ANSWER: The most likely problem is Nerium canker, caused by a bacterium, Pseudomonas syringae pathovar savastanoi. Galls and lesions may damage stems, flower parts, seed pods, peduncles, and young leaves. Mature galls on stems are 1-2 cm in diameter. Galls on succulent twigs may appear cankerous because the tissues first infected die, and the stem may split at that point. Leaves, flowers, and seed pods develop wart-like galls and become distorted. The seed pods may be twisted and stunted. Only fresh wounds are suitable infection courts. Wounds include leaf scars (susceptible for a few days), damage from pets, children and workers, high wind, and pruning cuts. In areas with distinct wet and dry seasons, nearly all infection occurs during the wet season - approximately October to May in California. Control efforts may be only moderately effective. Do not allow a sprinkler irrigation system to wet the leaves (mulch and use drip irrigation if necessary). On some fruit trees, there is evidence that a bed of mulch releases yeast spores that compete with plant pathogens on plant surfaces. By all means, do not work with plants when leaves are wet because you can carry epiphytic (surface growing, not yet infecting the leaves or plant parts) bacteria to other plants and introduce them into unnoticeable leaf wounds. Minimize worker, children, and pet activity in the vicinity to minimize wounding. Minimize or avoid nitrogen fertilizer in the vicinity because an excess of Nitrogen leads to tender succulent growth that is probably more susceptible to this bacterium.

Another possibility is an anthracnose disease canker, caused by a fungus, Gloeosporium. It may be seen on branch tips, especially after freeze injury, environmental stress, improper nutrition, or natural senescence; or along branches. Control suggestions include sanitation pruning to remove dead and diseased twigs, avoiding overhead irrigation (sprinkler system) because leaf wetness allows the fungus to infect new wood and to splash spores from diseased wood to healthy wood.

MARK BLACK, EXTENSION PLANT PATHOLOGIST adds:

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I would add one more disease for South Texas. The question I answered earlier was directed primarily at the Napa, CA area and also based on their description of stem cankers. The Texas' question is probably for a different symptom: leaf scorch and severe limb dieback, and even plant death.

Larry Barnes, Plant Pathologist in College Station (and workers in California also) have positive serology tests from oleander with scorch and dieback for Xylella fastidiosa, a xylem limited bacterium vectored by plant hoppers. If this sounds familiar, this is the same name used for the Pierces Disease pathogen in grapes. The bacteriologist tell me that the grape "strain" is different from the numerous strains that get in a lot of woody plants, and that
X. fastidiosa in trees does not infect grape. I would consider this disease in oleander non-treatable. There have been experimental injections with antibiotic that improved symptoms (I think the host plant was a shade tree), but symptoms developed again after a period of time. This was one piece of evidence that the disease was caused by a bacterium. There is no label for this use of antibiotics, and it would be impractical on multiple trunk species like oleander, and probably even impractical on single trunk trees. I have seen symptoms that fit this on oleander in Kinney and Uvalde Counties I recommend replacing affected oleanders with a native such as TX. Mountain laurel, evergreen sumac, or cenizo.

HERE IS AN ARTICLE WRITTEN ABOUT THE PROBLEM IN CALIFORNIA:

PlantHealth
California's oleanders devastated by disease
Text by DON DALE

In what could signal a huge economic loss, the advent of oleander scorch in the Los Angeles area may cost growers their entire oleander inventory. The disease, also called oleander leaf scorch, showed up in the Palm Springs, CA, area in approximately 1990 and has since spread to Los Angeles and Orange counties. It is caused by Xylella fastidiosa--the same bacteria implicated in Pierce's disease, which has long plagued the wine industry and is vectored by the glassy-winged sharpshooter (Homalodisca coagulata). The insect pest is native to the South and serves as a vector when it feeds on the xylem sap from one plant and transfers it to another.

There is currently a quarantine on nursery stock leaving Los Angeles County in order to ensure no glassy-winged sharpshooters are being shipped to other parts of the state. Species are inspected at both the shipping nursery and the destination, and even one sharpshooter egg mass can cause plant rejection.

According to Dr. Jerrold Turney, the Los Angeles County plant pathologist, these inspections have become a tremendous problem for nurseries because although oleander scorch may not currently affect a wide variety of plant species, there are some 200 hosts listed for glassy-winged sharpshooter. 'It's a very expensive program for the nurseries," the expert added, and there are high costs associated with chemically treating nursery stock against this insect pest.

The sharpshooter is active year-round in much of warm Southern California, and in that part of the state masses of oleanders are dying from this bacterial disease. "There's no treatment. It's fatal," explained Turney. According to the plant pathologist, leaves of infected plants turn grayish green and wilt; they do not respond to watering, as is the case with some instances of wilting. Then, in a period of one to two months, foliage begins to turn brown. "Then another branch will become symptomatic," Turney added.

Oleander scorch gets progressively worse, eventually killing the plant. It may take some time for the entire plant
to become infected, and death typically occurs between one and three years after initial infection. 'This bacteria is native and occurs throughout the United States," Turney noted, though the professional hasn't heard of any oleander die-off in other parts of the country.

Oddly enough, the same species of bacteria also affects grapes; however, if the bacterial isolates from grapes are
placed on oleanders, they will not infect the plants with scorch. The reverse is also true. And although the disease can be controlled in the wine industry by encouraging growers to select resistant rootstock, there is no similar option available to nursery professionals who grow oleanders or other susceptible species. X. fastidiosa samples taken from different plant species are called "pathovars," because they can't be distinguished from each other by species (bacteria identification is problematical) but can be identified by the plants they infect.

The financial loss sustained by nursery professionals could be enormous, Turney said. Already, oleanders are dying along some California freeways, where the plants are staples of the landscape. The expert estimated the California Department of Transportation has planted 25 million oleanders in the southern part of the state, and their loss would require a significant outlay for removal and replacement. 'I think in the next 10 years we'll lose the vast majority of our oleanders," Turney predicted. A very real fear, he said, is that X. fastidiosa will ultimately infect other plants. In that case, other species could go the way of the oleander.

According to Turney, the bacteria also causes almond scorch, alfalfa dwarf and peach stunt, among other diseases. It currently is showing up on - and killing - olive, sweet gum and purple-leaved plum trees in California's Riverside County.

For more information, visit the University of California's Cooperative Extension's Web site at: www.ipm.ucdavis.edulindex.html