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Purple loosestrife is on both the Quarantine List (meaning commercial sale is prevented in the state) and the High Priority Watch List for Kansas.

Some weeds cause problems by out-competing native vegetation and reducing crop yields. Let's forget about dandelions and crabgrass, even though they can be annoying. The weeds I am talking about are designated as noxious or described as invasive by the Kansas Department of Agriculture.

Noxious weeds are defined by law as having one or more of the following characteristics: being aggressive and difficult to manage, parasitic, a carrier or host of deleterious insects or disease, and being non-native, new to, or not common to the United States or parts thereof.

Most of the 14 weeds defined as noxious by Kansas law are more common in pastures and unmanaged land in residential lawns and gardens. Field bindweed and Johnsongrass, however, are two noxious weeds that are common in the landscape.

Field bindweed is a perennial vine with roots that can extend up to 30 feet. Besides sprouting new stems from the long roots, the plant produces seeds that are carried by birds and other animals, lawn mowers, road machinery, farm equipment, livestock (and manure), and drainage water. Portions of bindweed roots also travel to new homes on tilling equipment.

The funnel-shaped white flowers and twining stems of bindweed might be attractive to someone who is unaware of the plant's hardiness. Even the deep green leaves, which grow in a variety of shapes up to two inches long, are deceivingly appealing.

In lawns and gardens, the Kansas Department of Agriculture recommends hoeing or mechanically removing bindweed plants every ten days to two weeks to control the plant's growth. Appropriate herbicides (organic or synthetic) can also be used according to label directions.

Johnsongrass is even more eye-catching than bindweed, but mostly because it is bigger. The plant looks a lot like the ornamental grasses that are commonly cultivated for the landscape and grows to six to eight feet tall. Johnsongrass has a large, airy seedhead that is present most of the summer.

Seeds of Johnsongrass travel on machinery and livestock, and the roots are sometimes transplanted with tillage equipment. Again, hoeing, at a minimum of every 14 days, can eventually eradicate the plant from lawn and landscape areas.

Purple loosestrife, garlic mustard and Star-of-Bethlehem are additional weeds that I get a lot of questions about. Purple loosestrife is on both the Quarantine List (meaning commercial sale is prevented in the state) and the High Priority Watch List for Kansas. Both lists can include insects, diseases and plants that are considered serious threats to native and cultivated plant populations.

Purple loosestrife is three to four feet tall and shrubby with spiky pinkish-purple flowers. It was sold as a desirable landscape plant until officials realized its ability to establish and choke out other plants in Kansas wetlands. Homeowners who have purple loosestrife in their landscapes are not required to remove it, but should be aware that the plant can cause problems in the right environment.

Garlic mustard is described as invasive but is not on the noxious or priority lists. The biennial is blooming right now and is most easily identified by its erect stems, triangular leaves, and narrow pods that appear after flowering. Garlic mustard varies in height from 12- to 42-inches tall and the leaves release a garlic-like odor when crushed.

Star-of-Bethlehem is in the same class with dandelions and other common diseases. Although these plants may re-seed, break off when you try to pull them and keep coming back despite your diligent efforts, they are really just a nuisance.

For identification and management of Field bindweed, Johnsongrass and/or other noxious weeds, samples can be brought to the Douglas County Extension office, 2110 Harper. Master Gardeners and I can help with management in lawns and gardens, and Agriculture Extension Agent Bill Wood can help with management in pastures and cropland.

• Jennifer Smith is the Horticulture Extension Agent for K-State Research and Extension in Douglas County. Contact her or an Extension Master Gardener with your gardening questions at 843-7058.

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