Q: Some of my house plants have one or two yellow leaves on them. What causes this?

A: Yellow leaves ae often caused by overwatering or poor drainage. Foliage house plants don't need to be watered as often during the short days of November, December, January and February. With only nine or 10 hours of daylight, the plants do not use as much water and unless watering is reduced, root-rot may develop.

Q: My small avacado plant's leaves turn brown and crispy, but it continues to get new ones. Do you know what is wrong?

A: It could be due to spider mites (insects), tiny creatures hard to detect without a magnifying glass. If it's infested, put it under the shower to wash them off.

Q: Has anybody tried the anti-transpirants to protect evergreen plants outdoors during the winter?

A: At colonial Williamsburg they've had some success with Vapor-Gard and Wilt-Pruf. They reduce the loss of moisture from leaves and needles during severly cold weather -- when the ground is frozen to a depth where the roots cannot get water to replace that lost by transpiration. Usually one application is adequate for the winter.

Q: Is an oak tree good to plant in our front yard?

A: Almost all oaks make excellent shade trees. They may grow slower than maples but in the long run are less troublesome and live much longer. The most popular is the willow oak, relatively insect-free and disease-free. All oaks do best in deep, well-drained soils. Thir roots are spreading and often deep. The red oaks usually live a hundred years or more, the white oaks even longer.

Q:I have an old apple tree with many dead limbs. I hate to cut it down because it shades one side of the house in the winter. Can I rejuvenate it?

A: Remove all dead wood. Cut out side branches that are rubbing, crossing and interfering with good branches. Once pruned like this, the tree will send out many new branches. Remove these when they get a foot long, if they aren't in a desired place. It will take about three years to get the tree back to normal shape. Most times it's better to remove it completely and plant a new one.

Q: Is there any remedy for a pear tree with fire blight?

A: If the blight is on the end of a branch, cut that branch back eight to 12 inches beyond the infestion, to a side branch if possible. Cut out diseased wood as soon as it's discovered. If a young tree has dead wood to the trunk, chances are it won't live very long.

Q: For the first time I have seen a flower arrangement with poinsetta stems in it. It looked stunning. Do they need some special treatment?

A: Cut poinsettias can be used in all sorts of floral design work. Normally they will last about 14 days at room temperature after being cut if the leaves are removed (the green leaves, not the colored bracts.) If the leaves are necessary for the design, place the cut stem in warm water (70 to 90 degrees) or singe it over a flame. Stems placed in boiling water for 30 seconds will hold about five days with the leaves attached. Cut poinsettias can be used successfully in foam materials as well as in plain water.