IN THE GARDEN PEACHES CAN THRIVE DESPITE SETBACKS.

Byline: JOSHUA SISKIN

Q: I have a peach tree that is 10 years old and produces healthy foliage but not an abundance of fruit. This season, the squirrels also had a field day and I managed to salvage only three peaches despite having placed three foil owls - which were supposed to discourage the squirrels - in the tree. Occasionally, I give the tree a shot of Epsom salts. Is there something else I can do to produce more fruit?

- Edith Silvagni

A: As far as increasing fruit production is concerned, you should know that peach trees are heavy feeders and benefit from at least two fertilizations per year. Epsom salts - which contain magnesium sulfate - are a helpful supplement in any Valley fertilization program. Magnesium is a micro-nutrient needed for photosynthesis and sulfate will acidify the soil, which is a definite side benefit since our soil pH tends to be overly alkaline. Most plants prefer a soil pH of around 6.5, while Valley soil pH is 7.5 or higher.

The best time to fertilize a peach tree is rapidly approaching since, as it turns out, summer's end to midautumn is the time when peach trees make most of their root growth. You should also fertilize in late January to take advantage of the heavy rains that typically come down in February.

It is also necessary to thin the fruit on your tree when it is one inch in diameter. At this size, make sure that fruits on the same stem/branch are separated by at least eight inches. If fruit is not thinned, it will be so plentiful that individual fruits may not have the strength to stay on the branch through ripening and will be very small in size if they do finally mature.

No matter how much fruit you get, it will all be for naught if you cannot keep squirrels out of your tree. The only way to do this is to keep all branches six feet away from structures and utility wires since that is the distance a squirrel is capable of jumping. To keep squirrels from jumping from the ground up into the tree after fruit appears, you can either put a tall portable fence up around the tree or remove all lower branches and wrap a two foot wide band of sheet metal around the trunk at a height of six feet. Having said all this, you want to make sure you have a peach variety that is suitable to your area and that it gets direct exposure to most of the day's sun.

Q: Around three years ago I purchased and transplanted eight Jackson & Perkins tree roses of varying colors. All of them have done extremely well but I keep hoping that the suckers will go away if I keep snipping them. No luck! Please advise what I could do to kill or at least thwart the suckers.

- Dorothy Koetz

A: Stand opposite the sucker, grasp it tightly with one or both hands, and snap it off with a quick downward motion. It is extremely important to remove suckers before they become woody. Once a sucker has hardened off, it cannot be snapped off but will have to be cut. In this case, dig the soil out to the point where the sucker is attached to the plant and cut it off as close to the stem/trunk as possible.

ALLERGIES AND TREES: A number of weeks ago I recommended planting a Londonplane tree (Platanus acerifolia) because of its attractive cream- to gray-colored trunk, vertical growth habit and maple leaf foliage.

Lou, a reader from Glendale, e-mailed to say that this tree, being a close relative of the sycamore, is ``one of the most allergenic (9 on a scale of 10) trees.'' It shares this distinction with other commonly planted trees, including elm, oak and liquidambar.

Because of his wife's arboreal allergies, they cannot live within 300 feet of any of these types of trees. Lou makes an interesting point: ``If you plant a tree that is consistent with other allergenic trees in the immediate area, one more sycamore/oak probably won't hurt. However, if the planted tree is different from those which exist in the immediate area, it may affect neighbors, or even members of your own family, in the form of allergic reactions.''

TIP OF THE WEEK: Speaking of liquidambar, a relatively new variety called `Rotundiloba' is available that does not produce the annoying spiked seed capsules of the regular species. In the fall, its foliage still changes to the pink, red, purple and burgundy colors for which classic liquidambars are famous.