Harvest is happening across many areas of the Corn Belt, and some farmers are noticing an unusual phenomenon in the field. Rather than the typical beige-colored dust being expended from the combine,
black dust has taken its place instead, heightening the concern of many farmers over the operational safety of their equipment.
The underlying cause of this issue can be attributed to an increased amount of microscopic fungal spores that have been produced this fall by
saprophytic fungi and proliferated on senesced corn leaves and stalks. Saprophytic fungi are incredibly common, and are not pathogenic to plants, animals or humans. They are a part of the natural process to break down crop residue and return nutrients back to the soil. They grow on dead organic matter, in contrast to parasitic fungi that feed on a living host.
Several factors contribute to the increased presence of saprophytic fungi in certain years. Fields that experience pre-mature death are most susceptible because the earlier plants die, the earlier these saprophytic fungi can establish in the field. Factors such as drought, in-season disease pressure and nutrient deficiency in fields may all induce pre-mature cell death and allow saprophytic fungi to grow. Late-season rain, humid weather and morning dews may be partly to blame for the heavy presence of saprophytic fungi this late in the season. Common smut (typically caused by systemically infected seeds/seedlings) may also be another contributor to the black dust.
Fortunately, a presence of saprophytic fungi on leaves and husks will not affect the quality of the corn grain nor hinder its yield. Proper functioning and safety of combines is also unlikely to be compromised from this occurrence. A dust mask or respirator may be considered for those with respiratory sensitivities or ailments and is recommended when cleaning harvest equipment.
For more information and insights on what may be contributing to darker dust behind your combine, contact your local
Golden Harvest Seed Advisor or agronomist.
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