Garden Detective

Garden Detective: What’s wrong with her wisteria?

That ulcer on Beth Goodwin’s wisteria is a sign of crown gall, Garden Detective says.
That ulcer on Beth Goodwin’s wisteria is a sign of crown gall, Garden Detective says.

Q: I have two wisteria vines. The ulcers on one of the vines are what concern me. Do I remove them? The other wisteria doesn’t have ulcers and its foliage and flowers are always better looking.

Beth Goodwin, Sacramento

A: According to UC master gardener June Bleile, the growth on your wisteria is a crown gall. The gall is caused by a bacterium that lives in the soil and enters the plant through injuries. Once inside the plant, the bacterium injects some of its genetic material into the host’s cells, causing it to produce hormones that stimulate small areas of rapid growth.

At first, the galls are tan in color and may be spongy in texture, but eventually harden and turn dark brown or black.

As the disease progresses, the galls can totally encircle the trunk and branches, cutting off the flow of sap that nourishes the plant. This may be why your infected plant is less vigorous than the uninfected plant.

There is no treatment for crown gall. You can remove it if you want a more vigorous plant. However, because the bacterium will remain in the soil for long periods, unless you solarize the soil during the heat of summer, you should not plant another wisteria in the same location.

Q: We have a dead ornamental pear tree in our backyard that’s about 35 feet tall and it is located within 8 to 10 feet from our neighbor’s house. What is the safest and economical way to remove the tree?

Kelly Chen, Davis

A: According to UC master gardener Annie Kempees, it’s time to call in some experts. To remove a large tree, contact tree service companies. Check to see the company is fully insured and licensed. It is recommended to get more than one bid for services.

For some suggestions in your area, contact the Yolo County master gardeners office at (530) 666-8737.

Garden questions?

Questions are answered by master gardeners at the UC Cooperative Extension services in Sacramento and Placer counties. Send questions to Garden Detective, P.O. Box 15779, Sacramento, CA 95852. Send email to h& Please put “Garden Detective” in the subject field and include your postal address. To contact UC Extension directly, call:

Sacramento: (916) 875-6913; 9 a.m.-noon and 1-4 p.m. Monday-Thursday

Amador: (209) 223-6838; 10 a.m.-noon Monday through Thursday; email ceamador.

Butte: (530) 538-7201; 8 a.m.-noon and 1-5 p.m. weekdays

Colusa: (530) 458-0570; 9 a.m.-noon and 1-4 p.m. Tuesdays; website:

El Dorado: (530) 621-5512; 9 a.m.-noon Tuesday-Friday

Placer: (530) 889-7388; 9 a.m.-noon on Tuesdays, Wednesday and Thursdays or leave a message and calls will be returned; website:

Nevada: (530) 273-0919; 9 a.m.-noon Tuesdays through Thursday or leave a message

Shasta, Tehama, Trinity: (530) 225-4605

Solano: (707) 784-1322; leave a message and calls will be returned

Sutter, Yuba: (530) 822-7515; 9 a.m.-noon Mondays and Tuesdays and 1-4 p.m. Thursdays

Yolo: (530) 666-8737; 9-11 a.m. Tuesdays and Fridays, or leave a message and calls will be returned