During the summer, our pine and redwood trees turned brown next to the tree trunk. Did we water too little or too much? Or is this a sign of disease?

The trees have been in the ground more than three years and are about 20 feet tall. We have horrible, rocky clay soil. We water three times a week for 20 minutes three times a day on drip.

– Nancy Baker, Rancho Murieta

The cultural requirements of pines and redwoods are different, so a positive identification of the trees would be beneficial, according to UC Master Gardener Liz Haines. However, both redwoods and pines routinely shed old foliage, which may be the browning to which you refer.

Irrigating three times a week in heavy soil may be excessive, particularly for the pine. To determine irrigation frequency, additional information is needed on the watering methods, how many emitters and the number of gallons per hour emitted.

For identification, to determine the trees' health status and to discuss their cultural needs, bring samples from your trees to the Sacramento County Cooperative Extension office, 4145 Branch Center Road, Sacramento. The office is open 9 a.m. to noon and 1 to 4 p.m. weekdays.

We planted an apricot tree three years ago and we just pruned it to a height of 9 feet. Do we leave the little twigs on the branches that have leaves on them or are we supposed to strip the branches of all the mini twiglike branches that have the leaves?

– Jon Brandes, Folsom

When pruning your apricot tree, leave the small twigs on the tree, says UC master gardener Annie Kempees. Some of those twigs are the spurs that will produce the fruit. If they are closely spaced, thin them.

Unlike most deciduous fruit trees, apricot trees aren't pruned in winter. Because apricots are susceptible to infection by the branch-killing disease Eutypa dieback, it is best to prune apricot trees in the summer – usually July or August – so that the tree has at least six weeks of rain-free weather after pruning.

Eutypa dieback – also known as Cytosporina, gummosis, and limb dieback – causes limbs or twigs to wilt and die suddenly in late spring or summer with the leaves still attached. The bark has a dark discoloration with amber-colored gumming. Infected areas in the interior of the wood are discolored brown.

For more information on Eutypa, visit the UC integrated pest management website 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 through 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 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

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