If you run cattle in the fescue belt, there’s a good chance fescue toxicosis is harming your herd and your pocketbook. Seedhead suppression with Chaparral herbicide is a new management approach developed by Corteva Agriscience, Agriculture Division of DowDuPont to help manage fescue’s toxic impact.

Chaparral™ herbicide provides specialized broad-spectrum weed, brush and grass management. Chaparral is the simple answer for several significant, unique needs, such as reducing the impact of toxic fescue through seed-head suppression. Best of all, when you manage fescue toxicosis with Chaparral, you also control a broad spectrum of broadleaf weeds, including winter annual weeds and other early season broadleaves — such as buttercup, poison hemlock, biennial musk, bull and plumeless thistle, wild carrot and buckbrush.

Seed Head Suppression Booklet

Q & A: Seed Head Suppression

Manage Fescue Toxicity

Learn More


Quick Facts

Tips for Success
  • Chaparral provides control of many broadleaf weeds that other herbicides miss, including pigweed, hoarycress (whitetop), buckbrush, biennial thistles (including bolted musk thistle), Missouri goldenrod, wild carrot, giant hogweed and many others.

  • Improves animal health and performance when used to suppress Kentucky 31 tall fescue seedheads.

  • Increased desirable grass production.

  • Soil residual activity controls new weeds that can emerge in multiple flushes throughout the grazing season.

  • The best and most-consistent option for clearing buckbrush.

  • Provides the best pigweed residual and blackberry control.

  • Apply 2 ounces of Chaparral™ herbicide per acre for effective weed control along with seedhead suppression.

  • Apply Chaparral as early as three weeks prior to seedhead emergence and as late as the early boot stage, with later applications preferred over earlier applications.

  • Expect a lag phase (grass yellowing) for at least two weeks.

  • Do not use liquid fertilizer as a carrier when applying Chaparral for seedhead suppression; doing so may further exacerbate grass yellowing.

  • Anticipate reduced biomass and increased forage consumption due to the reduction of seed heads and stems, and then adjust grazing programs accordingly.

  • Consider treating half your tall fescue acres or less; graze the untreated fescue up until seed-head emergence and then rotate to the treated fescue, which will remain vegetative through fescue’s summer slump.

  • Remember: Research shows reduced biomass is offset by increased livestock gains.


two cows
Only a fence and herbicide treatment separate these two calves, but there’s a big difference in their health.
The slick calf on the left grazed fescue treated with Chaparral herbicide;
the calf on the right with the longer hair coat grazed untreated fescue.

Summary of the effect of endophyte-infected tall fescue on cattle‡

Performance Metric

Effect on Production

Pregnancy rates
Decreased 15 to 40 percent
Milk production
Decreased 25 percent
Weaning weights
Decreased 65 to 85 pounds
Time spent grazing
Decreased 20 percent
Forage intake
Decreased 25 to 40 percent
Average daily gain
Decreased 0.3 to 1.2 pounds per day
Water usage
Increased 25 percent
Body temperature
Increased 1 to 4 degrees

Stockers benefit from fescue management.

Effect of seedhead suppression on stocker cattle and forage quality of pastures grazed. Data was collected from 2009 through 2012 on three separate studies conducted by the USDA-ARS Forage Animal Production Unit.¥

Treated with Chaparral™ herbicide

Nonsuppressed seed heads

2009 to 2010
Steer ADG
2.1 pounds
1.48 pounds
Crude protein
14.4 percent
11.6 percent
In vitro dry matter digestibility
78.6 percent
71.7 percent
2011 to 2012
Steer ADG
2.1 pounds
1.74 pounds
Crude Protein
14.2 percent
9.9 percent
In vitro dry matter digestibility
72.2 percent
66.4 percent
2013 to 2014
Steer ADG
2.9 pounds
1.96 pounds
Crude Protein
18.6 percent
14.8 percent
In vitro dry matter digestibility
76.1 percent
72.6 percent

Toxic fescue impacts weaning weights and pregnancy weights.

Effect of seedhead suppression on 205-day adjusted weaning weights of calves and breed back of cows.


205-day Adjusted Weaning Weight

Cow Pregnancy Rates

Farm 1
473 pounds
418 pounds
+55 pounds
95 percent
80 percent
Farm 2
483 pounds
463 pounds
+20 pounds
95 percent
70 percent
Farm 3
476 pounds
459 pounds
+17 pounds
Equal at 91 percent

Data was collected from three different locations owned by Whitesell Land and Cattle Co. At each location, the pastures were split into two paddocks so that half the herd would be on a paddock treated with Chaparral™ herbicide (tall fescue, seed heads suppressed), and the other half would be on a paddock treated with GrazonNext® HL herbicide (nonsuppressed seed heads).