By Darren Hefty
What are the toughest weeds in pastures and how do you control them? One thing’s for sure, the pasture weeds vary as you move across the country (in fact, you may not recognize some of these names). As you can imagine, our recommendations for control vary, as well. Here’s my best run at some of the toughest weeds in pastures. Keep in mind, labels vary around the country, so always read and follow label directions.
Thistles (including Canada, Bull, and Musk) – with lots of residual, Milestone is the best product to use. Typically we’re running 7 ounces for Canada thistle and 5 ounces for bull or musk. Combination products like Chaparral (Milestone + Ally) and ForeFront (Milestone + 2,4-D) are fairly effective, but not as good as straight Milestone. Tordon is very good, too, and has come way down in price over the last few years.
Leafy Spurge – Tordon is by far the best. It takes at least a full quart to make a permanent difference wiping out spurge. 2 quarts per acre is the maximum rate and would be the best when spot spraying patches. One note on Tordon is that if you use over 1 quart per acre, you’re not supposed to graze the land for 2 weeks in those areas or cut them for hay during that time. Also, be sure to keep Tordon away from fish and from trees you don’t want dead.
Hoary Cress (Whitetop) – Since it chokes out the grass anyway, most people run 3 quarts of 4 lb. Roundup (or the highest labeled rate allowed) and kill everything in the patch. This is effective, but if you want a chance at saving the grass, you should run with Telar at one ounce per acre. Killing it in the fall is typically the best, but if you catch it in the pre-bloom stage, it is quite vulnerable then, as well.
Larkspur – Tordon at 2 quarts/acre. Brian hates it when I say things like this, but this is a very pretty plant. Hopefully you never see it flower out, but if you do, I think you’ll agree with me. Kill larkspur in the rosette stage before flower bud formation for best results. Tall larkspur requires the full 2 quarts. Other larkspurs like geyer and plains may only require 1 pint of Tordon for control.
Sagebrush – 3 ounces of Chaparral + 2/3 quart of LV6. Tordon works well too at 1 pint/acre plus 2/3 quart of LV6.
Houndstongue – Chaparral at 2.5 to 3.3 ounces/acre. You can add 2/3 quart of LV6 if needed, but going to the higher rate of Chaparral may be better.
Common Mullein – Tordon at 1 pint/acre plus 2/3 quart of LV6 is good. So is 2.5 pints of ForeFront or 3 ounces of Chaparral.
Spotted Knapweed, Absinth Wormwood – Tordon at 1 quart/acre or 7 ounces of Milestone.
Russian Knapweed and Dalmatian Toadflax – These weeds are really tough. We’ve had the best luck with Tordon at 1 to 2 quarts/acre (I’d suggest staying toward the higher rate). For the Russian knapweed, Chaparral at 3 ounces is pretty good, too.
Club Moss – 1.5 pints of Tordon + 8 ounces of LV6
Multiflora Rose – Tordon at 1 to 2 quarts/acre plus either 1 quart/acre of Remedy or 1.67 quarts LV6.
Western Ragweed – Tordon at 1 to 2 quarts/acre or 1 quart/acre of ForeFront have been the most popular choices.
Dandelion – People who don’t have dandelions laugh and think this can’t be that tough. They’re wrong. The highest labeled rates of Distinct (6 ounces/acre) or Banvel (1 quart/acre) have worked fairly well.
The optimum timing for control of each of these weeds will vary somewhat, but in general the best times to kill them are either in the fall 1 to 3 weeks before the first hard-killing frost or when they are actively growing during the spring and summer. For spring and summer control, stopping these weeds before they put seed on is the most effective and beneficial.