July 24, 2025

Wildfire smoke affects Midwest crops

Agronomy manager explains impact

Smoke fills the sky over fields as wildfires on the West Coast and in Canada affect the Midwest.

WAUKEE, Iowa — With recent wildfires in the western United States and Canada, smoke has made its way to the Midwest.

It particularly may affect already vulnerable crops, according to an agronomist.

“The risk of yield loss and reduced stalk health (from wildfire smoke) is likely greater when smoke imposes an additional stress upon a crop that is already experiencing the effect other stresses, like disease or drought stress,” said Mark Jeschke, Pioneer agronomy manager.

The relationship between wildfire smoke and crop growth is complex, with both positive and negative effects on photosynthesis, according to Pioneer.

Three key factors play a role in how smoke influences photosynthesis: diminished light intensity, greater light diffusion and elevated ozone concentrations.

Reduced sunlight intensity. Much like a hazy cloud cover, smoke reflects a portion of incoming sunlight, reducing the amount of light available to plants. Because plants depend on sunlight to carry out photosynthesis, any reduction in light is potentially detrimental to crop productivity.

Increased sunlight diffusion. Wildfire smoke can significantly increase the diffuse fraction of photosynthetically active radiation, which can benefit plants by increasing light use efficiency and the availability of light to lower canopy leaves.

Increased ozone levels. Ground-level ozone is a damaging air pollutant that is harmful to human health and plant growth. Elevated ozone levels have the potential to significantly reduce crop yields. Dicot species, such as soybeans, are generally thought to be more susceptible to yield reduction than monocot species, such as corn — although research has shown that corn and soybeans are both susceptible to yield loss from ozone pollution.

Wildfires in western North America are expected to become more frequent and intense in the years ahead, making it an area of concern for many.

Erica Quinlan

Erica Quinlan

Field Editor