Nashville, Tennessee, USA
January 31, 2017

It’s not often you can implement a single practice that delivers two topline benefits across your cattle operation. But that’s exactly what an early spring application of Chaparral™ herbicide can bring: Effective weed control that grows more low-cost forage and fescue seedhead suppression for fewer toxic effects.

Seedhead suppression can provide the starting point for more effectively managing fescue toxicosis. Alkaloids produced by the endophyte concentrate in the seedhead at a rate five times higher than in leaves or stems. Reducing or eliminating those seed heads can help decrease the incidence and severity of fescue toxicosis.

“Research across the fescue belt shows that an early spring application of Chaparral controls a wide mix of broadleaf weeds and prevents most tall fescue plants from developing seed heads,” explains Scott Flynn, Dow AgroSciences field scientist. “By suppressing seed heads to prevent their consumption, Chaparral helps mitigate fescue toxicosis in beef cattle grazing operations.”

Toxins in tall fescue peak in the seed head when the seed head is most palatable (generally mid- to late June). The period of highest concentration does not coincide with the visible symptoms of fescue toxicosis because of the toxins’ residual effects. Animals consume high concentrations in the spring and then suffer from heat stress when the effects are exacerbated by high summer temperatures, resulting in a cascade of effects (see table).

Apply Chaparral as early as three weeks prior to seed head emergence and as late as the early boot stage, with later applications preferred over earlier applications. This keeps the plants in a high-quality vegetative state, while taking infested seed heads out of the grazing picture.

When applications of Chaparral™ herbicide are timed for optimum seedhead suppression, they will control winter annual weeds and other early season broadleaves — such as buttercup; poison hemlock; biennial musk, bull and plumeless thistle; wild carrot; and buckbrush — says Pat Burch, field scientist with Dow AgroSciences. “The residual control Chaparral provides will control several species that emerge after application, including ragweed, cocklebur, chicory and horsenettle,” he says.

Appropriate expectations
Just as producers can expect to see a difference in the appearance and performance of their cattle when they effectively manage fescue toxicosis, they can expect to see a change in their pastures, too.

“The early application timing somewhat intensifies the effect Chaparral has on certain grass species, including tall fescue,” Flynn says.

“Producers will note grass yellowing, which can last at least a couple of weeks,” Burch adds. “However, tall fescue that has been treated with Chaparral for seedhead suppression remains leafy and maintains forage quality longer through the season.”

Because most seedhead production is suppressed, plants won’t produce stems — resulting in a noticeable change in the appearance of tall fescue pastures and a reduction in pasture biomass.

“The good news is the lost biomass is mostly unpalatable stems and toxin-laden seed heads,” Burch explains. “Removal of the toxins can help improve the appetites of grazing cattle. Producers likely will need to re-evaluate stocking rates.” A rotational grazing program can help boost forage utilization.

Research trials show that improved per-head gains due to removal of endophyte-infected seed heads offset the reduction in carrying capacity. Additionally — depending on weed pressure — the positive forage response to the removal of weedy competition may offset some or all of the lost carrying capacity.

In University of Kentucky trials on endophyte-infected fescue, cattle grazing pastures where Chaparral was applied to control weeds and suppress seed heads gained 0.58 pound per day more (two-year average) than those grazing untreated pastures. Stockers on fescue treated with Chaparral™ herbicide had an average daily gain of 2 pounds in two years of grazing studies.

“There is no cure for fescue toxicosis,” Flynn notes. “But using Chaparral to suppress seed heads is one of the most effective management tools available. It can be an excellent option where weed control is needed or where a simplified approach to fescue management is desired.”

For more information on using Chaparral to suppress tall fescue seed heads, contact your Dow AgroSciences Range & Pasture Specialist. You’ll find contact information at RangeAndPasture.com.

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

‡Patterson et. al., 1994
Data derived from multiple research trials where pastures contained 70 percent or more endophyte-infected tall fescue.

Tips & Pointers
Tall fescue seedhead suppression

• 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 seedhead 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

Website: http://www.dowagro.com

Published: February 1, 2017