Part Five: Pre-Harvest Issues to Watch out for in a Late Planting Year (Like This One)

As we look ahead to harvest, it’s time to start mapping out your pre-harvest plan. You’re likely already looking at the forecast to predict when early frost dates might creep up, checking your harvest equipment for maintenance needs and scouting crops for any late-season issues. These steps are always important to ensuring a smooth harvest, but scouting before harvest is going to be a necessity this year. With the abnormal start to the planting season, late-season diseases and stalk issues may impact harvest. Here are a few things to look for.   

• Stalk rots and prioritizing harvest by field and hybrid
• Stalk rots can be a significant issue every year in the southern Corn Belt.  However, in wet years, the problem can lie hidden until late in the season. Corn that would normally burn up because of drought and heat will continue to appear green and growing, but inside the stalks, fungi could be feeding on structural tissues and lignin. Late-season wind storms can then cause corn to stalk lodge.  Examining hybrids for their stalk integrity late in the season is an important step to determining the order that harvest should commence. A good practice is to apply pressure about the ear node or leaf and see if the hybrid snaps at some lower node. If the hybrid does snap, split open other stalks to determine the level of incidence and severity to make decisions regarding harvest priority. 
• Tip-back due to photosynthate loss in grain fill (excess water, disease, drought, etc.)
• Why does the tip of my corn ear not fill to the end? This question is a very complex one that has multiple correct answers. Silk integrity, viable pollen availability and insects are three possibilities. However, another issue that is showing up this year is due to a lack of photosynthate (food made from the process of photosynthesis) availability to fill the last kernels on the cob. This can be caused by cloudy conditions, diseased tissue not being able to produce photosynthates, drought conditions that limit a plant’s ability to take up available nutrients. However, I believe the most common problem this year is nitrogen loss from fields with early applied nitrogen and wet conditions leading to nitrogen leaching through the season. Nitrogen is mobile in the soil and moves with soil water, so with wet conditions, much of our nitrogen was carried with soil moisture deeper into the soil profile where it cannot be readily accessed. This leads to stalk cannibalization in prolific hybrids and severe tip-back in non-prolific hybrids. Where tip-back is observed, stalk quality should be evaluated as in previous points to determine standability for harvest.
• Green beans in soybeans due to late planting
• The majority of the soybean genetic material that is sold in southern geographies is indeterminate in plant growth habit. This means that the plants will proceed vegetatively growing while initiating reproductive phases. This can mean that pods will develop late into the growing season and will not have the opportunity to reach physiological maturity prior to harvest. This can result in green beans at harvest. This situation is especially prone to happen in years when planting gets pushed to later dates due to adverse planting conditions. In areas where this may be the case, early desiccation of soybeans can be an option; however, the timing is always the key to not limit yield. Look to pods for proper timing — 80 to 90% of the pods should be turning color from green to yellow or brown prior to an application of a desiccant such as Gramoxone XL, Aim2EC or Sharpen. These products can also be mixed with insecticides to control boll worms (pod worms in soybeans) and help with limiting the number of green beans at harvest. Fields that received a strobilurin fungicide application should be considered a priority as they have a tendency to stay greener, longer.

In all these situations, your local Stine agronomist and sales representative can assist you in making pre-harvest decisions.