As we approach and pass the V6-V8 growth stages throughout much of the corn growing region of North Dakota, let’s do a quick recap of where we are and where we are going. At this point, much of the ‘action’ around growing a corn crop has passed. We have prepared the land, fertilized, planted, and sprayed herbicide either as a pre-post combo, or all post. Weed control should be done or nearing completion as very few herbicides are labeled past V8 stage and height, as the corn crop canopies. We are entering the part of the growing season where we are monitoring the crop, while hoping for warm days and nights that are coupled with adequate soil moisture and timely rains. Given that much (unless we get corn rootworms or various diseases), if not all of the management of a non-irrigated corn crop is over in North Dakota, let’s refresh where we are at with the growth of our corn crop, physiologically speaking.
The corn growing point comes above the soil surface around V5. V5 is also when you begin losing the lower collared leaves, V1-4, to withering and compression of the leaf nodes. Therefore, those interested in keeping track of growth stages need to remember that past V5, the first leaf collar you see is likely the 5th or 6th leaf collar. This could be checked by digging up a plant and slicing it down the middle, however in our area there are almost no growth stage dependent applications at the later V stages to the reproductive stages, so it is only a curiosity. At the V6 growth stage all plant structures including the tassel have developed at the growing point and the stem is rapidly elongating in height. We are not quite at V10-12, when the second yield component (after plants per acre) of the number of rows of kernels is complete. However, we should all be hoping to keep the soil moisture high so that the plant is highly productive as we approach these critical growth stages where the next yield component is determined.
We are making great progress with our heat units this year as indicated in the table. We are well ahead of the 30 year average as indicated by a random sampling of NDAWN stations (https://ndawn.ndsu.nodak.edu/) in North Dakota. I used the corn planting date for hybrid trials that I planted, which were all finished by about May 1st, for the math. Everyone’s individual GDD will be a bit variable depending on planting date, but this shows the trends.
Overall, keep a watchful eye on your corn for nutrient deficiencies at these growth stages as well, which will hurt our yield if they show up. In conclusion, based on what I have seen in the field, we are heading for yet another year with our corn crop well past “knee high by the fourth of July,” and that is a GREAT thing.