DATE: Sunday, April 20, 1997                TAG: 9704180095

SECTION: HOME & GARDEN           PAGE: G5   EDITION: FINAL 

COLUMN: GARDENING 

TYPE: Q & A 

                                            LENGTH:  171 lines

NO EASY CURE WHEN WILT KILLS TOMATOES

When we moved to Virginia Beach a decade ago, I dug up sod, imported black soil, set up landscape timbers and created a small garden on the sunny side of our house. For three years, I had fine tomatoes and vegetables. Then my wife wanted a spot for an herb garden. A passing trucker hawked good-appearing black soil, scraped from the top of a new developement, he said. After I filled the herb bed, I had some soil left and added it to the older garden plot.

My tomato plants zoomed to 6 feet high and were covered with blossoms and small fruit. I anticipated a bumper crop. Instead, the plants turned yellow, drooped and died. I took one to the county extension agent who said the plant was infected with Southern Bacteria Wilt.

The county agent recomended I move the garden, not an easy thing to do without usurping our small front lawn. Is there any other reasonable cure for this frustrating condition? The herbs, rosemary, thyme and other non-fruit-bearing plants seem to cope with the disease.

William M. Traupel, Virginia Beach

Herbs can live in almost any well-drained soil. Never buy soil from a truck driver going up and down the road. That's an invitation to get ripped off.

You have Southern Bacteria Wilt, just as the county agent told you. It may or may not have come in with the black soil you bought. There is no chemical that will cure it, although Vapam will do a partial job. Vapam is not currently sold to homeowners, but some remains on shelves and you might find it in a feed and seed store.

The only known cure for wilt, according to experts at the Hampton Roads Research Center, is to sow the area with a cover crop, such as rye grass. Or use buckwheat, soybeans or alfalfa, because they are legumes and will restore some nitrogen to the soil. Four years of this process is usually required to clean the wilt from your soil. Sorry, but a lot of gardeners have this same problem. The cure is slow and difficult.

My question pertains to Christmas cacti. I thought they had to be kept in 12 hours of darkness during daylight hours to bloom. I have two that are kept year around in our family room that faces south. They get sunlight from sunrise until sunset every day, as long as the sun is shining. We even have skylights that provide more light.

Last year, I put them in the bathroom cabinet during the day and brought them out at night. I had a few blooms that Christmas. This year, I meant to put them in the cabinet but forgot. One day I was going to put them away but noticed buds on one of them, so left them where they were. I had a ton of blooms on one and the other is full of buds.

Should I keep the plants out again next year? I'm also wondering what to do with poinsettias that I have from last year that still have red petals on them. Will they turn red again?

Lynda D. Wise-Stielow, Portsmouth

Your letter proves again that Christmas cacti are temperamental. What works for one person doesn't work for another. The only reason I would know that caused yours to bloom so well is that you keep that room at a low temperature, particularly at night. Cactus set buds when in total darkness or exposed to cool conditions. The easiest method is to put them outdoors in summer and keep them there until late in the fall, when they should have set buds.

I would do nothing different in the future. I'm sending you some bulletins on Christmas cacti, so you can read what university experts say.

As to your poinsettia, it needs to go outdoors in summer and be kept in darkness in the fall for 14 hours per day if you expect red bracts for Christmas.

Can you identify the enclosed tree leaves and tell me what type tree it is? I dug it off my lot in southwest Virginia in the Blue Ridge mountains when it was about 1 foot tall. My next door neighbor said it was a dogwood, but I don't think so. It grew nearly 9 feet in one year.

Carl Prevatte, Chesapeake

Bonnie Appleton and Laurie Smith at the Hampton Roads Research Center say it's definitely not a dogwood. Your envelope did not contain a whole leaf on a stem, which is usually needed for positive identification.

Dan Milbocker, who is the best plant identifier I know, said: ``The tree is white ash, Fraxinus americana. It is native to the eastern United States. Leaves of the sample are actually leaflets, but most ash species have narrower leaflets. White ash generally has broader leaflets than other species but not as broad as these. But there is considerable variation in leaf type of white ash. I have seen both narrow-leafed and broad-leafed types, such as the sample. I am fairly certain that the sample leaf is from a white ash.''

Where can I find a fan-tail willow tree? I want one where the branches curl and appear to grow together, forming wonderful flower arranging pieces. I have heard they can be transplanted if anyone has a seedling they might share. I'll appreciate any help you can offer.

