Weed management is very important for maintaining pasture productivity and lower production cost. One needs to be very watchful to identify the emerging weeds in pastures and apply an appropriate method or adopt the integrated management technique on time to avoid weed infestation.
Whichever method is used, weeds should be controlled when they are young and still in the vegetative stage. Once seeds are dropped, more weeds will come up in the next season, resulting in a waste of money and time spent for weed control. If weeds are not controlled, they gradually take over a pasture since the grazer selects against them.
Weed pressure in pastures can be a challenge. Discussions among participants in pasture walks often center on weed control ideas.
Mike Gehl, a grazing specialist with the Milwaukee River Watershed, pointed out that weeds can actually be nutritious for livestock, but the animals will not eat them if there are more tasty species in the area. When he leads pasture walks, he shares ideas for weed control, including establishing the right mix of legumes and grasses in order to fill in bare spots where weeds would otherwise grow.
Some graziers have tried ways to get their cattle to eat weeds. One way is to pick the leaves of the weeds for about a week and feed them to the animals in the bunk to help them get accustomed to them. The idea is similar to the theory about inspiring children to eat new foods. It takes eating something seven times before the person develops a taste for it.
Another method is to cover the weeds with a coating of molasses in the pasture for about a week to get the animals to eat the weeds.
Still other graziers use mob grazing as a strategic tool for weed control. It also helps with a more even distribution of nutrients and some believe it improves soil health.
A University of Wisconsin study of mob grazing as a tool for weed control revealed that mob grazing is not simply moving a big group of cattle frequently from one tall forage pasture to another along with rest periods between grazings. Those who employ that method say it is more complex than that.
People who have tried mob grazing say cattle seem to eat everything that is out there, including weeds, whereas in a traditional system, they leave the weeds alone.
Mark Renz, weed specialist at UW-Extension, worked with a graduate student on researching the results of mob grazing on Canada thistle, a problem weed in Wisconsin pastures.
Initially the researchers did not notice a benefit to mob grazing when it came to thistle presence, but after two years, there was some evidence of an impact.
Among those participating in the UW grazing survey regarding the use of mob grazing as a strategy, 70 percent indicated that the even distribution of nutrients was a more important benefit of mob grazing than weed control.