‘Petite Salmon’ oleander has demonstrated some resistance to oleander leaf scorch
Q. I have oleanders that are dead or dying. I am told this is due to the sharpshooter insect and that there is nothing that can be done to get rid of this pest. The plants are about 6-feet-high and about 25-feet-long and are about 30 years old, screening the street from the back and side yards. I live in Granada Hills and have the sun in the morning in the back yard. The row of oleanders face north and get a lot of wind during the windy season.
The soil is sandstone. The red flowering ones appear to still be thriving while the white ones have died. Can you recommend a replacement for the oleanders that take full sun, make a good screen and grow as fast as the oleanders? ”
– Fred Lipman
Granada Hills
A. The half-inch long glassy-winged sharpshooter, an insect with tent-like, transparent and brownish wings with red veins, moves with fits and starts around oleander stems before hopping from one branch or plant to the next. When it sucks sap from an infected plant, it imbibes a pathogenic bacteria along with the sap.
With its sucking and piercing mouthparts, the sharpshooter also injects saliva into the plants it visits, so that once it ingests the bacteria, it brings it to successive plants in a given area. The bacteria enters the oleander’s water-conducting xylem vessels and clogs them with gel, preventing water from moving up into the leaves. Thus, oleander leaf scorch is the result of desiccation from lack of water moving through the plant. The offending bacteria was first discovered in 1892 in Anaheim, where it was found in defoliated grapevines. It can affect citrus trees as well. There are highly toxic pesticides that may offer some control of the sharpshooter, but home gardeners are not inclined to use them. Parasitic wasps have been introduced that have had some measure of success in depressing sharpshooter populations. ‘Petite Salmon’ and ‘Petite Pink’ semi-dwarf oleander cultivars have
demonstrated some resistance to leander leaf scorch.
When it comes to plants for oleander replacement, you can choose from several Califronia native species. Flannel bush (Fremontodendron californicum), with stunning yellow-orange, cupped flowers in spring and early summer has a natural V-shaped form and grows to 20 feet or taller. Through judicious pruning while it is still young, you may turn it into a hedge.
You do not want to cut into old wood, however, since this can lead to the plant’s early decline and death. Flannel bush is especially fond of sandy soil such as your own and quickly dies when planted in clay or poorly drained soil. Flannel bush leaves and stems are covered with fuzz and so you need to don long sleeves, gloves, and a dust mask prior to pruning. Two varieties, ‘California Glory’ and ‘Pacific Sunset’, hybridized at the Rancho Santa Ana Botanical Gardens in Claremont, are recommended.
Other water thrifty natives that may be grown as hedges include laurel sumac (Rhus or Malosma laurina), a sprawling shrub growing 15 feet high and wide; lemonade berry (Rhus integrifolia), reaching 8-feet tall with attractive pink flower clusters and flavorful fruit; sugar bush (Rhus ovata), growing up to 10 feet with handsome, leathery foliage; toyon (Heteromeles arbutifolia), an 8-foot tall shrub that grows in all types of soil, showing white flowers, red berries, and serrated leaves; California bay laurel (Umbellularia californica), requiring partial shade in our area but probably the native most amenable to shaping into a formal hedge, whose foliage has the same camphor fragrance associated with its more common bay leaf cousin (Laurus nobilis) which, incidentally, may also be grown into a hedge when it is protected from afternoon sun. Note: all of the Rhus species mentioned above contain dermatitic sap.
Italian buckthorn (Rhamnus alaternus) is a Mediterranean, hedge-worthy shrub with glossy dark green foliage that grows 20-feet tall and thrives with little water. Its ‘Variegata’ cultivar has leaves with cream and lime green coloration.
Italian buckthron grows in sun or light shade and survives freezes down to 15 degrees F. Lastly, the common Australian bottlebrush (Callistemon citrinus), which displays brilliant scarlet inflorescences on and off throughout the year, is easily trained into a dazzling hedge for sunny exposures.
Q. Our gopher problem is overwhelming. We have bobcats, deer, raccoons and red tail hawks, so we won’t use poison. Coyotes used to be more visible in our neighborhood and they would eat the gophers but since the coyotes have just about disappeared, the gophers have taken over. Do you have a remedy that actually works to get rid of gophers?
– Boris and Olga Pinevich, Hollywood Hills
(near Runyon Canyon)
A. If you have a fenced yard, there is evidence that a frisky dog that likes to hunt will discourage gopher activity by digging up their tunnels. In the wake of your dog’s excavations, you may have to fill in a few craters here and there, but at least the gophers will be gone. A spry cat or two may also chase gophers away. You can encourage rodent consuming barn owls to take up residence in your neighborhood by constructing a nesting box for them. For building instructions, go to http://www.rain.org/~sals/barnowl.htm. Maccabee gopher traps, available at most hardware and home improvement centers, are also an option.
Tip of the Week
I just received a catalog from Baker Creek Heirloom Seeds that I highly recommend for connoiseurs of exotic vegetables. Flipping through the catalog, I saw a list of more than 20 varieties of purple tomatoes, 30 varieties of hot (chili) peppers, and more than 50 different melons, including dark green serpent melons from Armenia that look like cucumbers and grow three-feet long. You can order a free catalog at www.rareseeds.com or by calling 417-924-8917.
