Late fall weed control

Wednesday, November 7, 2012

Mild weather followed by a frost has landowners wondering if weeds such as 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 down the road if they are left unchecked", according to Tim Schnakenberg, agronomy specialist with University of Missouri Extension based in Galena.

"Until we get into consistent cold weather in the low 20s or lower with visible cold effects on the plants, my recommendation is to continue 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."

Many of the herbicides registered for these problem weeds will work as long as we have had consistent high temperatures in the 50s or higher and sunshine for several days in a row.

Schnakenberg recommended herbicides for thistles including 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.

Schnakenberg emphasizes, "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."

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