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Don Kinzler, Published September 06 2013

Fielding questions

Q I try to grow tomatoes with little success. I buy quality plants from local greenhouses with 60-65 day fruiting. All tomatoes grow to about 2 feet tall, set flowers and produce about four fruits, which then stop growing when the size of golf balls. Wildflowers grow perfectly in the same area. My garden is surrounded by trees from adjoining lots on two sides. Any thoughts would be appreciated.

– Leo Lantz, Fargo

A It sounds like you are doing everything right by starting with good local plants. Tomatoes are best planted in open, full, all-day sun with no overhanging trees or shade. Six hours of sun is a bare minimum. Many types of wildflowers are more tolerant of shade. Most tomato varieties do well in large containers which can be located elsewhere in full sun if the garden spot is too shaded.

Q Help! Our older elm tree has the seasons mixed up. It has been dropping yellow leaves all summer long. It is one of the few elm trees left in Kindred, N.D., because most were removed due to Dutch elm disease. It is very tall and gives great shade. What are the symptoms of Dutch elm disease? Is there any prevention?

– Joan Halland, Kindred

A The classic Dutch elm disease symptoms are wilting, drooping, yellowing, curling leaves on one or more branches. Leaves then turn brown and remain on the tree. If the tree is infected late in the summer, the leaves will droop, turn yellow and drop prematurely. All symptoms are accompanied by brown streaking in the sapwood seen by peeling the bark of infected twigs.

Because it sounds like the leaves began turning yellow and dropping earlier in the season rather than later, I don’t think the symptoms sound like Dutch elm disease, but rather environmental stress from a late cold spring that turned into a hot and dry midsummer.

There is no practical prevention for Dutch elm disease, other than removal of infected trees to prevent spread. Water your tree well extending out to the dripline to encourage health. There are several other elm foliage diseases but no practical control on large trees.

Q In the last two years the leaves on my peonies have a dusty looking coating. Is it something from the river water I use? I’ve used the water many years and just noticed it lately.

– Andrea Abraham, Horace, N.D.

A The gray, dusty coating you described has been very common this year. It’s a powdery mildew and is frequently seen on the leaves of peonies, roses and lilacs.

It is a fungus disease that begins during periods of high moisture and humidity as we experienced during the first part of our season. Garden fungicides and disease preventers containing chlorothalonil are effective, but must be applied as preventatives before the symptoms are seen.

Powdery mildew rarely causes death, but makes foliage less attractive. After peony tops have been blackened by frost, cut back to ground level and dispose to reduce over-wintering of the fungus organism.

The river water you are using isn’t to blame.

If you have a gardening or lawn care question, email Don Kinzler at ForumGrowingTogether@hotmail.com. Questions with broad appeal may be published, so please include your name, city and state for appropriate advice.