Three years ago in Nebraska, we got many reports of waterhemp in corn that HPPDs (Callisto, Laudis, Impact, Armezon, bicyclopyrone, etc.) were not killing. That resistance has slowly been moving north, to the point that this year in southern South Dakota, we saw some epic HPPD failures. Yes, some sort of dicamba should probably be used post-emerge in corn to stop HPPD-resistant waterhemp, but how long will it be until we have dicamba resistance if that’s all you do? Pre-plant, we encourage you to consider a full rate of a Group 15 (Zidua, Harness, Outlook, Dual, etc.) along with another broadleaf killer like Sharpen.

If Roundup, HPPDs, and ALS herbicides won’t stop waterhemp (or Palmer pigweed)…

The full rate of Status is 7.5 ounces per acre, which right now costs about $25. That’s why many farmers use a reduced rate of 5 ounces or even less. The main weed killer in Status is diflufenzopyr. Since that active ingredient is from a chemical family not used in other crops, it’s great for resistant weeds. To make the Status work faster, it’s got a small level of dicamba in there, and it has a safener for corn. If you don’t like the price tag on Status, we suggest straight dicamba.

However…

We’ve all seen goosenecking and just plain old lodging in corn. You spray dicamba, and quite often the next day the crop is tipped over. Sure, it usually stands back up, but how much yield damage has been done? A year ago, we sprayed Clarity at V2 and still shortened the corn by about a foot mid-season, along with about a 13-bushel yield hit versus the untreated right next to it. This year, we compared Clarity vs. DiFlexx (think Clarity plus a safener for the corn) vs. Clarity plus MegaGro (beneficial plant growth hormones). Sprayed at V2 (that’s maybe 3-inch-tall corn), the DiFlexx outyielded the Clarity by 6.07 bushels per acre. The Clarity plus MegaGro outyielded the Clarity alone by 7.87 bushels per acre. The Clarity alone was just over 237 bushels per acre, which most people would say is great. My question for you is simply, “Are you giving up yield by not using a safened dicamba or MegaGro?” By the way, we also compared Clarity vs. DiFlexx at V8 (for some reason in our trial we didn’t do a Clarity plus MegaGro at V8, but next year we will test that, as well), with the DiFlexx giving a 14.1-bushel gain.

Whether dicamba gets approved or not for use pre or post in XtendFlex beans, I personally believe dicamba will be on more acres of corn than we’ve seen in a long time. There will be a lot of dicamba use, meaning high potential for dicamba drift and volatility.

The good news is unless dicamba shortens your susceptible soybeans, the odds of yield loss are very low, especially if your beans get hit pre-flower. Still, no one likes to look at leaf cupping, so the best defense is XtendFlex. We are making the switch on our farm. By the way, we only have one more year (hopefully) before Vyconic Soybeans come out. Those beans have tolerance to dicamba, Liberty, HPPD, Roundup, and 2,4-D. Until then, your best bet for keeping your leaves from cupping is to plant XtendFlex.

ON TOP OF THAT, FOLLOW THE LABEL AND DO EVERYTHING POSSIBLE TO AVOID OFF-TARGET MOVEMENT. While controlling physical drift is pretty simple (don’t spray when the wind is blowing toward a sensitive crop), stopping volatility is almost impossible. Every formulation of dicamba we have ever seen is subject to volatility.

In simple terms, the spray lands on a plant but then forms a vapor within 48 to possibly 72 hours that rises above the crop, often moving up to one mile downwind at that point. The biggest challenge with this is if the wind was out of the south when you sprayed, but it switches and comes from the north a day or two later, a tiny amount of dicamba may hit a sensitive crop nearby. While this almost never hurts yield, it certainly creates a lot of tough conversations. While I realize this will be challenging for you, if you have a sensitive field you are really trying not to hit, you will need the wind to blow away from that field for 72 straight hours after spraying. If that happens, you should be home free. I know. That’s a lot to ask, but if you only have one field of yours in a tough area, maybe you can time it out just right OR not use dicamba on that field. Liberty is great and the price per acre should be cheaper than dicamba. The 3 Pre’s (Metribuzin plus a Yellow plus Valor or Authority) will likely wipe out 95% to 99% of your small-seeded broadleaves before the year ever starts, and since this program usually costs less than two shots of Liberty or dicamba, it’s a great investment.