Musk thistle (Carduus nutans L.) is a serious weed found in pastures, roadsides, conserva tion reserve acres, and other noncultivated areas across Iowa. This weed infests more than three million acres in the state. Because the state of Iowa classifies musk thistle as a noxious weed, landowners must control any plants of this species present on their property. It is estimated that Iowa farmers spend more than $5 million annually to control musk thistle. Currently, the primary control method for musk thistle involves the use of herbicides
