Last summer, I had an agronomist in the Dakotas tell me some of the farmers in his area were spending more than $100 per acre on herbicides and still not controlling waterhemp!!
If you have kochia or waterhemp on your farm, here is how you stop those weeds for a lot less than $100…
PRE-PLANT $12 to $22
Yup. You’ve got to spray before you plant. That is, if you want to get by for as little money as possible AND achieve great control. If you skip this step, your odds of spending a lot more money are high. Here are the products:
- YELLOW (Trifluralin in conventional-till or Prowl in no-till)
- PLUS METRIBUZIN
- PLUS VALOR OR AUTHORITY
Perhaps the biggest question we get about our recommendations here is, “Why shouldn’t I use a Group 15 like Warrant, Outlook, or Dual instead of a Yellow?” Yellows are better on grass and almost all broadleaves vs. Group 15’s. Plus, you don’t use Yellows in corn, so they’re great for reducing resistance issues.
What ramps up the cost the most in this program is if you are in no-till or strip-till, since Prowl is about $8 per acre more than Trifluralin, but Prowl does not need to be tilled in. The second component is Metribuzin. Metribuzin has a lot of ability to stop tough broadleaves, which is why metribuzin should almost always be a part of your soybean weed control program. However, if you have sandy soil and low organic matter, don’t use metribuzin, as it can cause some crop safety concerns.
The third item on the list is the most important. Use Valor or Authority or a premix that contains one of these PPO’s. These herbicides have tremendous activity on waterhemp, kochia, Palmer, lambsquarters, ragweed, and a host of broadleaf weeds.
EARLY POST $10 to $21 including adjuvants
- GROUP 15: Zidua, Warrant, Outlook, or Dual
- PLUS PPO: Flexstar or Cadet
- PLUS VOLUNTEER CORN HERBICIDE, IF NEEDED
- PLUS ROUNDUP, IF NEEDED
We don’t always use a Group 15 and a post-emerge PPO on our farm, and you don’t have to either. Do this in your weediest fields (or where you absolutely can’t have a single weed left) or in conventional soybeans (minus the Roundup).
If you have volunteer corn coming up but don’t want the Group 15 or PPO for extra residual, we recommend spraying a volunteer corn herbicide early in the season, possibly even by itself or with Roundup. Volunteer corn is a bad yield robber. Plus, when you don’t stop volunteer corn by early June, it hosts corn rootworms and can lead to much higher rootworm counts next year. The most popular product here is Anthem Maxx, which contains the active ingredients from Zidua and Cadet.
MID-POST $7 to $18 including adjuvants
- LIBERTY
- AND/OR ENLIST ONE
- AND/OR ROUNDUP
- PLUS VOLUNTEER CORN HERBICIDE, IF NEEDED
If you have conventional soybeans, your only remaining options for waterhemp and kochia are listed in the “Late-Post” category. If you have XtendFlex or Enlist soybeans, you have much, much better choices, which are listed here. With Liberty, Enlist One, and Roundup, you obviously have to have soybeans tolerant to those herbicides.
LATE-POST $7 to $9 including adjuvants
- COBRA
- OR ULTRA BLAZER
- OR CADET
- OR RESOURCE
None of these herbicides are great on a wide spectrum of broadleaves, but they all have activity. I like Cobra the best for waterhemp and kochia. Cadet and Resource are lights-out on velvetleaf. Ultra Blazer isn’t too bad on pigweed and some “oddball” weeds like buffalobur. None of these herbicides are very expensive, but they are all PPOs and will give your soybeans a little bit of leaf burn.
SUMMARY
You certainly don’t have to do all four steps unless you have very high weed pressure. Also, if you plant your soybeans in 7- or 10-inch rows, you will have quicker and more complete crop canopy, which means less need for herbicide. Regardless of what you decide for an overall program, we strongly recommend starting with the 3 Pre’s that I listed first. That one step alone will get you 95%, season-long weed control in most cases in my experience, and the cost is not bad at all.
Speaking of cost, even if you did all four steps at the low-end cost, you’ll invest just $36. At the high-end cost for each section, involving tankmixes and higher rates, you’ll end up at $70 per acre – but like I say, I would only do this in very weedy fields and kind of as a last resort. Realistically, you should only need to invest $25 to $35 per acre in most fields to keep them pretty weed-free this season.