ASK THE GARDENERS. Q & A

March 18, 1986

Q For several years, I have had a bountiful crop of raspberries, without spraying, from my small patch. However, the past two years, there have appeared dark circles on the ends of the canes. Soon the top part above the circle would break off. I presume it is some kind of borer but don't know how to cope with it. I never miss the garden page and will appreciate your help. A. C. A. Mashpee, Mass. You have a problem with raspberry cane borers, long-horned beetles that sometimes damage roses and azaleas also. The slim, yellow and black striped female makes a double row of punctures around the tip, then lays eggs between these girdles. The tip soon wilts; the grub hatches in summer and bores down about two inches into the cane. The next season it bores the length of the cane before pupating. The best control is to continually inspect canes. Cut all those that are dead, then watch for wilting tips during summer. Cut six inchess below the wilted tip. Destroy all affected canes and tips so grubs and pupae cannot escape. Adult beetles are easily handpicked. Q I have many outdoor (perennial) violet plants which produce lots of blooms. I love to give little bunches to my friends, but they seem to wilt so quickly. How do I keep the blossoms looking nice and perky? V. M. M. San Luis Obispo, Calif.

Violets, with the exception of those grown in greenhouses especially for corsages, are not noted for their keeping qualities. Like pansies (also violas), they last only a day or two. However, the following will help: Cut stems as long as possible with a sharp knife and put them in a small jar of tepid water as you pick them. Fold a paper towel until the strip is about two inches wide, then moisten it thoroughly.

Arrange violets into bunches and add three or four leaves to ``frame'' them. Wrap a section of towel strip around stems, and tuck each bunch into a litle vase or fruit juice glass. Add more water and then put in a cool place for about an hour before taking the little vases to friends. Q Could you please give me some pointers about growing Crown-of-thorns? Just as the plant gets full of buds they drop off. Sometimes leaves drop off also. M. G. Bremerton, Wash.

Sometimes folks are tempted to think of Crown-of-thorns as a form of cactus, hence they let it get too dry. This will cause buds to blast and leaves to fall. Bud drop can also be caused by overwatering, low temperature, and low humidity.

Well cared for, this relative of the poinsettia (both Euphorbia) can give a beautiful show most of the year. They like a sunny window, temperature between 60 to 72 degrees F., and a soil that is uniformly moist at all times.

You can help increase humidity by setting the plant on a pan of pebbles with water reaching just to the top of the pebbles. A good soil mix is: one part each of coarse sand, peat moss, and garden loam, plus one-half part of perlite.

If you have a question about your garden, inside or out, send it to the Garden Page, The Christian Science Monitor, One Norway Street, Boston, Mass. 02115. Doc and Katy Abraham are nationally known horticulturists.