Assessing stands, weeds and nutrients

By Roy A. Ulrich, Technical Agronomist for Dekalb/Asgrow for Southern Ohio

Planting corn and soybeans in the spring of 2021 in the state of Ohio was once again wracked with the inevitable decisions of when to plant and when not to plant. Countless hours were spent staring into those crystal balls of smart phone weather apps that we all seem to praise or curse depending on the outcome or the forecast. This planting season has been stretched out over a two-month time span, with a wide variety of planting and growing conditions that accompanied this spring’s weather pattern. This has left us with fields that have a wide variety of strengths and weaknesses in the crop we have established in the field. While this may not be the ideal situation, this crop is far from being a success or failure and is a long way from being in the bins. So, we need to take stock of what we have and don’t have within our fields and how can we maximize the crop we have established and minimize the environmental stresses it faces later this growing season.

             The three keystone pieces to assess at this point in the growing season are: stand establishment, weed control and nutrient availability. At this point in the growing season, we are passed the point of deciding whether the stand we have is adequate or not, but it is a good opportunity to go back and reevaluate the relative strength and evenness of that crop. The slow accumulation of GDUs during planting led to some fields not having as even of an emergence as we would like to see, however, with the calendar date looming and less than ideal forecasts in the future, some of those stands were kept. As corn enters this rapid growth phase, it is easy to determine the percentage of the stand that is significantly behind by several growth stages and will not provide the same yield potential as the earlier emerging plants. While fields with slightly uneven emergence doesn’t predetermine that field for below trend line yield, it does give an indication of the overall potential productivity within the operation. 

            Successful weed control is paramount for optimizing yields. The erratic spring weather has almost certainly resulted in tweaks for herbicide plans on most farms, either because of delays in application from wet weather or because the weed’s size and spectrum has changed due to weather delays. Scouting now to ensure those herbicide applications are still providing clean fields gives some time to adjust and make another application to corn if growth stages still allow for herbicide applications. This will also provide an opportunity to tweak post- herbicide applications. Scouting for weed size and species will allow for implementation of herbicides that provide the greatest efficacy, especially with the soybean technology of today offering multiple herbicide tolerances. 

              Nutrient availability is the final piece to consider for this stage of the growing season, based on which fields are primed for success. Fields that received large rainfall events and were saturated earlier in the season may have lost some nitrogen. If a large portion of a corn crop’s nitrogen has been subject to loss there are tools available now to apply nitrogen later in the season and more opportunity to make up for those losses. There are also nitrogen models that can help estimate the amount of nitrogen losses based on product, application timing, and rainfall events. 

            Time spent scouting now and reflecting on the weather from the spring will help set the stage to determine which fields are key candidates for fungicide and insecticide treatments that will most certainly be a hot topic in the coming months.