By Brian Hefty
Soybeans are very different from corn. When it gets late in the season, corn yield is mostly already determined. Corn takes up a lot of nutrients and moisture earlier in the year. With soybeans, the opposite is true. When corn reaches its maximum height and root size at tasseling, think about how small your soybeans are and how much more growth they have yet to achieve.
Because of these vast differences, late-season applications in corn don’t typically make as much difference in yield as late-season applications in soybeans do. Think about both 2012 and 2013. We found many farmers throwing in the towel with their soybean crops because they looked bad early on or because they had almost no rain. The farmers who continued to protect and care for their beans came out far ahead because, again, soybeans develop late.
We have tried a lot of things in our soybeans, and we’ve had hundreds of farmers working with us on these things as well over the last few years. Here are the late-season treatments we have found to pay pretty consistently at R2 (full flower) to R3 (first pod).
- Insecticide. If you find even a relatively low level of harmful insects, spraying should pay a great ROI. If you are going for high yields, since the soybean price is high and since insecticide only costs $2 an acre, you only need a few bugs to justify treatment. On our farm, we’ll spray when 10 aphids per plant are present at R2 to R3. Also consider that other harmful insects (grasshoppers, bean leaf beetles, etc.) may be present, which further lowers your threshold. If you have spider mites or are worried about getting them, switch to Cobalt, Lorsban, or Brigade (generic Capture). If you only have aphids but want to NOT kill the lady beetles, use Transform for around $6.
- Fungicide. I am shocked at how many people now use fungicide in corn but don’t spray fungicide in soybeans. Our trials across the upper Midwest have shown fungicide pays more consistently in soybeans and is a little more hit and miss in corn. In fact, we have yet to see fungicide not pay on our farm in almost 10 years of trials. Fungicides can provide both disease control and other plant health benefits. We recommend combination (2 mode of action) fungicides (Priaxor, Fortix, etc.) for better disease control and resistance management, unless you are primarily after white mold. Endura, Proline, and Domark would then be better choices. Fungicides are more likely to pay when you have insects present, when you are going for higher yields, when you have wetter conditions, and when you have disease issues typically in your area. By spraying BEFORE you see a major disease outbreak, you will get much higher yields than if you wait to spray until you see lots of disease in your crop. Also, we have used half rates with great success in dry years. In a wet year (like this one for us) we use full rates, but we have had as high as a 17 bushel gain with a half rate of fungicide! If you are concerned about resistance building up, I wouldn’t worry too much. With the indeterminate soybeans we have in the Midwest, they are usually only halfsize at R2 to R3, so a half rate isn’t out of line. And really, how many acres are treated with fungicide anyway? Don’t get me wrong. A full rate is great, but if the weather is dry a half rate typically gives a better ROI, so you decide for yourself what you want to do.
- Foliar Fertilizer. This is the one that for us we had a tough time finding the right product and the right timing. We have tried a lot of things over the years with no success. What has worked each of the last 3 years has been AC-97 at just 1 quart per acre. Foliar fertilizer is more likely to pay when you are shooting for high yields, have adequate moisture, when temperatures are 85 or below, and when the crop needs fertility the most (like at first pod, R3).
On our farm, when we mix all 3 of these things together the investment is about $25 per acre. That may sound like a lot, but the breakeven is just 2 to 2.5 bushels per acre, and we usually gain 5 to 7. The key is to check the yield closely. For example, if you “only” gain 3 or 4 bushels, that means you still made an additional $10 to $20 net per acre depending on the soybean price, but will 3 or 4 bushels extra show up on your yield monitor? Probably not. Either use a weigh wagon or reset your yield monitor each round where you are running strip comparisons so you get exact weights for each trial. We experiment with a lot of things on our farm, and that’s what led us to this insecticide/fungicide/fertilizer treatment that we now do on every acre.