Native Nebraska pasture plants such as Tall, Platte (prairie), Flodman, Yellowspine, and Wavyleaf (gray) Thistles can be beneficial for butterflies and provide seeds for songbirds. However, many ‘nonnative’ Thistle species such as Musk, Canada, Plumeless, Bull and Scotch are ‘Noxious Weeds’ that must be controlled depending on your Nebraska county. These nonnative thistles can cause significant grazing losses as they become aggressive competition for desirable pasture grasses and can spread rapidly.
For pastures with noxious weed thistles, now is the time for Spring herbicide applications while the plants are still in the short rosette to bolted growth stages prior to flowering. Our Extension EC-130 “Guide for Weed, Disease, and Insect Management in Nebraska” publication provides a cost comparison of labelled thistle noxious weeds control products.
For musk and plumeless thistles, the highest control rated Spring control herbicides include: Chaparral®/Opensight®; Dicamba or 2,4D ester + Dicamba; Milestone® and Transline®.
Other labelled products include: 2,4-D ester; Cimarron Plus®; Curtail®; Grazon P+D; Redeem R&P; and Telar®.
Canada Thistle is a perennial; therefore, fall control is the preferred time for herbicide applications. So, during Spring and Summer, it is recommended to prevent seed production by mowing once in June and again in July along with applying inexpensive herbicides like 2,4-D (2 quarts per acre) or tank mixed dicamba and 2,4-D. Then, after the first fall frost; but before the ground freezes, apply a labelled fall herbicide. Spring labelled Canada Thistle products include: Graslan L®; Method®; Grazon NXT; Chaparral/Opensight®; Tordon 22K or picloram 22K; Escort® or Cimarron Plus®; Wide Match®; Milestone®; or Transline®.
As always, read and follow product labels. For best Spring control success, all herbicides must be sprayed in rosette, pre-bud to early Spring flowering stages. After flowering, hand rogueing (using a hoe, corn knife or shovel) OR mowing of flowering stalks are your remaining thistle control options.
