By Andy Westhoven, AgriGold regional agronomist
At this point in the calendar, undoubtedly, there are many corn fields planted around the area. Just as undoubtedly, planting conditions will be like the story of Goldilocks and the Three Bears — some will be too cold and wet, some too hot and dry, and some just right. The role as an agronomist usually travels down the road of the first two situations in Goldilocks’ tale — less than ideal planting conditions. Somewhere in the eastern Corn Belt, after a corn field has been planted, a torrential rainfall will occur and/or there will be a cold period where a grower might wonder, “What is to become of the corn seed I just planted? How long can it last in the soil before rotting and dying?”
Last season almost gave growers a false impression of corn emergence when most fields emerged in about 8 days. This is certainly not the norm. Most growers would average close to 12 to 14 days for corn to emerge year in and year out. It is a general understanding that corn seed treatments can last 3 weeks give or take. This is also the answer to the title question: How long can corn seed hold its breath? The answer is 3 weeks. The best way to improve upon a more rapid and uniform emergence is to plant into a warming trend.
Easier said than done, right? From the time of planting the seed until emergence, the best defense a corn seed has is the seed treatment, as it does not have any natural defenses. Typical corn seed treatments consist of fungicide and insecticide protection. The fungicides usually play the larger part during the “hold my breath” moment.
With temperatures in the mid to low 60s, field saturation, and cloudy weather are the perfect environment for slow to little corn seed growth and development. When a corn seed is not developing, pathogens — namely Pythium and Fusarium — could potentially attack a vulnerable seed. Once an infection occurs, it still could take up to several weeks to know the consequences. If the corn seed germinates and emerges, the disease could still ultimately kill the plant before it can “outgrow” the pathogen. In this case, the best advice is for warmer and drier weather for a period where the balance of power can be swayed back into the corn seed’s favor for rapid growth. Rapid growth is really the best medicine for a disease-infected corn seed or seedling.
In addition to the disease threats, many insects prey on vulnerable seeds. During a prolonged emergence period, insects such as white grubs, wireworms, and seed corn maggot are the most common culprits to feed on corn seeds. While most seed treatments provide excellent protection in this arena, it is not uncommon to find hotspots in a field based on a variety of different reasons.
Ironically enough when you consider a seed holding its breath, oxygen in the soil is another factor one must consider about seed viability/longevity in the soil. Any practice that reduces oxygen or pore space in the soil profile can also cause seed germination/emergence issues. Obviously, a wet, saturated field would qualify here. Outside of weather conditions, though, compaction can be a large threat.
Compaction could be caused from heavy equipment. But, if one dives deeper, there is often planter compaction caused from too much down pressure. This is the pressure that is placed by the actual row unit being either too heavy and/or having too much pressure applied. Most of these can be reduced by planter settings, but still can be a hidden problem.
In that ideal world, most would simply hit repeat of the 2018 spring season. Unfortunately, there is no easy button here and each year, farm, and field present unique challenges that keep all operators on their toes. Let’s hope that everyone finds that warming trend!