Plant pests: Oleander leaf scorch and emerald ash borer

Updated Mar 31, 2017
Photo: WikipediaPhoto: Wikipedia

Green Solutions Landscaping’s motto is “listen to your yard” and the Scottsdale, Arizona-based company has been hearing alarm bells from clients’ oleander plants lately.

What is commonly mistaken for drought symptoms, oleander leaf scorch (OLS) is actually the culprit for oleanders yellowing, drooping and appearing scorched by the sun.

The evergreen flowering shrub is popular in desert areas even though it isn’t native due to its hardiness to drought, wind, heat, pollution and salt exposure.

OLS was originally discovered in Southern California in the 1990s and since then it spread to Phoenix, Arizona, in 2004. The disease is caused by the bacterium Xylella fastidiosa and is spread by insects, primarily sharpshooters.

The sharpshooters feed on an infected plant and then the bacteria multiplies in the insect’s mouth so it becomes infectious for life. As the sharpshooter moves on to feed on other plants, the bacteria are transferred into the next host plant and spreads throughout the xylem, reproducing until the plant can no longer conduct water within itself.

There is currently no cure for OLS and while pruning off the noticeable infected portions can help with appearances, it will not help the plant survive as the bacteria will have already spread throughout the entire xylem system.

“We can’t even give our clients a timeline as to when they’ll lose their plants,” Julian Meier, owner of Green Solutions Landscaping, told PR Underground. “Some will survive for a year of two. But, in our experience, most oleanders will die within three to five years after their initial infection.”

Meier advises lab testing to rule out any other factors that may be causing the yellowing and dieback.

If there are other oleanders in the landscape that are still healthy it is best to remove and destroy the infected oleander immediately.

Extension works with Bartlett Tree Experts to battle EAB

In an effort to help control the rampant emerald ash borers (EAB), the Virginia Cooperative Extension has partnered with Bartlett Tree Experts in Roanoke to provide a series of workshops.

EAB appeared in Virginia in 2003 and it is theorized that the insect spread via nursery stock and firewood from out of state.

“The emerald ash borer has gotten loose in the wild and is attacking all the ash trees in Virginia, which make up about three percent of our forest inventory, mostly around creeks and streams,” Jason Fisher, a Virginia Cooperative Extension Agent, told “Ash is an excellent tree for fire wood and lumber and we stand to lose all of our ash trees to this pest.”

The state is currently under a federal quarantine that prevents the interstate movement of firewood and nursery stock. The pests eat ash tree leaves and then the female lays its eggs in the tree bark. The larvae bore into the tree and destroy the tree’s ability to feed itself.

The Emerald Ash Borer and other Tree Pests – A Woodlot Series is sponsored by Bartlett Tree Experts, the Virginia Department of Forestry and Virginia Cooperative Extension and will be held on April 6 from 10 a.m. to 3 p.m. at the Claytor Nature Center in Bedford.

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