A topic of conversation that I frequently have this time of year is whether or not foliar micronutrients should be added to the sprayer tank as we begin post emergent spraying. If fields have been well managed for N,P,K and the other macronutrients then it would be a good idea to consider micros as they might be limiting your yield potential. Most of the corn around the countryside is at the fourth leaf stage or older which is an important time in its development. The number of kernel rows is starting to be determined and soon the corn plant will start to rapidly elongate and have a high demand for plant food nutrients which include needed micronutrients like zinc, manganese, and boron. If you would like to know more about adding micronutrients, tissue and soil testing can be done to determine nutrient levels in the plant and how much your soil can supply.
Another reason to apply foliar micronutrients is to offset the micros being immobilized by glyphosate (Roundup). Glyphosate is a chelator so it binds to positive ions in the plant like zinc and manganese. You may notice yellow flash in plant tissues after they have been sprayed with glyphosate because this product has temporarily made some micronutrients unavailable to the plant. These symptoms will eventually go away after enough days have passed, but they can be lessened or prevented by adding foliar micronutrients with the glyphosate. With more micronutrients available, stress will be reduced and the plant can continue optimum growth. From company research and what we’ve seen ourselves, we consistently achieve at least a 2 to 1 return on investment with the foliar micronutrients that we recommend. If you have any questions about foliar micronutrients or about tissue and soil sampling, contact your agronomist at WS Ag to get more information.