Mature impatiens can suffer from stem rot as well as damping-off

Backyard Q&A

In The Garden

June 27, 2004|By Jon Traunfeld & Ellen Nibali | Jon Traunfeld & Ellen Nibali,Special to the Sun

For several years, my mature impatiens have been dying suddenly from what appears to be the damping-off disease that seedlings usually get. The stem blackens at the soil line, falls over and dies. We have tried using different containers, locations, soil, and suppliers.

Mature impatiens can be infected with a stem rot, similar in appearance to damping-off, caused by a variety of soil-dwelling fungi. A bacterial wilt can also cause impatiens to rot suddenly at ground level and fall over. To distinguish the bacterial wilt, cut an infected stem and look for a yellowish ooze.

Either way, prevent these stem rots by avoiding the environments in which they thrive. Use well-drained soil or potting mixes, don't overwater or crowd plants, and keep mulch back from the plant stems. Remove and dispose of infected plants, plus surrounding soil (if in containers). Keep the area free of dead plant debris. To prevent spreading the disease with your garden tools, disinfect with 1 part bleach to 3 parts water or 70 percent alcohol.

This past summer, we lost several Leland cypress trees to bagworms. When is the best time to spray and what do you suggest that we use?

Bagworms are the larval or caterpillar stage of a moth. They construct the bag for protection while they feed. They also pupate into moths inside the bags. Their eggs hatch in early June -- with each bag holding up to 1,000 eggs. Handpick new bags made by the emerging caterpillars to break their lifecycle. Dispose of them (drowning in a bucket of soapy water does the trick). Do not throw bags on the ground.

If you have a good sprayer, you can also spray the trees with an insecticide containing Bt, or Bacillus thuringiensis. It's a safe, organic insecticide. Bt must be applied when the caterpillars are small, between June 15 and July 15. You can buy it at hardware stores or garden centers.

I have mushrooms abounding in my new sod. There are single ones with an inverted, cone-shaped head and also groups that don't rise above grass height. I sprinkled lime pellets on them, but it hasn't stopped them. The area was previously lined with trees. They died due to house construction. I had the trees removed and the stumps ground down below the soil line.

Many mushrooms appear with wet weather. The spores blow in and mushrooms pop up where never before seen. Most are temporary. There is no fungicide labeled for mushrooms. In your case, you may also have mushrooms, or fungi, growing on the decaying tree roots in your soil. You can knock them over if you like. The easiest approach with mushrooms is to enjoy them as the curiosities or fleeting phenomenon they are.

Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at the University of Maryland Cooperative Extension's Home and Garden Information Center. The center offers Maryland residents free gardening information and answers to plant and pest questions. Call its hot line at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail questions to www.hgic.umd.edu. (You can also download or order publications and diagnose plant problems online).

Checklist

1. Handpick and squish the pests that are feeding on your flower and vegetable plants. Check the underside of the leaf!

2. During dry weather, it's better to water most plants deeply a few times a week rather than a little bit each day.

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