Kill the weeds without harming the birds

Question:

What can be done when wild birds are feeding in a gravel yard that has grown weeds this summer as a result of our monsoon rains? I don't want to use chemicals for fear of harming the birds. Is there any way to kill the weeds without harming the birds?
- G. F.
Deming

Answer:

You have some non-chemical options for weed removal. The first is manual removal by pulling or cutting the weed. Since the landscape has rock mulch, a mower cant be used but a line trimmer can be used. Wear protective clothing (long trousers, goggles, and a dust mask) when cutting weeds in this manner. After cutting, some weeds will grow back, but they may be easily cut again while the new growth is young and tender. It is probably too late to prevent seed development in some of the weeds in your lawn, so cutting will only remove those there now. A supply of weed seeds will have fallen into the rocks to provide a new crop of weeds when there is adequate moisture in a future summer season.

Use of a propane weed torch will kill some of the seeds that have formed, especially if they are still on the plant. Seeds under the rocks will probably survive. The torch may more thoroughly kill weeds that will then exhibit less regrowth than the weeds that are cut. When using a torch, be sure to consider whether or not it is allowed in your community. Also, remember that damaging heat extends farther than the flame from the torch. Plants beyond the flame can be damaged. There is also a risk of damaging structures and paint on those structures or other items in the landscape. Keep any flammable materials very far away from the torch.

After cutting, pulling, or burning the weeds, remove them from the landscape. Raking will scatter seeds remaining on the seed heads, so picking them up by hand and putting them into a garden cart or garbage bags will reduce the seed supply waiting for future monsoons.

Since you preferred not to use chemicals, I saved discussion of herbicides until the end in the event other readers wanted to use them. There are some herbicides with low toxicity for birds and mammals. (Read the label to determine which herbicides to use.) These may be used, but at this time of year will probably not prevent seed maturation. Use of preemergent herbicides next year may help reduce future problems, even in rock landscapes. These preemergent herbicides act by killing the seeds as they begin to germinate and are not effective once the plants have begun growth.

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Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

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