GARDENING CLINIC IN ROCKVILLE

Tuesday at 7:30 the Rockville Department of Recreation and Parks, in cooperation with the Montgomery County Extension Service, will hold a gardening clinic in the Civic Center Mansion, Edmonston Drive and Baltimore Road. The program's free, but registration is required. Call 424-3184,

A ROSE GROWS IN AFRICA

The Potomac Rose Society will meet Wednesday at 8 in the Town Hall meeting room on the lower level at Tysons Corner, when a member will describe experiences in growing roses in Africa. Admission is free, and non-members are welcome.

It's nice to be able to enjoy tree-ripened peaches and apples from your garden, but planting the trees is not all that's invloved: It's just about impossible to grow these fruits today without their being attacked by insects and diseases. Some of these may be present in damaging numbers every pear, others only from time to time.

Spraying to protect the trees and their fruit may not be necessary in a particular year-you may be able to get a lot of fruit without spraying-but you can never be sure of it. Commercial growers spray their apple trees 12 or more times during a season. The fruit is kept almost continually covered with a film of pesticide to kill attacking insects before they can damage the fruit.

Gardeners can harvest a lot of good fruit without spraying that often, but it is important to spray regularly at the right time with an effective material, to spray thoroughly, and to keep it up throughtout the season. Skip just one spray and all your effort may go down the drain. It's much easier to spray dwarf trees than the large standard ones, and your chances of success are much greater.

For gardeners who want to spray, specialists say the best bet is to use one of the all-purpose fruit sprays, which combine insecticides and fungicides. They are available at large garden centers under several brand names, such as Ortho Home Orchard Spray, Acme Fruit Tree Spray, etc. Directions on the label for use and application should be followed closely. You'll need to make an application about every 10 to 14 days.

For those who do not want to spray, it's important in late fall to remove all loose bark on the trunks of trees to prevent insects from wintering there. If fruit falls to the ground during the growing season, pick it up and destroy it. You'll need to collect dropped fruit of early-maturing varieties two or three times a week and late-maturing ones once a week.

The most destructive of the insects includes apple maggot, also called the railroad worm; coddling moth; the half a worm and you wondered where the other half was, and plum curculio, which over-winters as a adult under debris on the ground near the tree.

Raising apples and peaches can be a lot of fun when you get yourself organized on how to do it, so don't let the bugs spoil it.

Q-How deep should Irish potato seed pieces be planted? I get conflicting advice-some say only two inches, others six inches.

A-Many potato growers believe they are in a race against time to get the potato sprout up in the sunlight before the seed piece rots. Because of this they plant their seed two inches or less below the soil. However, three years of research at the Ohio State University has shown that planting the seed pieces at a depth of six inches results in higher yields, and adding two inches of water per week until they come up has no yield effect on deep planted seed. Sunburn, a common problem, is reduced considerably by the deeper planting.

Q-After tomatoes form on the plant, how long does it take for them to ripen?

A-The time to maturity of vegetables depends on variety characteristics, temperature, rainfall, amount of sunshine, soil fertility and location.Tomatoes usually mature in 30 to 45 days, snap beans 7 to 10 days after the blossoms appear, cucumbers for pickles 4 to 5 days, slicing cucumbers 14 to 18 days, summer squash 5 to 6 days, and winter squash such as Hubbard 11 to 12 weeks. Sweet peppers usually take the same time as tomatoes to mature to the green stage and another 15 days to turn red. Sweet corn matures 18 to 24 days after the silk appears. Hot and dry weather always speeds up maturity.

Q-Two of my young pines have some kind of white stuff in the joints. Is it anything I should do something about?

A-It probably is a white mass of waxy filament secreted by pine bark aphids. Spraying with spectracide (diazinon) usually is effective. Directions on the label should be read and followed closely. Lady beetles and other predaceous insects generally take care of pine bark aphids and spraying may not be necessary.

Q-We have a sweet cherry in our yard, and a wild cherry. Would it be possible to graft a cutting from it to the wild cherry tree?

A-Yes, it may be possible, but every wild cherry tree is different and the graft or bud may not take on all of them. The only way to find out about your tree is to try it.

Q-I live in a high-rise and would love to grow some tomatoes and herbs on my windowsill. Is it practical? I can give them a southern exposure with sunlight most of the day.

A-Cocktail tomatoes, small peppers, radishes and almosts all of the herbs used in cooking can be grown in pots on a sunny windowsill. Actually, the only limit is the amount of space available that gets adequate light.

Q-Are the tops of rutabagas good to eat?

A-They are flavorful and nutritious if harvested while young. As they get older they become tough, fibrous and too strong in flavor.

Q-When planting trees and shrubs this spring should I remove the burlap from around the ball of dirt?

A-No leave the burlap around the ball of soil. It will keep the rootball tight and protect the root system from being disturbed. If wire is holding the burlap in place, remove it. The burlap will decay in a short time. One other suggestion: never pick up a balled and burlap plant by its top branches; pick it up by the rootball instead.