By Darren Hefty
How’d you like more free time and fewer worries as your wheat crop grows? How’d you like a little more cash to spend after harvest? Would it be fun to see your crop looking better than other fields around you all year long? Using a residual herbicide along with your wheat burndown could do all those things for you. Here are a couple products that could fit for your operation and the tips to make them work their best.
The two main residual herbicides to use ahead of wheat are Sharpen and Pre-Pare. Since both are fairly new to the market, there are a few things to explain with each.
Where Broadleaf Weeds are the Main Concern:
Use Sharpen
Sharpen is an incredible burndown herbicide with underrated residual activity, especially as you increase the rate. Sharpen is basically just straight Kixor, which you’ve no doubt heard advertised over the last couple of years. Kixor is just a brand name for all the products that contain the active ingredient saflufenacil.
Sharpen is a PPO inhibitor in the same family as Valor and Authority. It must be used prior to crop emergence, as it will severely burn emerged crop. Sharpen is broadleaf specific in that it only controls annual broadleaf weeds. The advantage of Sharpen compared to other burndown herbicides is the speed of burndown. It’s not just fast, it’s very fast. Prior to wheat emergence, you can use Sharpen at up to 2 ounces per acre. Adjuvants help in the speed and effectiveness of the burndown. Use MSO (methylated seed oil) at 1 gallon per 100 gallons and AMS (ammonium sulfate) at 17 lbs. per 100 gallons.
Where Grasses are the Main Concern:
Use Pre-Pare
We get a lot of questions about using Pre-Pare each year ahead of spring and winter wheat, because having great weed control early in wheat really boosts yield. Our conservative recommendation has been to use 0.2 ounces per acre even though the maximum labeled rate is 0.3 ounces. Here’s why.
Pre-Pare is degraded or broken down by soil microbes. Environmental conditions can decrease microbial activity. These conditions include prolonged drought and/or cold temperatures; soils with low organic matter levels (below 2.0%); and high pH soils above 7.5. Our other concern is any potential overlapping applications in your fields. This is most likely to occur where there are terraces, point rows, etc. If that happens, a 0.2 ounce application quickly becomes a 0.4 ounce application in a small area of the field, potentially causing a crop response situation.
With Pre-Pare, we get more concerned in spring wheat applications than winter wheat. We also are more concerned about using too high a rate when the soil organic matter levels are below 2.5% and pH levels are above 7.0. Arysta also changes their rate recommendations when you get outside of these levels. The biggest challenge is that soil pH (and the level of organic matter, for that matter) can and does vary greatly within a field. I personally own ground that has had soil pH variance from 5.1 to 8.4 within the field. To be on the safe side, we typically recommend using no more than 0.2 ounces per acre unless we know the fields it will be applied on very well. Also, why take a chance of injury in parts of your field when you know you’re going to need to come back post-emerge and clean up the escapes anyway? This is a very similar approach corn and soybean farmers take in Roundup Ready and LibertyLink crops. Use a reduced rate of a pre-emerge herbicide down and clean up the escapes in-crop.
Resistance management is another key reason to include an ALS herbicide like Pre-Pare in your cropping plan. By using Pre-Pare, you can eliminate most of your annual grass problems as well as some of the broadleaf weeds you have. If your fields are beginning to see ACCase-resistant wild oats or green foxtail, using an ALS herbicide either pre- or post-emerge will have significant and immediate benefits for your farm. While pre-emerge herbicides are very good, they rarely kill 100% of all the weeds that could potentially come up all season. For that reason, a two-pass herbicide program offers your best weed control and maximizes your potential yield and profitability. If you use an ALS herbicide like Pre-Pare as your pre-emerge treatment, we’d strongly suggest using a different mode of action post-emerge (follow up with Axial, Discover, or Puma rather than Everest 2.0, for example).
Whether you choose Sharpen or Pre-Pare for your burndown and/or residual herbicide for wheat this year, using at least one will give your weed control program a boost and make farming a whole lot more fun.