Pasture weed control

Now is a good time to control musk thistle and other biennials in pastures. Success often depends on herbicide application while the plant is in the rosette stage, prior to bolting, because biennials are more difficult to kill after the stem begins to elongate. Several options are available that will provide acceptable control of musk thistle, including:

  • 1.5-2 quarts 2,4-D,
  • 1 quart 2,4-D + 0.5 pint Banvel,
  • 0.2-0.3 ounces Ally, and
  • 6-8 ounces Tordon 22K + 1 quart 2,4-D.

Many products registered for use in pastures have restrictions concerning haying or grazing, which should be considered prior to product selection (see table). Most perennial weed species will not reach an appropriate growth stage for treatment for several weeks.

While herbicides occasionally are needed to manage specific weed problems in pastures, promoting vigorous growth of the pasture grasses should be the foundation of the weed management program. Many weed problems are due to overgrazing, poor fertility programs, or other management problems. Eliminating the cause of the problem, rather than treating the symptom, should be the focus of weed management.

Grazing and haying restrictions for pasture herbicides.

Herbicide Rate Lactating dairy Beef and nonlactating dairy
Grazing Hay harvest Grazing Hay harvest Slaughter1
Ally 0.1-0.3 oz. 0 0 0 0 0
Banvel 1 pt. 7 days 37 days 0 0 30 days
Banvel 1-2 pt. 21 days 51 days 0 0 30 days
Crossbow 1-6 qt. 1 year 1 year 5 weeks 1 year 3 days
Stinger 0.6-1.3 pt. 0 0 0 0 0
2,4-D2 1-2 qt. 7-14 days 30 days 0-7 days 0-30 days 3
Tordon 22K 0.5-1 qt. 14 days 14 days 0 0 3
Tordon 22K 1-2 qt. 14 days 14 days 0 14 3

1Interval animals must be removed from treated area prior to slaughter.

2Restrictions vary on 2,4-D labels. Check label of product used for specific restrictions.

This article originally appeared on page 47 of the IC-478 (6) -- April 28, 1997 issue.

Updated 04/27/1997 - 1:00pm