Garden Detective

What made those weird holes?

Q: I’m sending you a picture of what we found on our orange tree. We would like to know if you know what it is and what we can do to treat it. And is the tree going to die from this?

Diane Herlihy, Sacramento

According to UC master gardener Annie Kempees, a definitive diagnosis could not be made from your photo.

Some more details are needed. Do you see injury to the bark? If yes, are the wounds on the surface of the bark, or do they penetrate through the bark? Does any fluid or sap flow from the wounds?

Overall, how is the tree’s health? Does the tree have yellow leaves and dead branches?

This information, combined with clearer photos, will aid in diagnosis of the issue. Call your master gardener office and arrange to bring in more photos or samples.

Most likely, the holes were “drilled” by a woodpecker or sapsucker. These birds tend to come back to the same spots again and again. Usually, the tree’s trunk will heal itself without assistance. But if the damage is too extensive, it can weaken the tree. The tree may lose sap and its overall health start to decline. The holes also invite invasions by pests.

The only way to stop woodpeckers and sapsuckers from drilling a favorite tree is to deny them access. If a homeowner sees holes and is concerned about the potential for further damage, the tree can be wrapped with wire mesh covering a large area of the trunk and major branches. Netting the entire plant is effective for small trees.

Applying sticky or tacky bird repellents can sometimes be an effective deterrent.

Q: I have some boxwood bushes that slowly are turning yellow and die. Can I salvage any, or do I have to replant them after some years? I would appreciate any information you can give me.

Tanina Scimem, Carmichael

A: According to UC master gardener Annie Kempees, there are a number of possibilities for the decline of your boxwood plants. For example, root and crown rots can be a problem when there is excess soil moisture and poor drainage. The diagnosis will determine if any of your shrubs can be saved and what to do before planting more.

Boxwood is sensitive to alkaline soil and needs adequate water. After watering, the soil should be damp to at least a depth of 12 inches. Adjust your watering to achieve this goal. When watering, make sure that the water is not pooling at the base of your shrubs. Also, verify drainage is adequate in the root zone area.

There is also a possibility that the plants are infested with spider mite insects. Symptoms include foliage that is bleached, discolored, stippled or streaked. Plants may also have a fine webbing. The boxwood leafminer would result in sparse foliage, leaves with blisters, or yellow spots, with shoots dying back.

If possible, bring a sample of the affected part of your plants to the Sacramento UC Cooperative office, which is located at 4145 Branch Center Road, Sacramento, CA 95827. Please call the office at (916) 875-6913 for hours.


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;

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Nevada: (530) 273-0919;

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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

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