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December 14, 2013

1 - Some winter weeds look like dandelions, and like dandelions they must be managed.

Yard and Garden December 14, 2013

Q.

Before all this snow came and covered the ground, I saw plants that looked like dandelions. However, I remembered that there are other weeds that look like dandelions and wondered if they may be a problem. What can I do about them?

A.

There are several weeds that are common and in their juvenile stage look much like dandelions. London rocket (a common relative of mustard), prickly lettuce, and some sowthistle seedlings may be what you observed. They will survive the cold weather and can be problems in your garden next year. Some are perennial and others are annual weeds. Your local NMSU Extension Service office can help you identify these weeds and determine appropriate measures to manage specific weeds.

London rocket, a mustard weed, is a host known to overwinter curly top virus which will infect your tomatoes and chiles next year. For that reason, it is important to eliminate as many of them as possible from the vicinity of your garden (from as much of your property as possible). It is recognizable by the mustard oil fragrance of its crushed leaves. It is not prickly like some of the other weeds mentioned.

Prickly lettuce and sowthistles are in the sunflower family because they have flowers with the same structure as sunflowers, but their flower heads are much smaller. They are often prickly and when the leaves and stem are broken usually exude a milky sap. Some are annual and biennial weeds and some are perennial. This characteristic determines how you must manage these weeds. They are not as notorious as the mustards for spreading disease, but they are not good plants to allow near your garden.

With the annual weeds such as mustards, prickly lettuce, and some sowthistles the key is to remove them before they can form seeds. This may be done with herbicides, but manual removal is often fairly easy to accomplish by cutting the top from the root with a hoe or another garden implement. The mustard weeds should absolutely be removed before you plant tomatoes and chiles next spring.

The perennial weeds are a little more difficult to manage because they can regrow from a small piece of root left in the ground. Some of these weeds can have an extensive root system, so physical management by hoeing and tilling becomes more difficult, but not impossible. There are also herbicides that may be used to manage these weeds, but it is critical to use the proper product and to use it carefully according to the label direction. Your NMSU County Extension agent can help you determine the best method for managing your weeds and minimizing problems in your garden. You will also find that the book, Weeds of the West, published by the Western Society of Weed Science is a good reference for helping you identify the weeds in your garden and landscape.

For more gardening information, visit the NMSU Extension publications Web site at http://aces.nmsu.edu/pubs/_h, or to read past articles of Yard and Garden go to http://aces.nmsu.edu/pubs/periodicals.html

Send your gardening questions to:

Yard and Garden, Attn: Dr. Curtis Smith
NMSU Agricultural Science Center
1036 Miller Rd.
SW, Los Lunas, NM 87031.

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist emeritus with New Mexico State University's Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating