War on Weeds—weeds are everybody’s problem

Quackgrass (Elytrigia repens) is a rhizomatous perennial that spreads by seeds and rhizomes. Quackgrass is a highly competitive agricultural weed which can significantly reduce crop yields and reduce the value of seed grain crops through contamination. In addition, quackgrass can infest lawns, gardens, roadsides, ditches, and any disturbed moist areas. It is a rapid invader that can stabilize eroding soils but will take over good areas for other plants. Quackgrass is known to release allelopathic toxins into the soil inhibiting the growth of other plants.

Quackgrass grows 1 to 3 feet tall, its stems are thin with swollen nodes. The ½ inch wide leaves are rolled, blue green in color, and clasping around the stem, have a hairy upper surface and a waxy lower surface, and near the tip, have a band-like constriction. They have a dense fibrous root system with large rhizomes that allow for rapid spread. The seedhead is composed of flattened seeds arranged alternately up the spike inflorescence. Usually awnless, they may have very short lawns.

Integrated Pest Management (IPM) Options:  

Prevention – A healthy lawn will outcompete quackgrass and reduce the likelihood of its establishment. Increased nitrogen fertilizer and mowing can help establish a healthy lawn. Applying a mulch layer 3 inches deep on planting beds will help reduce seed germination. 

Mechanical – Effective control must target both above ground and below ground plant structures. Cultivation or tillage is not a good option since cut rhizomes will continue to grow. Hand pulling plants prior to seed maturity can reduce plant populations.

There are several chemical control options available for use, for more information visit https://pnwhandbooks.org/ then search “Quackgrass” in the weed section. Select the appropriate option. Always read and follow herbicide label directions!

Tom Jacobsen, University of Idaho Extension Educator in Fremont County. (208) 624-3102 [email protected]