By Brian Hefty
- The maximum in-crop total use rate for Roundup PowerMAX per season is 64 oz. If you used 32 oz. twice already, you’re done. Now, I doubt that spraying more than 64 oz. of Roundup total will hurt the crop much, but it is off-label, illegal, and you will undoubtedly get a fine from your state’s Department of Agriculture if you get caught. All glyphosate products have similar per season maximums, so don’t think that switching glyphosates will help you.
- Volunteer corn must be controlled. Even a small amount of volunteer corn can hurt yield, as well as host insects and diseases that can then damage next year’s crops. It only costs around $2 an acre to kill volunteer corn, so make sure you stop it. You can tankmix any volunteer corn herbicide with almost any other herbicide, fungicide, or insecticide, so it’s easy to add in.
- Fungicide use in soybeans has skyrocketed in the last 5 years because yield results have been good. However, don’t go in expecting to gain 10 extra bushels or anything like that. Over the last 5 years, we have typically tripled our money when using fungicides in soybeans, and that’s what I’d shoot for if I was you. The best timing is R2 (full flower) to R3 (first pod) if you are only spraying one time. If you are after white mold, spray twice, about 2 weeks apart, starting immediately. Also, spraying Cobra will help reduce white mold issues, but spray that separate from fungicide.
- Foliar fertilizer has been hit and miss in soybeans. My first choice is to fertilize in the fall or at planting, as you should get more consistent results. However, last year we used AC-97 for the first time and gained about 7 bushels per acre. We sprayed at about R2. We will be running many more tests on that product this year.
- Don’t believe the high insect threshold numbers that were developed 10 or 20 years ago. Bug thresholds vary based on economics. In other words, when the soybean price is good, yield potential is high and insecticide is dirt cheap, you don’t need many insects in your fields to justify spraying. Plus, while you are out there applying a herbicide or fungicide, you can throw an insecticide in without adding any leaf burn to your crop. Keep in mind that for spider mites, only products containing Capture and Lorsban give much control, and Lorsban is one of the few insecticides that may add leaf burn when tankmixing with other pesticides.
- Don’t believe the high water rates some people will tell you to use when spraying herbicides. Certainly, all herbicides work better if you improve coverage. However, when crops and weeds are small, you don’t want much water. With any glyphosate product, never exceed 10 gallons of water per acre. When you get higher than 10 gallons, the droplet concentration is lessened, and I promise your control will be reduced. If you use low water volumes, make sure you keep spray pressure up. Low water and high pressure means smaller spray droplets and increased drift potential, but it also means good spray coverage and weed control. As always, spray with caution.
- Pre-harvest intervals (PHI) are usually not a big concern, but keep them in mind if you are spraying unusually late. Many insecticides have a 30 day PHI, but many herbicides are 60 days. CLICK HERE to see a list of PHI’s for commonly used soybean pesticides.
- The use of plant growth hormones has been exploding in all crops as the science continues to improve around hormone use. We have been applying MegaGro with glyphosate for the last few years, as we see reduced yellowing in the soybeans and higher yield when it is used. It’s interesting because as Darren and I have visited some of the top farms around the world, we often find them using plant growth hormones in whatever crops they are raising, too. I suggest you at least begin experimenting with MegaGro or other plant growth hormone products, as it is an inexpensive way to gain yield and improve plant quality.
- If Roundup is no longer working, you may need to hand weed. Products like Harass, Flexstar, Cadet, and FirstRate are once again commonly used on soybean farms across the world because Roundup isn’t killing every broadleaf weed anymore. However, these products will only control weeds up to 4 inches tall in most cases. You can burn back big weeds with the use of conventional herbicides, but if you want to stop those weeds from going to seed, you may have to hand weed your fields. I know you probably won’t do this, but if Roundup-resistant weeds are allowed to go to seed, expect to invest an extra $20 to $30 an acre each year for the next several years to control all those weeds.
- Keep scouting. If you want a great crop, you’ve got to keep checking your fields. Most of the yield in soybeans is determined in late July and August. If you have ample fertility and you can get some timely rains, you may have the best crop you’ve ever raised. We had great conditions early for soybeans when it was hot, sunny, and dry. Soybeans love that, at least early in their life cycle. On our farm in 2006, we went 3 months getting only trace amounts of rain before we got 2 big rains in late July and August. The result? 60 bushel average soybeans. What I’m saying is just because it may have been dry on your farm early, don’t give up on soybeans. Conditions so far have been perfect for beans in many areas.