By Ted Wiseman, OSU Extension, Perry County (originally published in The Ohio Cattleman)
Maintaining high-quality pastures is crucial for Ohio’s beef producers. Weeds compete with forages for nutrients, water, and sunlight, potentially lowering the quality and quantity of the forage available to grazing livestock. Weeds can significantly impact pasture quality and even cause livestock health issues if poisonous species are consumed. Traditional weed control methods include mechanical (mowing), chemical, burning, and biological controls. In 2021 we finished a three-year study focused on mechanical mowing, aiming to understand how different mowing schedules impact weed and forage growth.
In this project we had eight different treatments and were replicated four times. Treatments consisted of a Control (no mowing), mowing one time in June, July, August, September, mowing twice in June/August, July/September and mowing monthly June to September. Each plot was 15×20 feet with a one-foot border. Forage and weed samples were collected at the beginning of each month from June to September. Cattle grazed the paddock between sample collections, and plots were mowed to a height of four inches after grazing. Weights of dry matter (DM) from weeds and forages were recorded to compare the impact of different mowing schedules.
The following table shows the results for the three year average Dry Matter (DM) for forages and weeds.
Monthly mowing significantly reduced weed presence but is not practical for most producers due to time and cost constraints, it also resulted in lowest amount of forages. Mowing in June alone resulted in higher weed yields, possibly due to early canopy opening allowing more sunlight for weed growth. Ironically this treatment had more weeds than doing nothing. Cocklebur was the major weed we had in all these plots, it could still flower and produce seed regardless of treatment. Only mowing once during the season July or September effectively managed weeds and had higher forage quantity.
The location is what I would consider a typical southeastern Ohio pasture predominantly fescue, clover, and some orchard grass. Besides cocklebur other weeds included Canada thistle, Pennsylvania smartweed, horse nettle, burdock, and ribwort plantain.
There are many factors in grazing pastures that could affect how this study could compare to your own operation. But if you are battling cocklebur, more than likely you will need in include herbicides in your pasture management program.