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Fungal diseases create dust challenges during harvest.

Agronomy Bulletin 110 ─ Black Molds Nuisance In Cornfields

Corn plants with prematurely dead or dying tissue are most susceptible to sooty molds.


Wet and/or humid conditions can lead to black, sooty molds in cornfields at harvest. Sooty molds are species of secondary saprophytic fungi — microorganisms that feed on dead plant material. The presence of these molds can create excessive amounts of black dust when harvesting affected cornfields.

Factors to Consider

  • Drought stress
  • Dust
  • Equipment maintenance
  • Harvest timing

Action Plan

  1. IDENTIFY THE ISSUE. Saprophytic fungi can grow on plant tissue that has died prematurely — often due to heat or drought stress — or is senescing. Various species of saprophytic fungi cause a black or sooty appearance, thus they are often referred to as sooty molds. These molds can rapidly colonize dead plant tissues after rain events, especially those followed by warm humid weather and morning dews. Local pathology labs can confirm fungal species present in fields.
  2. EVALUATE RISK. Sooty molds are not known to produce any toxins that are harmful to livestock or humans, and grain harvested from these fields should be relatively clean. However, stalk lodging could become a significant concern if harvest is significantly delayed and growers should monitor field conditions and evaluate the risk of harvest losses due to lodged corn.
  3. DEAL WITH THE DUST. Wear a dust mask during field scouting or harvest, especially if allergies or respiratory problems are a concern. Due to large amounts of dust produced by the molds, check and clean equipment and replace filters more frequently.


Although they are a nuisance, sooty molds caused by saprophytic fungi on corn plant surfaces are not a major agronomic or health issue. The most significant problem is dealing with the extra dust these fungi produce. For more information, contact your local Mycogen Seeds customer agronomist or trusted agronomic adviser.

Published on Tuesday, August 26, 2014