Those outlaws of the plant kingdom are at it once again, riding roughshod over pasture productivity, plundering sunlight, water and nutrients needed by your forages.

Cool nights in March and April delayed the annual onslaught of pasture weeds but those warm May days unleashed a frenzy of annual weeds like ragweed, bedstraw, curl dock and sunflower.

“A lot of people are going to have some pretty heavy weed infestations in pastures this year,” says Gary Kilgore, agronomic consultant and former Kansas State University Extension crops and soils specialist.

For cool season pastures such as tall fescue, now is the time for a herbicide application, he asserts. For annuals that are no more than six inches tall, the old standby 2,4-D LVE, is a good choice at a rate of one pound per acre of the actual ingredient—either a pint or a quart, depending on the formulation.

If you’re going after perennials or some of the tougher annuals like lanceleaf ragweed, producers have several good options, according to Kilgore.

Grazon P+D, which is 2,4-D plus picloram is one route to take and the agronomist’s other suggestion is one pound of 2,4-D with 12 ounces of Banvel (or Clarity).

A third option is Range Star, which is 2,4-D plus dicamba, at three pints per acre.

Keep in mind, Kilgore warns, that, Clarity and dicamba could eliminate desirable clovers in the pasture. Annual lespedeza, he adds, will tolerate the herbicides at lower rates—about a half pound, or pint, per acre.

A new product from Dow, Milestone, at five to six ounces per acre is effective on broadleaves as well as being a good choice for controlling musk thistles prior to heading.

Another Dow product, Redeme R+P, which includes triclopyr—the active ingredient in Remedy, is particularly effective on weeds which mature a little later on in the season.

And Crossbow, triclopyr and 2,4-D, is a good general use herbicide similar in control to Grazon P+D.

For warm season pastures, producers have essentially the same arsenal of products, Kilgore says, but he suggests that they shouldn’t be applied until June.

The products work well, Kilgore notes, but proper timing is the all-essential “other” ingredient. In general, you want to hit the weed right after it’s fully leafed-out. The problem is that different species leaf-out at different times.

“You have to pick your target because optimum timing to spray is going to depend on what you’re after,” Kilgore says. “If it’s buckbrush you’re after, now’s the time. A pint and a half to two pints of 2,4-D actual per acre would just be perfect. It’s too early for sericea, though, and if you wait until the time is right for the sericea, you’re going to injure your buckbrush but you probably won’t kill it.

“My advice is to pick a target species for year one and go after it. In year two, redefine that target and adjust your timing for whatever primary weed species you’re after. There are trade-offs. You will get control on weeds besides your target but controlling all of your pasture weeds with a single application just isn’t going to happen.”