Late Fall Weed Control: It’s Not Too Late to Reduce the Thistle Population

Mild weather followed by a frost has landowners wondering if weeds like thistles, poison hemlock and plantain can still be controlled this time of year.

“Thinner grass stands coming out of a major drought along with adequate moisture this fall has created an ideal environment for weeds to develop that will impact our pastures and hayfields for many years if they are left unchecked,” said Tim Schnakenberg, agronomy specialist with University of Missouri Extension.

Until the area gets consistent cold weather in the low twenties or lower with visible cold effects on the plants, Schnakenberg recommends continuing to spray these weeds.

“Many of these biennial and perennial weeds that are still healthy are tolerant of cooler temperatures and will respond to chemical application on mild fall days. A demonstration we did on a farm in northeast Stone County several years ago in November using the product Milestone on thistles showed excellent results,” said Schnakenberg.

Many of the herbicides registered for these problem weeds will work as long as we have had consistent high temperatures in the fifties or higher and sunshine for several days in a row.

Schnakenberg recommended herbicides for thistles include: 2,4-D, picloram and 2,4-D products (eg. Grazon), Cimarron, Tordon and GrazonNext.

Products for poison hemlock include picloram and 2,4-D products and Tordon.

Buckhorn plantain can be more challenging and requires higher rates of 2,4-D, GrazonNext and the picloram and 2,4-D–type products.

“If you don’t deal with them now or early next spring, these problems will only get worse and reduce the available grass for grazing or hay on fields,” said Schnakenberg.

For more information, contact either of these MU Extension agronomy specialists in southwest Missouri: Tim Schnakenberg in Stone County, (417) 357-6812 or Brie Menjoulet in Hickory County, (417) 745-6767.