Variable = one good word to describe planting and growing conditions for the 2025 crop year. This is true across the country and applies within locations too as variable temperature and precipitation patterns have occurred this year. Realistically, that’s not that unusual but it seems like more places have gone from one extreme to the other since spring. The USDA recently released record yield projections (188.8 bushels per acre) and increased acres of corn planted to the highest acreage since 1937. Despite the record production projections, there are rumblings from the field about disease pressures in various areas which could limit the potential for a record harvest. Mycotoxins can occur even when yields are good. So, what mycotoxins could we expect in new crops knowing conditions have varied and there is disease out there? This article is the first in a series sharing insights into potential mycotoxin contamination patterns in the 2025 corn crop.

Many factors influence the development of fungal diseases in crops and such factors also play a role in those fungi producing mycotoxins. Weather-related factors such as temperature and humidity are especially key and drive regional differences in mycotoxin occurrence and contamination patterns because different climates support different types of molds. Other stressors, including foliar diseases, hail and wind damage, insect or wildlife damage, and weed pressure, increase susceptibility of the plant to a mycotoxin-associated fungal infection.

The fungi which cause foliar diseases such as Tar Spot, Gray Leaf Spot, Northern Corn Leaf Blight, Common Rust, Southern Rust, and Anthracnose have not been associated with production of mycotoxins, but such leaf diseases can reduce yields and increase the risk for secondary disease by molds that can produce mycotoxins. Mycotoxins are more than a grain issue - stalk rot and root rot can be caused by mycotoxin-producing molds so mycotoxins can be present throughout the corn plant. Scouting fields during the growing season can help identify disease pressure and guide timely and appropriate management tactics that can boost plant health and may reduce the risk for mycotoxin accumulation. It’s important to keep in mind that the use of fungicide, although beneficial to overall plant health and crop yields, does not necessarily eliminate the potential for mycotoxins.

Mycotoxins can continue to accumulate as crops stand in the field and the risk extends post-harvest while feedstuffs are in storage, through feeding out. Table 1 provides an overview of potential situations that can increase the risk for fungal disease and subsequent mycotoxin production. 

Remember that visual inspection alone is not a reliable indicator that mycotoxins are present in feed, so it’s necessary to screen your grain, silage, and other feedstuffs to understand what mycotoxins you may be dealing with.  If you would like to submit samples for analysis as part of our dsm-firmenich complimentary mycotoxin analytical service, please contact your dsm-firmenich account manager. And continue to follow The Digest as harvest progresses to receive updates from our 2025 mycotoxin survey!

Resources:

National Corn Growers Association. 08.12.2025. USDA Raises Record Projections for Corn Yield and Production