What Mycotoxins Should We Expect Following an Interesting Growing Season? (Part 2)

Figure 1. Overview of major factors that influence mycotoxin contamination.

The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) website provides maps which track temperature and precipitation across the US.³ Although many parts of the Corn Belt experienced a period of dry, warmer than typical weather immediately following planting, many areas picked up timely precipitation into July and August, reaching near average or above average rainfall during those months and more moderate temperatures in some places during silking. A pocket of heat brought record temperatures across the Plains, Midwest, and South later in August and extended into September, leading to widespread warmer and drier weather again. During this time, drought conditions expanded or intensified in areas such as the Northern Tier, Upper Midwest, Southern Plains, and Southeast.¹ As we head into October, forecasts show many areas of the Corn Belt will continue to be drier and warmer than typical through the middle of the month which should allow harvest to begin and continue in many areas without much delay. However, more seasonable temperatures and potentially wetter weather are expected as fall progresses.

Figure 3. NOAA National Centers for Environmental Information Divisional Average Temperature Ranks May-July 2023 (Period 1895-2023), August 4, 2023.3 Many of the top corn producing states have experienced at least above average temperatures during much of the 2023 growing season while parts of the eastern Corn Belt were near or below average.

Figure 4. NOAA National Centers for Environmental Information Divisional Precipitation Ranks May-July 2023 (Period 1895-2023), August 4, 2023.3 Many of the top corn producing states have experienced below average to much below average precipitation throughout much of the 2023 growing season.

Figure 6. Significant hail events which occurred May through September, 2019-2023. Nine of the 13 states represented on the map have had a greater number of significant hail events this year vs. last year, with states like Indiana, Kansas, Missouri, and Nebraska seeing the greatest jump in number of events.

An additional factor to consider is insect pressure as these pests can create stress for plants and enhance entry of mycotoxin-producing molds through damage or lesions. Additionally, insects can act as vectors which spread mold spores. The InsectForecast5 website is a great resource to use to monitor pest pressures in your area.

Foliar diseases also play a role in crop health, but diseases such as Tar Spot, Gray Leaf Spot, Southern Rust, and Northern Corn Leaf Blight, although of fungal origin, are not directly associated with the production of mycotoxins. Although not a primary risk for mycotoxins, such foliar diseases stress the plant and open the door for secondary disease by molds that can produce mycotoxins. Risk for such foliar diseases is variable across the Corn Belt this year, but Bayer Crop Science has Corn Disease Risk Maps on their website6 and can help provide some insight to disease pressures in your area. Scouting fields to determine disease pressure can guide timely and appropriate management tactics that can boost plant health, which may help limit risk of mycotoxins, even if management strategies (i.e., fungicide application) do not directly address mycotoxin-producing fungi. Supporting plant health and stalk integrity is beneficial, especially as crops stand in the field later into the harvest season as weather conditions may deteriorate and compromise the plant prior to harvest.

Believing that we can accurately predict what mycotoxin contamination patterns will look like in all bushels of corn that will be harvested this fall is absurd. Too many factors influence disease occurrence and contamination patterns, and those factors vary tremendously across the US and over time, resulting in an excessive number of potential combinations and outcomes. However, we’re willing to shake the magic 8 ball and see what insights we can harness from all the information that was presented in this article. In general, we believe that the “outlook is not so good” and there is a high likelihood for mycotoxins to be present in potentially challenging levels in the 2023 crop based on conditions which occurred over the course of the growing season. However, with harvest just under way in many top corn producing states, we suggest that you “ask again later” as our annual mycotoxin survey accrues data to better characterize what mycotoxin occurrence and contamination patterns truly look like in the 2023 corn crop.

Figure 7 outlines a few of our general predictions. DISCLAIMER: the following predictions are based on available information at the time of writing this article. We cannot guarantee contamination will follow these predictions, but check back in future issues of The Digest to see what contamination patterns look like according to the annual dsm-firmenich mycotoxin survey as harvest progresses and feeding of 2023 corn ingredients commences.

Figure 7. General mycotoxin predictions for 2023 US corn crop.

Keep in mind that single stressors increase the risk of mycotoxin contamination, but combinations of stressors, even when occurring individually at low to moderate levels, can enhance risk for mycotoxins that much more. It’s difficult to calculate and assess an aggregate stress level that incorporates all the factors that have been reviewed in this article. Despite this, understanding what stressors occurred in your area can help provide guidance as to what mycotoxin(s) to be on the lookout for and how frequently new crop feeds should be screened following harvest.

If you would like to submit samples for mycotoxin analysis to better understand risk in your feeds, contribute samples to the annual mycotoxin survey, or are curious to learn more about the analytical services dsm-firmenich offers, please contact your dsm-firmenich account manager.