By Brian Hefty
If you could gain 85 bushels of soybeans by investing $85 per acre more than what you currently are, would you do it?
When I asked you that question, you likely thought one of two things:
- There is no possible way anyone can gain 85 bushels per acre in soybeans
- Brian has lost it, because I’m never spending $85 per acre on anything
In 2017, we had about 20 acres out of 1000 that yielded zero because of white mold on our farm. Sure, 20 acres isn’t much, but it is frustrating when you are going along at 85 on the yield monitor, only to see zero pop up one minute later.
One of our big topics at the Ag PhD Agronomy Workshops this past winter was white mold. Whether you had some spots at zero or just some areas of 10 to 20 bushel yield loss (we had both), you are no doubt wondering what to do about this disease so the issue doesn’t happen again. Over the next few months, we will likely talk to you about Contans, manganese, selecting more tolerant seed varieties, and crop rotation. Mid-season, you can’t do any of those things, other than maybe a little foliar manganese, but you can do the things I list below.
- Look back at your soybean yield maps from 2016. If you plant soybeans every other year in each field, you last had beans there in 2016. Look at all the spots of yield loss. If you believe those were from white mold, now you can make a variable rate fungicide application map.
- Cobra is a decent weed-killer, but it may be even better at reducing white mold. Thanks to a price reduction this year, you can run with a half rate (that should be enough for white mold suppression) at about $8 per acre.
- Endura is the best fungicide on white mold. Yes, it costs $35 per acre, which is why you want to use it sparingly. On our farm, I intend to spray it in spots where white mold hit us in 2016. That’s about 10% of our acres. Instead of spending $35 per acre on every acre, when you only spray 10% that amounts to just $3.50 on all the soybean acres. Yes, the sprayer will have to run over quite a few acres, turning on and off where needed, but the savings are huge. Granted, EVERY ACRE could get hit hard by white mold this year, but on our farm, we’ve never had that before. It has always been in isolated spots when it shows up.
- Spray your first fungicide application at R1, first flower. White mold starts with mushrooms in your fields. The mushrooms shoot spores at your plants, and the fungus enters most commonly through spots where flowers have dried up. An R1 to R2 timing has typically given the best results on white mold.
- Do a follow up treatment 2 weeks after your first spray. As a general statement, an R2 to R3 (first pod) application of fungicide has given the best yield results, due to plant health benefits and overall disease protection. While I will spot spray my Endura, I fully intend to broadcast spray my next treatment. Priaxor, Trivapro, and Stratego YLD are fantastic products for this timing. You could also run with your own combination of something like Domark plus Topsin plus Quadris, since both Domark and Topsin have activity on white mold, and Quadris is one of the best plant health products available.
By the way, I mentioned investing $85 per acre for a white mold treatment program. Here’s how I would spend that $85 if white mold was a very severe issue for me. Again, there is no way I’m doing this on every acre, but if I can identify the very worst spots and only treat there, it should be pay big dividends in a bad white mold year.
- $19 – Contans in fall or early spring (make sure the product is kept FROZEN until the day you spray it)
- $8 – Manganese in fall or early spring (if DTPA test is less than 20 ppm)
- $8 – Cobra (1-2 weeks before flowering)
- $35 – Endura
- $15 – R2-R3 follow-up fungicide
White mold is a terrible problem in many different crops. Endura and Proline are the top two fungicides labeled for white mold suppression. Both are expensive, and neither is the total answer, but if you have white mold, you will absolutely want to consider spraying early and often.