Here are THREE SIMPLE RULES we try to always keep in mind when helping you get the best weed control program in soybeans, regardless of trait.
1. USE MULTIPLE, EFFECTIVE MODES OF ACTION
2. FOCUS ON THE WORST WEEDS FIRST.
If you have a million waterhemp plants and 10 velvetleaf plants, for example, I’d probably put 99% of your effort and your dollars toward the waterhemp.
3. SPRAY BOTH PRE-EMERGE AND POST-EMERGE.
This isn’t as important in some other crops, but in soybeans it’s crucial because a number of the best and most effective herbicides in beans can only be used pre-emerge or pre-plant.
DON’T GIVE WEEDS A CHANCE IN YOUR FIELDS!
If you have followed us at all over the last half dozen years, you’ve likely heard the words, “3 Pre’s” 1000 times. I know you want to save money. I do, too. We’ve tried cutting rates, using generics, varying spray timings, and about everything else under the sun to keep our costs down, but I keep coming back to this. In soybeans, if you don’t start with the best pre-emerge herbicides on your toughest weeds, sooner or later you will question your weed control strategy. Soybean weed control is too difficult not to invest a few extra dollars per acre to get a great pre combo instead of a good one.
If you are using XtendFlex or Enlist and you don’t mind investing $20 in Liberty late in the season, you might be able to get by with only two modes of action pre instead of three, BUT IN CONVENTIONAL SOYBEANS YOU ABSOLUTELY NEED THE 3 PRE’S.
THE 3 PRE’S:
You may not have used Trifluralin (conventional-till) or Prowl (no-till) for a long time, but that’s actually great, as I expect it will give you tremendous weed control because of that. The yellows are great on grass and pretty effective on waterhemp, Palmer pigweed, lambsquarters, kochia, and many other small-seeded, Roundup-resistant broadleaves. Cost is $5 (Trifluralin) to $15 (Prowl).
This is the big one. Authority and Valor are fantastic on waterhemp, kochia, and a whole host of broadleaf weeds. They also have a little
suppression on grass. Cost is only $4 to $7 per acre depending on the rate and the product you pick.
We recommend this in all non-sandy soils. If your CEC is less than 5, definitely skip the metribuzin. If your CEC is less than 10 or if your soil pH is above
7.4, cut the rate. The full rate is two-thirds of a pound, but most people use one-third of a pound in normal soils. In the low CEC or high pH soils,
one-sixth to one-eighth of a pound is common. Cost is just $2 to $5 per acre.
EARLY POST RESIDUAL:
1. GROUP 15
My advice in most cases is to save the Group 15 for post-emerge use. In my opinion, Group 15’s are a little hard on soybeans pre-emerge. Since you likely also use Group 15’s in corn, I certainly don’t want you to spray them three times in two years. Yes, Group 15’s will bronze and slightly stunt soybeans in some instances, but that is cosmetic. If your soybeans are slightly shorter, you could see less white mold, which is a big advantage in my
region of the country. If you compare Group 15’s to yellows, PPOs, and metribuzin, the Group 15’s are definitely the worst on most Roundup-resistant broadleaves, but they are still more than good enough to include in this total program. Group 15’s are residual-only products, which is why it is good to use a contact herbicide also like the PPO’s. Cost is around $7 to $12 net depending on the product and rate you use.
Yes, you already used a PPO pre-emerge, but use another one here. I like Flexstar the best in areas where it’s labeled, as it has the longest residual and it’s the cheapest of the post-emerge PPOs. Don’t over-do it on the rate, though, as carryover can occur. If you want no carryover risk, I prefer Cadet in the early post window, but Resource or Cobra could be used instead. Cobra is best on kochia. Flexstar may be best on waterhemp/ Palmer depending on the rate, but Cobra and Cadet aren’t far behind. You can get a Group 15/ PPO combo by purchasing Warrant Ultra (Warrant & Flexstar), Anthem Maxx (Zidua & Cadet), or Perpetuo (Zidua & Resource). Cost for straight post PPOs is $4 to $10, while cost of the Group 15/PPO premixes is only $8 to $12. In other words, go with the premix.
Personally, I would avoid dicamba as much as possible. It can be added fairly safely pre-emerge or very early post. Late post, use Liberty. I know it’s roughly $20 per acre, but Liberty is a great option with no big drift potential.
I love Enlist One. We’ve seen no volatility problems, so it is night and day different than old 2,4-D. Plus, Enlist One is less than two-thirds the price of Liberty this year. Spray coverage is critical with Liberty, but while you will see better performance out of Enlist One when spray coverage is great, it’s not quite as important as it is with Liberty, since Enlist One moves better throughout the plant. Both Liberty and Enlist One are only labeled up to R1 (first flower).
As you know, your options for broadleaf control postemerge in conventional soybeans are terrible. This coming year, we are planning on raising a bunch of conventional soybeans on our farm. The 3 Pre’s and using a Group 15 plus a PPO early post are an absolute necessity. I realize we will have invested about $20 in getting five chemistries and four modes of action, but that’s nothing compared to the yield loss if we have even a few weeds left in the field. After our first two applications, we’ll probably use Cobra where necessary if we see any kochia or waterhemp, but we should easily exceed 99% weed control prior to that point.