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In the Know about Invasive Plants

FOR IMMEDIATE RELEASE
November 25, 2013

The largest threat to maintaining diversity in our natural areas is non-native – that is, invasive – species.

These species displace native species and the wildlife that depend on them. Some of the invasive plants in Central Illinois are garlic mustard, teasel, Japanese honeysuckle, Norway maple and common reed grass. Most of these were introduced by landscapers, homeowners and natural resource area managers without knowing the consequences. Here I will highlight common reed grass.

Common reed grass (Phragmites australis) has been identified as being a widespread exotic invasive threatening prairies and wet areas throughout Illinois. Common reed grass is labeled an invasive species because it pushes out native species, decreases diversity important for wildlife and takes over disturbed sites. It's commonly seen along roadsides and in the ditches in large masses of auburn-colored plumes during the latter part of summer. Its beauty disguises its aggressive qualities.

This grass spreads by underground structures known as rhizomes and can spread up to 10 feet within one growing season. The grass reaches up to 15 feet, blocking out all the sunlight from native plants. The lack of native species is detrimental in that exotic species can't support wildlife.

To control common reed grass, the University of Illinois recommends a combination of mowing, herbicides and prescribed burns. These should be done in the late summer to early fall after seed production. Most eradication programs start off with an herbicide treatment followed by a mow or a burn. Eradication can take years of effort. Take care when using pesticides not to get them on non-target plants or near water, and read the label before use.

Additional landscape species to avoid planting in your garden are butterfly bush, Japanese barberry, Norway maple, common privet, tree of heaven, black jet bead and the very popular burning bush. All have shown invasive qualities and are escaping into our natural areas.

Alternatives to popular non-native ornamentals are productive natives like high bush blueberry, nannyberry viburnum, cherry, oak leaf hydrangea, nine bark, witch-hazel, and red osier dogwood, which can provide valuable food and shelter for birds

Source: Kelly Allsup, Extension Educator, Horticulture, kallsup@uiuc.edu