Ask the gardeners

We have a 4-year-old gloxinia which we've successfully brought through its yearly rest periods. Now, the leaves are starting to curl down instead of laying flat. Is this due to something in the soil? We water the same amount as always, so do not feel this is the cause.

When the leaves curl downward, it's often due to a buildup of fertilizer salts in the soil.

The same thing happens to its cousin, the African violet, and you find it more often when plants are watered from below rather than from the top.

Gently invert the plank and take it out of the pot. Wash by holding the root ball under the faucet, or by swishing the soil ball up and down in a pail of water. Gentle action is the watchword in these operations, which will remove the salts.

You can also let the water run through the pot several times without removing the plant. Be sure to let it drain thoroughly and wait a bit before watering again.

Leaf curl, especially if the leaves in the center become dwarfed and brittle, can also be due to cyclamen mites. Using a magnifying glass, examine for tiny moving specks. If present, flush the tops and bottoms of the leaves with a solution of 1 teaspoon of liquid dishwashing detergent to a quart of room-temperature water.

About 10 years ago I planted an early apple tree (dwarf), and its branches and leaves make a perfect screen between our home and our neighbor's. The problem: The tree produces an abundance of useless fruit. I hate to cut down the tree, but it makes such a mess. Is there some way to keep the foliage green and yet prevent apples from forming?

; You can still let the tree bloom and enjoy its beauty and fragrant blossoms. Then you can get rid of the unwanted fruit by using a chemical thinner. This will get rid of about 90 percent of the fruit.

Try a combination of two chemicals. One is called NAA (Napthaleneacetic acid) used at the rate of 20 parts per million (1 3/5 teaspoons per 100 gallons of water); and the other is Sevin (an insecticide) used at 2 tablespoons per gallon of water.

Both materials are combined in the solution and sprayed from 7 to 21 days after full bloom.

There'll be some wilting of leaves. But this is not serious, and the trees recover fast. Repeat the application in about 10 days. If you have an orchardist friend, he may be glad to give you small amounts of this solution.

Caution: Do not use Sevin when the tree is in bloom, and be sure there are no flowers under your tree where the bees might be working. Sevin is devastating to the bee population.

Note: You may need about 10 gallons of solution, and it would be easier to use the metric system when measuring the proportion of Napthaleneacetic acid. For those who don't like to use chemicals, the alternative is to remove the blooms or young fruit by hand.

If you have a question about your garden, inside or out, send it to the Gardening page, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115. Doc and Katy Abraham are nationally known horticulturists and have been greenhouse operators for 25 years.

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