FOLEY, Minn. — With drier weather persisting across much of the tri-county area, concerns about corn and soybean emergence may be warranted. Since it has been a few years since we have dealt with potential stand issues, I decided that a short review of the information related to stand counts and potential replanting was in order. Much of this information can be found in greater detail at extension.umn.edu/crop-production under the Corn and Soybean tabs.
The first step is to determine the current population of what was planted. For both corn and soybean this is approximately the same. Choose a row length is 1/1000th of an acre per your planting row width and count the healthy plants in that section of row. This makes scaling your calculations up to one full acre easier. Also, finding the length of 1/1000th of an acre per your row width is as simple as looking at tables provided online. For narrow row or solid seeded soybeans, use a hoop that is either a 22.75 inch. or 32-inch diameter and use the table provided at the UMN Extension soybean page to help determine plant population. When taking these stand counts, randomly select multiple locations throughout the field. You will also need to take notes of uniformity of stand and seedling vigor which leads into the next step.
Investigate the problems associated with emergence. In the case of this season, dry weather is the primary concern. However, you will also want to check for potential issues with herbicides, fertilizer, disease, and insects. As with many early season emergence issues some may need correction this growing season and others may need to be considered for next season.
As for replanting decisions, it is time to combine the above information. First look at the population and uniformity of the existing stand. Keep in mind that uneven emergence does not necessarily mean a significant drop in yields and may not be profitable to replant. Potential yields for both corn and soybeans should be calculated. Tables containing potential yields based on planting populations and dates for both corn and soybeans are useful in this case and can be found at the Extension website. Next, factor in the costs of replanting including seed, labor, and fuel. Keep in mind that if the cost of replanting outweighs the added yield then replanting will likely not be economical. Finally, check the labels of any pesticides used to ensure that replanting can occur. While I hope that this information goes unused this season, it is always good to be prepared and have a plan B ready just in case.
If you have questions on the above information, please feel free to email me at firstname.lastname@example.org, or call at 608-515-4414. To receive future events, educational programming, and agronomic updates by email, signup at z.umn.edu/tricountysignup.
— Nathan Drewitz, University of Minnesota Extension
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