Also serving the communities of De Luz, Rainbow, Camp Pendleton, Pala and Pauma

Roger's pick- Oleander Leaf Scorch

Oleander plants have been a real durable plant over the years; they have been drought tolerant and, until recently, fairly bullet-proof in our gardens.

However, the oleanders now have some major problems to contend with that are taking down tens of thousands of these plants throughout Southern California.

This problem is a fairly new disease called Xylella fastidiosa, and is the same species, although a different strain, that causes Pierce’s disease that occurs in grapevines and almonds.

As with other diseases caused by X. fastidiosa, the bacterium is carried by insects, primarily glassy wing sharpshooters, which feed on the water-conducting tissue vessels.

This disease first appeared on oleanders in the Palm Springs-Indio area and in Tustin. (Orange County in the early 1990’s and the disease has spread to other parts of Southern California including Santa Barbara, Ventura, San Diego, San Bernardino, and Los Angles counties very rapidly.)

Once this pathological disease infects the oleander plants, they can die within three to five years after infection, according to experts at U.C. Davis.

Some symptoms are found year-round, although more noticeable in late spring and summer when the infection can develop more quickly in warmer months. Leaves on some branches may turn yellow and begin to droop; then the leaves’ edges turn a darker yellow or brown and eventually dehydrate and die. As this leaf disease progresses, more branches of the Oleander become infected and the plant slowly dies.

The glassy winged sharpshooter is the culprit. It has transparent wings and is brown on top and is slightly lighter in color beneath. There are two generations per year of these sharpshooters in California and they can build up populations fairly quickly and cause major havoc.

It is important to note that when pruning or cutting out the infected plants not to transmit this disease on your pruning tools or saws. There is no current cure for this disease and the best suggestion from the University of California’s Department of Agriculture is to remove the infected plants from the landscape setting.

With the vast numbers of oleanders that have been planted over the decades it is important to understand the severity of this disease. For if these dead and dying plants are to remain around your garden, they pose a fire hazard. The dead plants act as fuel, which is another reason to consider the elimination of these hazards.

Roger Boddaert is a landscape designer and horticultural consultant at (760)728-4297.

 

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