QUESTION: I have cabbage, collards, tomatoes and beets in my little garden spot. The little green worms are eating my cabbage and collard leaves, and I don't know what to do about them. I dread thinking about those big tomato worms.
--W.C., Santa Monica
ANSWER: Let me introduce you to Bacilus thuringiensis Var. kurstaki, or BT, as it is usually called. When eaten and digested by caterpillars, this bacteria kills them in about three days, and it can be applied to vegetables up to the day of harvest because it is not a poison. It does not affect humans, pets, earthworms, the beneficial predators in your garden or the soil.
BT works best when caterpillars are young, so apply it thoroughly and before you see damage (though it will help even after you see lots of holes).
It kills cabbage worms and tomato horn worms, though it doesn't work on tomato worms once they get big, fat and sassy. You'll have to handpick these (or hire some neighborhood child to do it for you!).
I like to use the dust version of BT (made by Safer) because I can see it on the vegetable and know whether it has been washed off by rain or watering. Because it requires no mixing, it's always ready to use when I need it.
I keep cole crops like cabbage and cauliflower dusted from Day 1, so there is never a chance for the worms to get started.
To use Safer's dust, hold the plastic bottle upside down, remove the small plug that's set off to one side, and then gently squeeze, aiming the little nozzle up so it covers the undersides of leaves (where the worms are). I've been told that the dust is hard to find at nurseries, though the liquid form of BT is commonplace.
That white butterfly (the European cabbage butterfly) fluttering around gardens right now is the adult of the worm and is busy laying this winter's eggs.
An interesting tidbit: Cabbage worms prefer green cabbages over the red varieties, perhaps because the green worms are not invisible against the red leaves. Red cabbage also looks prettier when shredded into salads.
Pruning Coral Trees Cuts Into the Blossoms
Q: Last spring, I was passing the Beverly Hills Hotel and noticed all the coral trees flowering. I have three of these trees of the same size planted about 10 years ago and regularly cut them back and am still waiting for some flowers. What could be the problem?
--E.N., Beverly Hills
A: Cutting back Erythrina caffra each year will keep this coral tree from flowering because all the growth that makes flowers is being removed. It is possible to thin them, leaving some of this flowering wood, but even doing this is going to cut way back on the flowering.
If they must be pruned, do it right after they flower (or when they would flower if they could, usually in March). All that pruning probably means the trees are too big for their spot in the garden, so maybe a smaller flowering tree would be a better choice.
Too much water and fertilizer--as when they're planted in a lawn or in a heavy clay soil--also can stop them from flowering (all they do is grow new leaves). The best-looking coral trees I've seen were growing on an unwatered, rocky slope in Malibu. They were small and compact and flowered profusely. This is one tree that shouldn't be watered, at least in summer.
New Growth Can Alter Flavor of Citrus Fruit
Q: I am writing to ask about a recent development with our lemon tree. It has borne lemons for many years, but last year we noticed a change in the fruit, which now look like tangerines and taste like a very sour bitter lemon. The current fruit is orange and the rind is just like one would find on a tangerine.
--R.M., Los Angeles
A: Fruit can't change that radically, say from a lemon to a tangerine, but it can "sport" and this new growth can be slightly different from the old. That's how new varieties of things like lemons come to be.
This growth, especially if it's stronger, could have outpaced the growth of the lemons so it seems like the tree has suddenly changed.
More likely, the rootstock of the lemon has taken over. Citrus are usually grafted to another kind of citrus' roots--some type of citrus that is tough but not tasty--so the plants are stronger, more disease resistant, more cold tolerant or for some other reason.
At one point in time, lemons were grafted to a mandarin called Cleopatra, but the practice was discontinued because the Cleopatra rootstock tended to outgrow the lemon. Other common rootstocks for lemons include Troyer citrange, rough lemon and Citrus macrophylla.
If suckers coming from the rootstock are not broken off, they can rapidly outgrow the grafted top, so instead of a lemon, you may now have one of the near-wild rootstocks. The fruit you describe could be the fruit of the rootstock, perhaps the Cleopatra mandarin.
Catalogs Can Spice Up Pepper, Tomato Choices
Q: I love growing tomatoes and peppers, but most nurseries out here in the Santa Clarita Valley seem to only carry the common or generic varieties. Can you recommend any nurseries in the north county that carry the exotics? Could you recommend any comprehensive books on growing some?
A: I don't know of any nurseries in your area that specialize in uncommon vegetable varieties, but there are mail-order sources for exotic peppers and tomatoes.
I just received an interesting catalog called the Pepper Gal, P.O. Box 23006, Fort Lauderdale, Fla., 33307-3006, (954) 537-5540. It lists more peppers than I thought existed, but you'll have to start them from seed next spring.
The Tomato Growers Supply Co., P.O. Box 2237, Fort Myers, Fla., 33902, (941) 768-1119, stocks seeds of hundreds of tomato varieties.
These two seed companies also carry many books on peppers or tomatoes.
If you want plants, you'll have to keep searching the nurseries; they do have more interesting fare every year. For seedlings of heirloom varieties, you can mail-order them from Santa Barbara Heirloom Nursery, P.O. Box 4235, Santa Barbara, CA 93140, (805) 968-5444. They are on the Web at www.heirloom.com/heirloom
Questions should be sent to "Garden Q&A;" in care of the Real Estate section, Los Angeles Times, Times Mirror Square, Los Angeles 90053. Please include your address and telephone number.