kilgore weeds

Agronomist Gary Kilgore says many farmers and ranchers may find their pastures more heavily infested with weeds this year than they normally are.

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.”

And there are situations in which the weed problem could look worse than it is.

“If the majority of weeds in the pasture is annual common ragweed, I wouldn’t rush right out to try to control it because cattle will utilize it to some extent.

“Now if we’re talking about lanceleaf ragweed or broomweed or a whole lot of others, then, yes, spraying is a good idea.”

Kilgore stresses that it’s important to check out the label on all weed control products. Most, he notes, have a fairly limited livestock grazing interval but checking the label is a good idea.

And if you’re worried about those clouds off in the distance, the agronomist says that he likes to have about four rain-free daylight hours after application for optimum impact.

Kilgore has a couple of pet weed species that he’s particularly like to see blown to smithereens—redcedar and sericea lespedeza.

“You’ve got two shots at sericea,” he explains. “Remedy at one and a half points or PastureGuard at two pints per acre when the plants are 12 to 18 inches tall and actively growing. That’s going to be in early to mid-June.

“Your second shot at it is in the fall when the plant has open flowers. Use Escort SP at a half-ounce per acre plus a non-ionic surfactant.”

Kilgore’s strategy for fighting a sericea infestation is to spray either spring or fall in year one, skip year two and, for year three, apply at the opposite time you of year from what you did in year one.

“That gives seedlings a chance to come up and it utilizes two different modes of action in terms of herbicides,” he explains.

Easter redcedar, or, as Kilgore calls it, “the scourge of pastures throughout the area,” is often controlled by prescribed burns and that’s Kilgore’s first option.

It can, however, be controlled chemically. Tordon 22K undiluted and placed around the tree at a rate of three to four CCs per three feet of height is effective. The total rate should be divided by four and placed on each of the tree’s four sides at the drip-line. It’s also important that it not be applied when the soil is frozen or saturated because the chemical will move off-site.

Tordon 22K can also be applied in a water solution and sprayed on the foliage. One-and-a-half ounces per gallon of water should be sprayed over the entire tree, preferably between April 15 and June 15.

And finally, if you’re looking at an aerial application to control weeds and brush, Kilgore emphasizes that the amount of water used is critical. He stresses that using five gallons of water per acre consistently yields the best control.

Recommended for you