Monterey Lawn & Garden Products recently received California registration for Star Thistle Killer. This product contains the same active ingredient, Clopyralid, and the same concentration as the product Transline, made by Dow Agro Sciences. It is now available for use on farm and ranchette pastures or by homeowners and does not require a permit. It not only controls star thistle but also Musk thistle, Canada thistle, and Knapweed. There are no grazing restrictions with this product.
According to the University of California star thistle infects 10-15 million acres in California. It is poisonous to horses causing a nervous disorder called "Chewing disease" which can be fatal.
Star Thistle Killer is both a preemergence and postemergence herbicide. University of California recommends application between January and March for best results. Later application may require a higher rate. Grasses are tolerant to Star Thistle Killer but clovers and alfalfa will be injured.
Star Thistle Killer is packaged in a 8 oz container. The usage rate is up to ¼ fluid oz (1½ teaspoon) in 2 gallons of water per 1,000 sq feet. In California, do not apply over ¼ fluid oz per 1,000 sq ft. At the maximum rate, the 8 oz bottle will treat ½ acre.
Star Thistle Killer will be made available through local nurseries, garden centers, and hardware stores. For more contact Monterey Lawn & Garden, P.O. Box 35000, Fresno, CA 93745, phone: 559/499-2100, fax: 559/499-2113, or www.montereylawngarden.com.