The combination of late planting, abundant fall rain, and early snow can delay corn (Zea mays) and soybean (Glycine max) harvesting (Figure 1). Additionally, blanketing snow can reduce or prevent the soil from freezing to depths that can hold up harvesting equipment. With these conditions, harvest could be delayed until spring.
The amount of potential yield loss for corn can be dependent on plant populations, stalk lodging, ear drop, ear size, grain quality, wildlife damage, and additional rain or snowfall amounts.
A Wisconsin study (Table 1) shows the average percent loss in corn yield for the years 2000 and 2001 when corn was left in the field throughout the winter and harvested monthly through April.1 Lodging in 2000 increased the percentage of lost yield compared to 2001.1
Corn kernels can become subject to sprouting during early-spring time melting before field conditions allow for harvest. Very little yield loss information is available for soybean fields left through the winter; however, the potential for yield loss is likely to increase. Heavy snow can cause soybean plants to lodge or break off and become difficult to harvest.
During melting cycles, pods can become wet and break open when seeds enlarge because of increased moisture content. Exposed seeds can drop to the ground, lose quality, or become food for foraging wildlife. High plant populations and soybean products with marginal standability characteristics may have a negative impact on winter-time standability. Additionally, as harvest is delayed, the opportunity for Diaporthe (pod and stem blight) increases.
The cost of drying harvestable wet corn in late-fall or early-winter should be compared to the breakeven cost of leaving corn in the field through winter. If the drying bill is less than the estimated yield loss from lodging, ear drop, disease, and wildlife, then fall harvesting if at possible should be accomplished.
Table 2 provides a total drying charge compared to a 5% to 40% winter yield loss at grain prices ranging from $3.00 to $4.25 per bushel.1 A higher corn price justifies increased drying costs while lower prices can decrease justification and increase the opportunity to leave corn in the field and harvest as weather and conditions permit throughout the winter.
Factors to weigh prior to harvesting a delayed harvest field:
1Schneider, N. and Lauer, J. 2009. Weigh risk of leaving corn stand through winter. University of Wisconsin. http://corn.agronomy.wisc.edu/
2Staton, M. 2017. Recommendations for a late soybean harvest. Michigan State University. http://www.canr.msu.edu/
Additional source: Jasa, P. 2010. Combine recommendations for spring harvest. CropWatch. University of Nebraska. https://cropwatch.unl.edu
Web sources verified 10/17/18.