Digging In - Advice on Eliminating Stink Bugs, Righting a Holly Tree
Thursday, January 22, 2009
Q I've had a terrible time with stink bugs in the vegetable garden, and the kids are finding them in the house. So I know they will return in the next growing season. Do you have any suggestions for getting rid of them? I've been thinking of ordering some praying mantid egg masses. If the mantids won't work, can you suggest other environmentally safe methods of destinking my garden?
A I suspect that you are referring to an insect with a long name and a short history in the United States, the brown marmorated stink bug. It is an accidental import from Asia, and its numbers have been increasing in our area in recent years. Praying mantids may kill some of them, but there will never be enough mantids to provide meaningful control. Mantids are territorial and will duel to the death with any neighboring mantids.
Stink bugs are primarily a nuisance inside the home, but they are a bane for vegetable gardeners. Indoors, they don't feed on anything during the winter, but they do emit a strong odor if disturbed. Check for gaps around windows and doors, and seal them.
This species of stink bug, which feeds on a wide variety of host plants, is most damaging to fruit and vegetable crops. Green beans, peaches and raspberries are most affected, in my experience. The insects are particularly damaging to raspberries because their scent renders the berries inedible.
The best way to control them outdoors is to destroy their eggs, which are yellow and massed in groups of 20 to 30 on the undersides of leaves. Check for them weekly from mid-spring through early summer. Hatching nymphs can be controlled with insecticidal soap.
The adults are difficult to control. In commercial apple orchards, a pesticide containing kaolin clay has been used to prevent feeding injury, but the clay must be washed off the fruits at harvest. In the home garden, handpick any bugs you find. When autumn arrives, clean up the garden to deny the bugs and their eggs winter shelter. Thorough weeding in spring will also reduce their habitat. Stink bugs often start feeding on weeds and then move into vegetable crops as the season progresses.
I have an eight-foot holly tree that needs to be replanted because it is leaning too much. When would be the best time to do this?
Instead of uprooting the holly, you may be able to right it with a rope attached to a metal stake. After several years, it should remain vertical on its own. This is the best option if your plant is mature and well established.
If you planted it recently, it would be best to dig it up and replant it. Do this in March or early April. It may have tilted because the soil on the side opposite the lean was too compacted or wet to allow good root development. If that is the case, make sure when replanting that the roots are loosened and that soil conditions are corrected in the new site.
Scott Aker is a horticulturist at the U.S. National Arboretum.