Potassium (K) plays vital roles within corn plants for carbohydrate, nutrient, and water flow. It is instrumental in gas exchange from the plant to the atmosphere as it regulates the opening and closing of the stomata of the leaf; it is also a key component in cell walls which add to stalk strength. Potassium is essential for photosynthesis, maximizing water use efficiency, helping maintain plant health, increasing test weight of grain, and nitrogen use efficiency. A corn plant requires almost as much K as nitrogen (N); however, when looking at soil test values across the Midwest, soil test K values have been falling. This is largely due to increased grain yields removing higher amounts of K from the soil and insufficient K applications.

Ear and kernel development is a lengthy process for a corn plant. It begins at the V5 growth stage as the plant determines kernel rows around and then continues to V12 where the potential maximum length of the ear is determined. Next comes the pollination stages where the maximum number of kernels is established and then finally, R5 when the maximum kernel size is established.

Any stresses, natural or manmade, during this process, can lead to abnormal ear set. Many of the abnormal ears and their causes are detailed below. Accurate diagnosis of these abnormalities can help prevent future problems in the field.

Short husking is best described as “corn ears outgrowing their husks.” It results in more exposure of the ear tips to environmental conditions and increases the potential for reduced grain quality.

Corn rootworm (CRW) is a pest that, if left unmanaged, can cause economic damage in most of the Corn Belt. Damage can result from root-feeding while they are in larval form and from adult beetles clipping silks during pollination.

Crown rot infections are caused by both fusarium and pythium species. These fungi enter the plant via the root system during periods of prolonged saturation, predominately between the V2 and V7 growth stage. Because these fungi persist in higher moisture environments, infections are more prevalent in wetter soils, tighter clay soil textures, higher magnesium soils, and ponded areas of fields. While these infections occur early in corn development, they can persist much longer as the visual signs are not easily detected until later in the grain fill period.

Broad areas of the Corn Belt have experienced one of the most challenging planting season in recent memory. Farmers did what they do best, and bided their time for a planting window. Corn acres from South Dakota to Ohio were planted weeks later than what is typical. And while many farmers are already worn out from the extended planting season, most are more nervous about what’s to come.

The good news is that late planted acres still have great yield potential. If Mother Nature starts cooperating, this season has abundant hope of producing competitive yields.

There are many reasons a corn crop may fail. In some years it’s a late frost and in others, soil surface crusting. Regardless of the reason the stand fails, it is important to destroy the original crop before replanting. Yield losses can occur if just 5,000 of the original corn plants remain to compete with the new stand. Therefore, it is imperative to successfully eradicate as much of the existing stand as possible.

During rainy springs, fields may flood or even stay saturated for long periods of time. Flooded fields have two forms: saturated or waterlogged (where only the roots are flooded) or submerged (where the entire plant is under water). Saturated or waterlogged soils are more common than completely submerged plants, but they can both be damaging to yield.

Early-season frost damage is a stressful physiological event that can slow plant development. The net impact of early-season frost will depend on the health of the plant before the frost, the extent and duration of the freezing temperatures, and the growing environment following the frost.

There are numerous stalk rots that affect corn in mid to late season. Weather, nutrition and genetic disease tolerance all play major parts in the disease cycle. Plants move nutrients from the stalks to the ears during grain fill. High yields mean heavier ears. These two phenomena combined can make stalk quality issues a problem even in very high-yielding areas.