Q. Some mustard greens and broccoli raab overwintered in our garden. I forgot to pull them up and let them flower and go to seed. Can I save these seeds and plant them in the fall?
A. If both varieties were open-pollinated (nonhybrids), you can save the seeds. Cut the seed stalk when the seed pods begin to open, revealing the hard, black seeds. Sow the saved seed every two to three weeks starting in late August for an extended fall harvest.
Q. I have a large Siberian elm tree in my back yard that seems to be healthy except for the fact that the bark looks and feels wet at the crotch of each branch and even along the trunk. Is this natural?
A. Slim flux, also known as bacterial wetwood, is a common disease of elms. The oozing is unsightly and may have a foul odor, but is not life threatening. Otherwise healthy trees can live a long time with slim flux. There are no treatments or control measures for the disease.
Q. I see aphids on my spirea, foxgloves, cabbages and other plants. I usually don't worry too much about them but there are tons of them this year. Should I spray with an insecticide, or try buying and releasing ladybugs to control them?
A. It usually is not necessary to spray insecticides or release beneficials to control aphids. Aphid numbers start out high in the spring, but populations of ladybird beetles, green lacewings and wasp parasites build up quickly to keep the pests in check. You'll see these predators and parasites at work if you observe the aphid colonies closely.
Planting a wide variety of flowering plants that bloom throughout spring and summer will help attract and keep beneficial insects in your landscape. If you feel it necessary to destroy the aphids you see, an application of insecticidal soap or ultra-fine horticultural oil will do the job.
Garden tips are provided by the Home and Garden Information Center of the Cooperative Extension Service of the University of Maryland. For additional information on these questions, or if you have questions of your own, call the center's hot line at 800-342-2507 or visit its Web site at www.agnr.umd.edu/users/hgic
This Week's Checklist
Put tropical lilies out in backyard ponds. Most varieties require a minimum of five to six hours of sunlight each day.
Prune evergreen trees and shrubs by pinching off half of new growth.
Pick off and destroy insect egg masses you find on vegetable plants. Look carefully at the upper and lower leaves.
Pub Date: 5/31/98