium is vectored by insects, primarily sharpshooters, which feed on the water-conducting tissue (xylem) of the plant. There is no known cure for oleander leaf scorch. Pruning out the part of the plant showing symptoms may help the appearance of the oleander tree or shrub but will not save the plant. The bacteria by then have already moved throughout the plant via the xylem, and limbs that show symptoms are only the first to become affected. Research indicates that some cultivars of oleander may express symptoms to lesser degrees than others and may live longer than other varieties when infected. Because of the year-round abundance of the glassy-winged sharpshooter, currently available insecticides are not effective in stopping the spread of the disease. The best management may be early removal of plants infected with the oleander leaf scorch bacteria to reduce the source of inoculum, but there are no experimental data to validate this method. Although only a few plant species have been tested as hosts of the oleander leaf scorch strain of X. fastidiosa, it is possible that other plant species may harbor the bacteria without showing disease symptoms. The bottom line is that you should have your oleanders tested to see if this is in fact what is causing their decline before planting anything in their places. Take samples of the affected leaves and branches to your local cooperative extension office for positive diagnosis. Helpful folks there can then advise you as to what might be safe to plant in their places. The closest extension office is in San Diego but you may be able to mail the samples in to their plant diagnostic center. Contact University of California extension, 5555 Overland Avenue, San Diego - (858) 694-2845. Best wishes with your landscape!

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