Uneven emergence common in southwest Michigan corn fields
Will the unevenness of stand emergence cause yield losses in your corn fields?
Planting progress is way behind normal in many areas of the Midwest and Michigan. However, parts of southwest Michigan have been blessed with enough dry weather to allow for corn and soybean planting. Corn emergence on the sandier soils has looked very good. We have, however, seen some challenges in seedling emergence on soils that were just a little wetter, had slightly more clods or were heavier in texture.
Initial scouting showed pretty significant skips in many fields that were planted between May 5 and May 12. Evaluation of these areas on May 18 revealed that seed placement was generally good and the seeds had germinated, but not yet emerged. Crusting did not appear to have been a significant issue. By the morning of May 23, most of these seedlings were at spike. Why did we see so much variation in germination compared to past years? It appears that slight variations in soil moisture and temperature at the time of planting may have caused most of the challenges. Soil temperatures really dropped following the heavy rain on May 13 with probe readings falling from the 70s on May 12 to temperatures in the low to mid-40s on May 16 at the MSU Enviro-weather Station at Lawton in Van Buren County.
The more important question is, “Will the unevenness of stand cause yield losses?” Looking at data published in NCR 344, a stand exhibiting 25 percent uneven emergence (within the row) that emerged within 1.5 weeks caused between 6 and 9 percent yield loss. Most of the fields that I have walked through that show uneven emergence have between 10 to 15 percent of the stand affected (at worst) and the plants are about 7 to 10 days behind in emergence.
While it remains to be seen what the final plant populations will be, it appears that overall stands will be fairly close to the intended populations. I did find some evidence of black cutworm clipping in a few fields I walked. Also, sandhill crane activity is starting to pick up in fields. If you have skips in your fields, I would encourage you to evaluate the seedlings to make sure that the seed or seedlings are there and appear as though they will emerge. If you have to re-plant portions of the field, it is better to make that decision earlier rather than later.