Herbicide applications are well underway on many corn acres. As the corn is starting to grow and beans are coming up, the spray season will become hectic. It is important to thoroughly clean spray tanks between applications, especially when alternating applications between different crops. Remember that even small amounts of certain herbicides can severely injure or kill susceptible crops. Even if a small amount of herbicide is left in the tank, some adjuvants can scour the sides removing remaining residues. Be sure to clean strainers, screens, endcaps and nozzle bodies, especially if the sprayer remained loaded overnight. These herbicide residues can contaminate the current or following loads. A few extra minutes taking precautions today may save trouble, time, and money tomorrow.

Corn is in the V3 to V4 growth stage.  This is a critical stage for corn because the plants are transitioning from relying on the primary (seed) roots to the secondary (nodal) roots. If this transition is delayed or interrupted, a field that emerged uniformly may begin to appear uneven in both growth rate and color. Pale green plants that are stunted may be in strips down a row with the rest of the row looking much greener and being taller. Fields planted in less than ideal conditions will be most prone to look this way. 

Potato leafhoppers will soon become active in alfalfa fields. Diligent scouting is the only way to detect leafhoppers before forage yield and quality has been reduced. Once “hopper-burn” is observed the damage has been done. There is mounting evidence that leafhopper damage not only affects the current cutting, but has negative residual affects to sequential cuttings as well as into the next growing season. 

Fertilize your alfalfa to maintain maximum productivity. The conversion of alfalfa fields to corn this spring emphasizes the need to harvest the maximum tons of the highest quality forage possible. It is extremely important to maintain the soil fertility of your hay fields. One ton of hay removes 50 lbs./acre K2O and 15 lbs./acre P2O5. 5 tons/acre of hay requires 250 lbs./acre K2O and 75 lbs./acre P2O5 and many growers report harvesting annual yields greater than 5 tons/acre. Sulfur is a nutrient that should not be ignored when fertilizing alfalfa. 20 – 25 lbs./acre S per year should be applied to alfalfa. Consider dividing your alfalfa fertilizer into two applications with ½ applied after the first cutting and the balance applied after the third cutting.

Originally published in the Iowa Spokesman. John Grandin serves the FS System as GROWMARK’s senior field sales agronomist. He can be reached at[email protected].