June 2010
Featured Articles

In Your War with Pasture Weeds, Scouting and Fast Action are Critical

Ben Franklin once said, "A small leak can sink a great ship." Small weeds eventually become titanic problems for your pasture forage, if left uncontrolled. As we take a look at experts from across the country for weed control, one thing remains constant — the earlier you can detect weed problems, the better your chances of weed control.



Spot spraying is a great way to save clovers, if you have isolated stands of weeds to remove.

Scouting is the most valuable resource in the war on weeds. For instance, if you find thistle in the early stages, it is much easier to control through herbicides. In addition, if there are only a few isolated weeds, hand removal or spot spraying may be the best bet. Finally, it’s not always a given you have to sacrifice your clover stands when you spray herbicides to rid the pasture of weeds.

Weed management decisions

The herbicide 2, 4-D is used in pastures because of its low cost, ability to kill a wide range of common, broadleaf weeds and, under some conditions, has less impact on certain clovers.

It's a war on weeds. Fast action required.


"Saving clover is our biggest dilemma when spraying herbicides to get rid of weeds in pastures," said Dr. J.D. Green, weed scientist with the University of Kentucky. "White clover typically has more tolerance to 2, 4-D than red clover, but both are susceptible to potential injury."

Green doesn’t advocate spraying 2, 4-D on pastures interseeded with clover with hopes of killing the weeds and saving clover.

"The herbicide 2, 4-D poses a lesser risk to clover plants than other herbicides, but it is still a risk," Green said. "If you are going to establish clover next year, you are better off spraying herbicides that will effectively kill broadleaf weeds, and that often includes clover."

"If you want to save your annual clovers, we recommend spraying after the flower head turns brown," said Dr. Eddie Funderburg, soils and crops consultant with the Noble Foundation in Oklahoma. If there are plentiful stands of clover or other legumes, spot spraying, mowing or hand-removal of problem weeds like thistle should be considered.

Some of the cattle producers I’ve spoken with have been able to save some of their white clover when spraying. They spray 2, 4-D for buttercup and thistle in the early spring while thistles are in the rosette stage and can get a good weed kill. Some I’ve spoken with say the white clover does get stunted some, but much of it bounces back for continued growth.

Spray or mechanical removal

Check with your local Extension agent for the legalities of herbicides that can be sprayed in your area.

Pigweed has a purple shaft, needles and fuzzy seed heads.

"Troublesome weeds like horsenettle and tall ironweed can’t be effectively controlled with 2, 4-D," Green said. "Forefront, PastureGard or Crossbow are my herbicides of choice for these two weeds. Although they are not restricted use, they are, however, likely to kill clovers."

For weeds like blackberry, Funderburg recommended spraying later in the growth season during the plant’s maturity.

"In Oklahoma, we spray blackberry bushes in late June or July after they begin bearing fruit so the new wood growth will be killed," Funderburg explained. "Our rule of thumb is pick the blackberries, make a pie, then, spray and kill the plant."

Funderburg said any type of thistle should be sprayed in the early stages of growth before the plant grows the shaft or bolts the second year.

"Grazon, Cimarron Max and 2, 4-D will kill perennial and biennial thistles, if you can spray in the rosette stage," Funderburg said.

For horsenettle in Oklahoma, he recommended Weedmaster or Grazon P + D once the plant is blooming or after fruit appears.

Spot spraying

Thistle are much easier to control while they are in the rosette stage.


In many cases, spot spraying (spraying isolated, weed problem areas) can be your best option. You local Co-op carries spraying equipment like Ag Spray Equipment’s full line of sprayer tanks, nozzles and spray guns for spot spraying or complete spraying with boom-style sprayers. I find a 25-gallon Ag Spray sprayer fits perfectly in the bed of a Yamaha Rhino and the seven-foot boom sprayer is ideal for remote, rough spots. With the powerful pump, the herbicide from the spray gun reaches a distance of 40 feet according to my measurements. Visit www.agspray.com for more information.

Other options

Some cattle producers have been able to eliminate a majority of late season spraying with a hay mower. The hay mower gives a smooth clipping of pre-seeding weeds and encourages forage growth. Many have noticed how thick and relatively weed-free pasture stands are after cutting hay. The hay mower neatly cuts off weed stalks instead of knocking them over with a brush mower. For pigweed, the key is clipping the plants before production of seed heads.

Kendrick Ketchum, a beef producer in Heber Springs, AR, uses only mechanical methods for weed control. In addition, Ketchum and his three sons walk their pastures each week with shovels on their shoulders and buckets in their hands to remove isolated stands of thistle. Ketchum said other problem weeds on his farm are pigweed and buttercup.

"We try to time our mowings to clip the weeds before they produce seeds," Ketchum said.

Once the thistle bolts, the seed heads emerge and control becomes more difficult.

"In hard packed, poor areas of our land, buttercups were growing in the spring, so I began lightly disking those areas to aerate the soil, and the pasture forage began crowding out the weeds thanks to some good rain," Ketchum explained. "We can keep the problem weeds at manageable numbers on our farm without spraying, but we have to make timed-mowing and hand-removal a regular part of the work week."

According to Don Ball, Extension agronomist with Auburn University, good grazing management and optimum soil pH and fertility will help reduce weed numbers.

"This forces animals to eat weeds, and it increases the competitiveness of forage crops," Ball said. "Mowing, heavy stocking rates resulting in temporary overgrazing, mechanical hand-removal and use of goats are possibilities in certain situations for weed control."

If persistent weeds have taken over pasture forage, many of the legumes may fall victim for the pasture’s long-term forage success. You may have to sacrifice your legumes for a couple of years until the weeds have been killed. Once the weeds are under control, you can come back later to re-establish your legumes.

Your local Co-op can supply all your spraying equipment as well as herbicides for keeping weed numbers down in your pastures. Enlist the aid of your local Extension agent in weed identification, herbicide selection and sprayer calibration so your profits won’t sink this year.

John Howle is a freelance writer from Heflin.