Q: Last year beetles ruined my lima beans. They are showing up again this year. What can I use to save my beans?

A: The Mexican bean beetle is a serious pest of garden and field beans and soybeans. Both young and old feed on the foliage, usually on the undersurface. The leaves are skeletonized. With heavy infestation, pods and stems also may be attacked. The greatest damage usually occurs in July and August.

The recommended treatment in the home garden in spraying or dusting with Sevin. Follow directions on the label for application.

Applications should be made late in the day to avoid injury to bees as much as possible.

Q: The leaves on my Bartlett pear tree are turning black (specimen enclosed). Can you tell me what the problem is and how to take care of it?

A: This is fire blight, a bacterial disease that can be serious on pear, some varieties of apple, flowering crabapple and quince trees. Bartlett, Bosc and Clapp Favorite pears are very susceptible while Seckel, Kieffer and Anjou are somewhat resistant.

Leaves of infected twigs wilt and turn dark brown to black. They appear as if scorched by fire. The disease spreads to twigs and branches and may even go down to the roots. Young trees may be killed in one year.

New growth is very susceptible, old growth is more resistant to infection. Any condition, such as heavy nitrogen fertilization or heavy pruning, which encourages a lot of new succulent growth increases susceptibility to infection.

Blighted twigs and branches should be cut back. The cut should be made 6 to 8 inches below the point of visible infection. Sterilize the pruning tool after each cut with a solution of 70 per cent denatured alcohol.

There is no chemical control available that is practical for a few trees growing in the garden.

Q: I have very poor drainage in my backyard and apparently can do very little about it. Drainage pipes won't work because there is no place for them to drain to. Is there an alternative that will permit me to grow a few vegetables?

A: A raised bed, 6 to 9 inches in height, may take care of the drainage problem. Bring in soil to make the bed and hold it in place with concrete or logs.

Few flowers and vegetables will grow in soil with poor drainage. The soil stays wet too long after a rain and plant roots do not get enough oxygen.

Q: How do you prune a Bourbon rose? I planted one a year ago and now it has five 7-foot canes. I searched rose books at the library and they told how to prune hybrid teas, floribundas, ramblers and everthing but Bourbons.

A: The Bourbons, such as the silvery pink Zephirine Drouhin with its heavenly fragrance, should be pruned as little as possible. The object of pruning is to remove dead wood and to permit each stem to get full sunlight.

Each healthy cane should receive as much sunlight as possible. If one branch shades another, the least desirable should be removed.

Q: When is the best time to prune rambler roses? Mine have not been pruned for several years and the flowers are not very good.

A: Ramblers roses, the climbers that bear small flowers in clusters, such as Dorothy Perkins, should be pruned every year soon after they finish blooming in late spring or early summer. In this way, new canes are produced which provide next year's flowers.

Mild pruning is the general rule but always prune and new growth brings new flowers of quality. Long unwieldy canes should be removed. Always make the cut on a slant, clean and sharp.

Cut the old canes back to a young, healty side branch. Some canes may be cut back almost to the ground, others half way. The idea is to get rid of old wood that does not contribute to flowering, and give new growth a chance to develop in its place. It is better to prune late in the season than not at all.

Q: What cabbages do you recommed for fall planting?

A: Savoy King Hybrid is one of the best for both spring and fall crops. It matures in 90 days. Ruby Ball Hybrid, an All-American winner, with heads of dark red color, delicious both cooked and raw, is also very good for both spring and fall. It matures in 68 days.

If a branch grows toward the center of the plant, remove it to prevent it from shading or interfering with other branches. In other words, prune to keep weak branches from bothering stronger ones. Each branch to bloom its best needs plenty of sunshine and air.

Canes that are too tall can be shortened in late fall but don't take too much.

Q: My young maple tree has too many branches. When is the best time to remove some of them?

A: The best time to do the pruning is when the tree is dormant, between late fall or early spring. Usually, it is best to leave these branches on the tree as long as possible because the leaves privide food for the tree and the tree will grow faster. They can be left on a few years until they start to get rather large.

Q: Birds are ruining my peaches before they are ripe enough to pick. Can I pick them early and let them ripen indoors?

A: Peaches are best if allowed to stay on the tree until they start to turn soft. Tree-ripened peaches gain as much as 300 per cent in quality during the last few days of maturation. Once they are picked, peaches do not gain additional flavor or sweetness.

A peach with whitish, yellowish or golden ground cover is nearly ripe. It is at this stage they are usually picked for sale at roadside stands.

Peaches picked a little early will turn soft and have some flavor if kept in a cool place out of the sun. They won't be nearly as good as those that ripened on the tree, but much better than none at all.