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MASTER GARDENERS COLUMN: What is that weed?

In one of the master gardener articles each month, I will discuss some of the many weeds that are problems in this part of Minnesota. Some will be landscape weeds, some garden weeds and others will be those you will see in ditches, fields and woods. We all have a role in identifying and controlling the weeds you encounter as you garden, care for your yard, or enjoy the woods and open spaces of northern Minnesota.

One of the weeds that has become very obvious in our landscape is baby's breath. A noxious weed in some states, Gypsiophila paniculata is an example of a plant that has spread from the cut flower industry. Baby's breath is a herbaceous perennial with a large taproot that can reach 3 feet in height. Many people like to collect it for the little white flowers on branches that make it look so airy and good in an arrangement. The odor, on the other hand, smells a little like the other end of a baby. Care should be taken when disposing of the plant material and its copious seeds. Bag it or burn it.

If you have this plant in your landscape, it is very hard to control due to its large taproot and prolific seed production. I see 40-acre fields out our way that are pure white in the summer. Frequent mowing is the only control that seems to work aside from chemical control. Small infestations can be dug; deep tilling in small areas also works.

A second nemesis, leafy spurge, has been listed by the Minnesota Department of Agriculture as the March Weed of the Month. The MDA notes in their article that leafy spurge was introduced to Minnesota in 1890 in a bushel of oats from Russia. I remember as a kid growing up near the Red River Valley that it was a universally hated weed by farmers due to its toxicity to foraging animals. Hay lands infested with leafy spurge cannot be used for animal feed.

Leafy spurge is a very distinctive plant that grows up to 4 feet tall with distinctive yellow-green flowers that bloom in June this far north. The bracts below the flowers give the appearance of petals. When mature, the plant can expel seeds up to 20 feet away from the plant. The plant has a milky sap that can irritate your skin and is toxic to horses and cattle.

Until recently, leafy spurge has been very difficult to control due to extensive underground stems and roots. Sheep and goats can reduce the spread of the weed but that is not an option for most landowners. One form of control that has been very successful is biological control. In the 1990s spurge beetles were released in parts of Minnesota as a control method and has been both successful and cost effective.

More information and photos of the plants in this articles can be found on the Minnesota Department of Agriculture website: www.mda.state.mn.us/plants/pestmanagement/weedcontrol/wom.aspx

Further information on weeds and control can be found on the University of Minnesota Extension website: www.extension.umn.edu/garden/yard-garden/

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