Q I propagate African violets for my own enjoyment and sometimes I notice some dusty mold-like material on the undersides of the blooms. I tried spraying with an anti-mildew spray but it was nearly fatal. When I pick off the blooms, some of it falls onto the leaves. Is there any other solution to the problem? J.T.
Darien, Conn. Q I have a begonia plant that desperately needs help. All the leaves develop a white powder on them, then they dry up and fall off, leaving the bare stems. I keep the plant indoors for the winter, water it once a week, and give it afternoon sun.
Pen Argyl, Pa.
Both plants in question have powdery mildew, a fungus that affects many houseplants in areas where there is poor air circulation.
Although you can dust them with one of the houseplant fungicides from a garden store, the problem will continue unless you provide good air circulation. We have a small fan running constantly on our enclosed porch and a large fan in our greenhouse. They do the trick. The spores (which are common where atmospheric conditions support them) are kept in suspension by the fans until they dry up instead of lighting on the plants, where they start to grow.
We suggest you keep a small fan going, not directly toward the plants, but just off to an angle. Some African violet growers tell us they clear up mildew by using a diluted solution of one part household bleach to 12 parts of water. Invert the plant by holding firmly to the pot and root ball, then swish plant around in the solution. Do this early in the day so they can dry off before nightfall. Gently blot off any large droplets. We have tried this method and found it works fine, but we suggest you try it on a few leaves first. Some varieties are more sensitive than others. A fan should still be used in all plant areas where there is not ample air circulation. Never set African violets in direct sun.
Q Every year we have a bed of zinnias. Last year it included Zenith Hybrid (cactus type), Cut and Come Again, and some Burpee's Bouquet Hybrids. We have a similar selection this year, plus some from seeds which we gathered last fall from the Zenith Hybrids. From these seeds, we were surprised to have only a few cactus types. The rest were a mix of sizes and types which did not resemble Zenith. Can you explain?
Terre Haute, Ind.
If you sow the seeds of hybrid varieties it is only rarely that you will get a plant that resembles the parents.
Also, if several varieties are planted close together, they are likely to be cross-pollinated by insects and wind so that even nonhybrids would not reproduce exactly.
Whether dealing with flowers or vegetables, commercial breeders must go to great lengths to prevent any accidental cross-pollinating. Hybrid seeds are more expensive because of the labor and expertise involved, but their increased vigor and flowering capacity make them well worth the investment.
Q When I was a child, we had in our home garden an onion that we called ``multiplier onion.'' It was similar to size and use to a green onion, and it grew in a clump gradually increasing in number by dividing, much as chives do.
For several years we've been trying to find this onion. Most garden store personnel have never heard of it. Our neighbor gave us a type that develops little bulbs at the top instead of seeds, but this one is not like the one I am thinking of.
Can you suggest a source? Someone told me what we want are called ``bunching onions.''
Bodega Bay, Calif.
We have the one you speak of that has bulblets on the tops, but we also have one called ``bunching onions,'' which are referred to as Welsh onions. Both are perennial types. Two sources which may be of help to you, although we cannot guarantee they have the ones you are thinking of, are: Jeff McCormack, Southern Exposure Seed Exchange, Box 158, North Garden, VA 22959; J.L. Hudson, Seedsman, PO Box 1058, Redwood City, CA 94064.
Q We have a large Gravenstein apple tree on which we have had no apples for the past few years, while apple trees in a farmer's pasture has abundant crops. What can we do to get a harvest? We also have some four-year-old dwarf trees that have not produced.
If you have the proper pollinators for your dwarf trees, give them another year. You did not say what varieties they are, nor if you have a suitable pollinator tree for the Gravenstein. Since Gravenstein is sterile, it will not pollinate itself, nor other varieties, therefore you must have a variety to pollinate it. Mutsu (now Crispin) and Jonagold are also sterile. Good pollinators are Golden and Red Delicious, Jonathan, and Cortland.
For others, check with your state experiment station or your nurseryman. Other factors for lack of fruit could be wet weather at pollination time or cool temperature (65 degrees F. or below), so bees cannot work.
If you have a question about your garden, inside or out, send it, along with a self-addressed, stamped envelope, to the Garden Page, The Christian Science Monitor, One Norway St., Boston, MA 02115.
Doc and Katy Abraham are nationally known horticulturists.