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Soybean Emergence and PPO Injury

There are a few different things that I feel we are seeing right now in these fields, the first is some obvious emergence issues from the rainfall we have had and the winds sealing the ground up tight. As these winds have been very difficult for spraying this season, we love to see them for drying purposes so we can head back to planting, but on the other side of it the downfall is that the ground seems to be running together forming a crust, that still has wet cool soils underneath, therefore causing soybeans to struggle to push through. The best case scenario I feel is that hopefully we will see some rain to reduce some stress on the plants, and the other option that I know many have turned to is rotary hoeing to help break that crust up and speed up the drying process and let some air flow down to the roots of the plant. I know rotary hoeing beans when the hypocotyl is right at the soil can be concerning, but if this is the option that you chose I encourage you to run through the field some and evaluate the results you are receiving as you start. This allows us to make a good judgment call on whether you feel you are doing more damage than you are good.

The second issue and maybe bigger concern that I am seeing right now is some PPO injury (Flexstar, Flexstar GT and Prefix) are a few common names) on emerging soybeans. As calls have been coming in the common theme that I know we have all been seeing is the hypocotyl (neck of soybean) having a brown spot on it (almost like taking a cigarette and burning the back of the stem), or for those beans that have emerged we may be seeing some swollen yellow to brown cotyledons, or the first trifoliates showing some puckering.

Attached is an article that I received this morning that goes into some greater detail and shows some pictures of this particular issue. I feel Jackie does a great job explaining this in detail and illustrating what to be scouting for so please see the attachment for more details, as I will try not to double up on what she is saying. However with the symptoms I mentioned that have been seen there a few takeaways I want to highlight.

We need to look at the crops we put in the ground like us as human beings. As we all experienced last week no one enjoys going from beautiful 80 degree temps in t-shirts, to cool rainy periods, where we have to put winter jackets back on and be concerned about potential frosts. Just as we don’t enjoy that, corn and soybean plants don’t either, and unfortunately they don’t have the option to cover up and protect themselves from the elements. Last week was a tough week for soybean growth and development and when cool rainy conditions move in, the potential for herbicide injury increases. The reason much of the chemistry we use today contains a soil residual based PPO element, is because this is some of the most effective chemistry we have seen on controlling glyphosate resistant waterhemp and palmer amaranth, and 9 times out of 10 the plants can metabolize this chemistry and move on with no issues being noticed.

This year is one particular year that everything lined up for potential injury and it did in some cases. What I want to make sure we all realize is that there is nothing anyone did wrong, the weather was great when the soybeans were going into the ground, soil conditions were nice to plant in, and the chemistry we used and have used in the past is very effective for controlling the weed species we are going after. These days unfortunately to stay ahead of what the southern United States has faced with resistant weed species we need to be continuing to put down the best foundation chemistry that we can, at the appropriate rates to control these weeds. As I mentioned in a previous article I wrote for the United Prairie website (, the easiest weed to kill is the one that never emerges. So as we continue to move forward in this planting season and future planting seasons let’s not lose sight of what our ultimate goal was going into this, with controlling those troublesome weeds we all struggled with last year.

At this point though what should you do? Monitor these fields as we get through the next few days here, and assess periodically to make sure that replant isn’t needed. We have finally gotten some sunshine and heat so these are going to make the plants much stronger as we try to push through this. If rotary hoeing is necessary evaluate your results at the start of hoeing to insure we are doing more good than bad going across the field. Finally PLEASE feel free to give your United Prairie representative a call to evaluate with you. As I mentioned in the beginning I have been getting a number of calls on these. Thank you for taking the time to read through this, have a good evening, and a safe remaining planting season.

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