I planted an Arbutus unedo about a year ago and it has done great – until recently. The leaves nearest the trunk of the tree and ground are turning yellow and falling off.

I noticed that this condition is slowly moving up the tree and out toward the tip of the branches. I think it's either getting too much water or too little. Do you know what causes this?

– Barry Beal, El Dorado Hills

Arbutus unedo or strawberry tree is a drought- tolerant tree, says UC Master Gardener Mary Griggs. The first question: How frequently are you watering this tree?

It's been in the ground for more than a year, so it should be established by now and not need more than weekly watering. Older established strawberry trees exist in this region on only winter rains. Too much water can yellow the leaves.

It is natural for this evergreen plant to drop the inner leaves, usually when they are about 3 years old. Are younger leaves dropping? Is the plant putting on new growth?

Also, strawberry trees are prone to root and crown rot (Phytophthora spp). This fungus kills the roots and root crown area of infected plants, and sometimes spreads upward into the stem.

Often, a vertical streak, stain or canker becomes visible on infected trunk wood under the bark. Black or reddish sap may ooze from darkened areas of infected bark.

To confirm the presence of this disease, cut away the outer bark around the stain streaks. Reddish-brown streaks or zones can be seen in the inner bark and outer layer of wood if phytophthora is present.

For additional infor- mation on phytophthora and root and crown rot in the garden, send a stamped, self-addressed, business-size envelope to: PN 74133, UC Cooperative Extension, 4145 Branch Center Road, Sacramento, CA 95827.

This pest note is also available online at www.ipm.ucdavis.edu.

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&g@sacbee.com. Please put "Garden Detective" in the subject field and include your postal address.

To contact your UC Extension directly, call:

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

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

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

• El Dorado: (530) 621-5512; 9 a.m.-noon weekdays

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

• Nevada: (530) 273-0919; 9 a.m.-noon Tuesday-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

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