As spring rolls in, when we look over our pastures, all we want to see is lush green grass and pretty, happy cattle. Right? Unfortunately, that isn’t always the case. Some of us may battle some unsightly weeds from time to time.
Some common nemeses may include the dreaded thistle, pigweed, lamb’s-quarters or ragweed – whereas others are battling cheatgrass, lupine, yellow star thistle and larkspur. Depending on the season and when you are grazing, some weed species may be more of a problem than others.
The first stage of the battle on weeds is knowing what you are fighting against and what weapons you have in your arsenal. Typically, in an irrigated pasture, weeds are present due to either over- or undergrazing. They can also gather along fencelines and dry corners that may go ungrazed, where weed seed can build up, or areas of disturbed soil with little competition from the pasture. In a well-managed grazing system, grasses and legumes in the pasture should be able to outcompete undesirable weeds.
However, if you’re entering a “new to you” pasture or one that has a weed infestation, you may have to take more exhaustive measures. Implementing an intensive grazing system can help even the playing field against weeds for your beneficial pasture grasses. To effectively manage pastures in this way, you typically need some portable fence and the ability to transport water or allow them to get to water in a sacrifice area.
If you don’t have enough cattle to effectively graze the pasture, you can reduce the area they are grazing in. Or, on the flip side, if you are overstocking and cattle are grazing the pasture too short, this will also increase your chances of weeds becoming a problem. Correcting these problems will allow the forages to grow and start outcompeting the weeds. Maintaining dense forage growth and good rotation reduces opportunity for weed growth.
For some of the more lethal weeds you may meet such as lupine or larkspur, it’s important to understand when during the grazing season they are most poisonous. Lupine, for instance, is most lethal in early spring when cows are in their first trimester. It is also best controlled in early spring before the bud stage. Larkspur is most poisonous early in the season and can be controlled using herbicides. Low larkspur should be controlled before flowers open but after significant vegetative growth, whereas tall larkspur can be controlled throughout the flowering stage. Weed management in a pasture is most effective early in the season before weeds have had a chance to set seed. So it is best to get on it early.