Abby Baird, Norfolk

My wife is an expert flower arranger and uses a lot of corkscrew willow (Salix tortuosa) because we have two trees of it. It roots easily in water. She has some dried fan-tail willow, which I know flower arrangers love, but for which I do not have much admiration. Donald Wyman's book, ``Trees for American Gardens,'' does not list fan-tail willow. Anyone interested should make note of its proper name, which is Salix Sachalinensis, cultivar Sekka. Bonnie Appleton at the Hampton Roads Research Center came to our rescue and found two sources: Forestfarm, 990 Tetherow Road, Williams, Ore. 97544-9599. Call (503) 846-6963 or (541) 846-7629. Its catalog costs $3. The other source is Windrows, 1093 Mill Road, Pen Argyle, Pa. 10872. Call (610) 588-1037.

Those interested in sources for unusual plants should purchase ``Taylor's Guide to Specialty Nurseries'' by Barbara Barton (Houghton Mifflin Co., $16.95 paperback).

Enclosed is a bloom and a few leaves from a plant that grows outside the Circuit Court building in Norfolk. It appears to be in the azalea family. Please tell me its name and a nursery from which I might buy plants. When is the best time to plant it?

Hope W. Pierce, Norfolk

The sample bloom and leaf look like Rose Bud azalea. Its flowers look like small roses. Local nurseries usually carry this azalea. Fall planting is best, but you could plant in the spring. If you can't find plants locally, try some of the specialty azalea nurseries such as Cardinal Nursery, Route 1, Box 316, State Road, N.C. 28676 (catalog free) or Transplant Nursery, Parkertown Road, Lavonia, Ga 30553 (catalog $1).

I've had my Christmas cactus for more than 25 years with few problems. Last fall it started giving off tiny granules, a sample of which I am enclosing. The table under the branches is covered with them. During the past year, an old branch dried up and died. Are the two phenomena connected? I don't see any sign of infestation. Can you assist in diagnosing this problem?

Mary Ann Pezzullo, Duck, N.C.

Yours is a real puzzler. First, entomologist Peter Schultz, director of the Hampton Roads Research Center, examined the samples under a microscope and determined they are not insects. Then Cash King, owner of Flowers by Kings in Virginia Beach, looked at the sample and said he'd never seen anything like it.

Finally, Virginia Tech's Bonnie Appleton surmised that the flecks are pollen, dropping from the blooms. Why the plant would drop pollen this year and not before is a puzzle. It should not affect the health of the plant. Appleton says the older limb dropping off was probably due to age.

I have quite a few American boxwoods on my property that have become very large, because they're 34 years old. Is it possible to cut them back and not harm them? If so, when is the best time of year to prune?

Amsbry Mitchell Brooks Jr., Virginia Beach

You can prune boxwood anytime except late summer and early fall. Pruning then might force new growth. Winter is an ideal time, because many people want boxwood for Christmas greens. The important thing is to prune the plant naturally. Do not give it a crew-cut. Reach down into the plant and take out entire limbs to reduce height and still have the plant look natural.

I have some evergreen bushes in my yard. When fall comes, they get some kind of white substance on them that makes them look like they have a disease. I would like to know what it is and what I can use to spray them.

Ruth Clark, Portsmouth

The white substance is most likely powdery mildew. If it's happening late in the season, when growth has stopped, you need not worry. It should be gone by spring. The other possibliity is that it is scale or powdery mildew and scale. The only way to make sure is to clip a branch and mail in for positive identification.

The spray to use is horticultural oil, used in the fall and again in early spring.

When do I trim or cut back my pussy willow tree? It is a big bush now. Also when do I trim my sweet bud (or sweet Betsy as we called it in North Carolina when I was growing up)?

Mary Johnson, Chesapeake

Bonnie Appleton, Hampton Roads' tree authority, says to prune pussy willow after flowering, which would mean spring. She says if you cut it back in the fall, you would lose next year's bloom buds. Pussy willow is short-lived in this area. Most people don't get more than three to five years growth from them, at best. I've given up, although I admire the plant.

As to your Sweet Betsy, it goes by many names, but it's proper name is Clethra. It can be pruned anytime except late summer. MEMO: No gardening questions will be taken over the phone. Write to

Robert Stiffler, The Virginian-Pilot, 150 W. Brambleton Ave., Norfolk,

Va. 23510. Answers will be published on a space-available basis. For an

earlier reply, send a self-addressed, stamped envelope.

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