Willow Glen Resident

News

Photograph by Vicki Thompson

Wedgle Injection: Wendell Cox (left) from the San Jose-based company Tru Green injects a tulip tree with insecticide on Aug. 9, as resident Paul Myers watches. Making a small hole in the bark of the tree, the contractors filled the hole with a plug valve. A Wedgle syringe needle was inserted into the valve, allowing the chemical to be injected.

Tulip tree infestation problem is a sticky mess for residents

By Lisa Sibley

Neighborhoods in some areas of San Jose are covered in a sticky, pancake-like syrup. The sidewalks and rocks glisten as the sappy substance shines in the sun. Neighbors can't take their dogs for walks down the sidewalk, and children don't ride their bikes. Strolling through the neighborhood is impeded because the syrup on the sidewalks and beneath the shaded streets is actually bug droppings.

"We call it honeydew," said assistant city arborist Russell Hansen, "but it's basically bug poop."

Some streets in West San Jose, Willow Glen and Almaden, are lined with tulip trees (liriodendron tulipifera). The tall-growing tree native to the southeastern United States, was planted throughout many San Jose communities in the 1950s'-60s, and blooms with an orange flower that resembles a tulip, according to city arborist Ralph Mize. The trees did well until the mid-1990s, when they began developing a build up of sticky sap residue.

That residue is the excrement that comes from the tulip tree scale insect, a tiny brown-black bug, which is infesting the tree, feeding on its twigs and leaves and sucking the nutrients out of the vascular system of the tree.

"They insert a mouth part into the twig itself, into the waterconducting passage of the tree," Mize said. "The insect then forms a shell over itself, making it difficult to spray insecticide on the surface of the tree."

The insects are robbing the tree of the energy and tissues it needs to produce new leaves and roots. As a result, the canopies of these trees are becoming sparse. Leaves drop to the ground, which is already coated with sap.

"It's like you spread pancake syrup all over the neighborhood," Mize said.

The waste product is a mess for homeowners, who are tired of having to wash down their driveways and sidewalks and scrape off the bottom of their shoes. Even their car tires are coated with sap.

"You can't walk on the sidewalk. The only place you can really walk in the neighborhood is down the middle of the street," said Paul Myers, who has lived in West San Jose since 1969. Myers has a tulip tree in front of his house. "You step on a leaf, and the leaf gets into the house and the sap gets on the carpet."

During the mid-1990s, the University of California's integrated pest management program tried to establish a predatory insect to keep the scale in check, Mize said. But the predator never became established, and the scale has been spreading from neighborhood to neighborhood ever since.

Residents have been trying to treat the problem with a systemic insecticide applied as a drench material at the trunk of the tree. Mize explained that the material is taken up through the trunk into the leaves and branches, where the scale comes in contact with it.

"In past years, it appeared to work pretty well," Mize said. " But this year, we suspect because of the spring rains, it wasn't as effective."

To combat the problem, Councilwoman Linda LeZotte's District 1 office provided $5,000 to try out a new experiment. The funding allowed for a test, conducted Aug. 9, where the same chemical that was drenched at the trunk of the tree was instead injected into the tree using a syringe called a Wedgle.

Shawn Espino and Wendell Cox from the San Jose-based company Tru Green were contracted by the city to inject 25 trees in West San Jose on Aug. 9. Making a small hole in the bark of the tree, they filled the hole with a plug valve. A needle was inserted into the valve, allowing the chemical to be injected.

Mize said the best time to apply the insecticide is before the tree "leafs out" in the spring. He was concerned that the efficacy of the experiment could be compromised if the injection was not done at the proper time. The natural life cycle of the insect leads to less feeding and less residue as summer progresses.

Hansen said they'd return in about two weeks to power-wash the sidewalks and see if the sap problem has diminished. They're hoping that the injection treatment, which has not been tried before, will be effective. However, homeowners were skeptical the tree-stem injection experiment would work.

When the problem surfaced the late 1990s in Willow Glen, everything from soil drenching to aerial sprays was tried, Hansen said. But many of the trees had to be replaced with alternatives like sycamores, maple, ash and Chinese pistache trees, which still offer shade but are not affected by the scale insect.

The removal and replacement program at that time was voluntary, and the city paid for it. But today, the burden is back on the homeowners if they want to remove and replace the trees on their property. The city doesn't have an inventory of how many tulip trees still exist.

Mize has received six permits from residents wanting to remove their tulip trees, including one from the Myerses. But before the city approves or denies the permits; he's waiting to see if the injection experiment is successful. Residents said they're looking forward to the city keeping them and their neighborhood association informed of their options.

A series of informal hearings was held to allow all interested parties to express their concerns regarding the tree-removal requests, Hansen said. There are a few West San Jose residents aggressively opposed to the removal of the trees, some of whom don't have tulip trees on their property.

Mize added that prior to the test injections on Aug. 9, one homeowner on Castle Manor Drive was granted a request to remove a tulip tree because the tree's canopy was significantly suffering.

"Continual feeding by insects year after year can result in the death of the tree," Mize said. He added that trees in San Jose are often stressed due to drought conditions, making them more susceptible to insect activity.

Hansen said each tree injection costs about $110-$150 per tree, and the injection process has to be done once a year. After seven to 10 years of injections, Hansen said neighbors could be spending the same amount on injections as it would cost them to remove and replace the tree. A tree removal and replacement can range from $1,000 to $3,000, depending on the tree's size.