Adapted from Seller et al., 2019 and Dillard et al., 2019

The mention of any product is not and should not be construed as an endorsement for that product. They are included here only for educational purposes. Suggested rates are generalized by active ingredient. Specific rates will vary between products. Be sure to review teh label before application, always use the label rate, and observe grazing and haying restrictions.

Mowing can be used as a mechanical control method to reduce infestations of biennial species. Mowing can only be beneficial if applied when the thistle is at the early bud growth stage and before seed production. It is important to keep in mind that several mowing events per year might be needed to reduce plant populations due to maturity differences. Thistles need to be mowed as close to the soil surface as possible and multiple mowing events could help root energy reserves of perennial thistle species and help prevent seed production. Mowing persistence and proper timing will be important factors for cultural control of thistle species. Fire as a control tool can be erratic and should be used to reduce biomass and increase herbicide coverage.

Several herbicides can be used for thistle control (Table 1). Before considering the use of any herbicide it is important to read the label and pay attention to grazing and haying restrictions associated with the applicate rate. Biennial thistles should be treated in the late fall or early spring since seedlings that emerge in later summer will not bolt in the winter but remain in the rosette stage. Biennials are most susceptible to herbicides in the rosette stage. Early control is very im- portant because a long-term eradication can be challenging due to the large among of seeds produced. On the other hand, chemical control of perennial thistles should occur in the summer or fall when they are at or beyond the bud stage of growth, but before flowering.

Summary – Uncontrolled, thick thistle stands can reduce grazing potential, lower nutritive value, and impact livestock performance. A single plant can produce enough seed to increase the opportunity for greater thistle populations the fol- lowing year. Effective control practices must be implemented before flower formation. If you think you do not have this- tles, scout your fields from mid-spring to late fall to determine populations and prevent new infestations. Although there might be different thistle species in your pastures, they could be closely related, and control recommendations could pro- vide a broad-spectrum benefit.

Upcoming Events

February 19, 2021—Alliance of Sustainable Farms Virtual Field Day.
March 19, 2021—Cool-season Forage Field Day, Starkville, MS
March 26, 2021—Coastal Plain Forage Field Day, Newton, MS
March 29, 2021—Alliance of Sustainable Farms Field Day, Piney Woods School, Piney Woods, MS

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