Question: Are there any new developments regarding oleander leaf scorch?
Answer: This devastating disease is being spread throughout Southern California by a type of leafhopper known as the glassy-winged sharpshooter, which punctures the oleander's soft, new growth as it feeds, injecting bacterium.
Symptoms of baterial scorch include leaf-tip dieback and scorched yellow, light brown or rust-colored leaf margins, which usually start with one plant section. As the disease progresses, more sections of the plant die.
There is no known cure. An infected plant will probably die within two years.
To control the spread of this disease, the home gardener has several options.
Aggressive pruning appears to substantially delay (but not halt) the disease. Prune at least 1 foot below infected areas. Clean pruning tools between plants with a solution of 1 part bleach to 10 parts water.
If one among several oleanders appears infected, remove the infected plant quickly; it is a source of bacteria that can be spread to other oleanders by the sharpshooter.
Researchers may study a cultivar believed to have some tolerance to the disease, but for now they recommend replacing oleanders with other species.
Have a problem in your yard? University of California Cooperative Extension (UCCE) Master Gardeners are here to help. These trained and certified horticultural volunteers are dedicated to extending research-based, scientifically accurate information to the public about home horticulture and pest management. They are involved with a variety of outreach programs, including the UCCE Master Garden hotline, which provides answers to specific questions. You can reach the hotline at (714) 708-1646
or send e-mail to firstname.lastname@example.org. Calls and e-mail are picked up daily and are generally returned within two to three days.
A UCCE Master Garden training course begins in January. Applications are being accepted. Call or e-mail the hotline for more information.