Production Blog: Grain Issues 10/08 12:41

   Grain Quality Concerns Rise for Corn, Soybeans

   Prolonged wet weather in parts of the Corn Belt is leading to issues with 
mold, fungus and disease as harvest ramps up.

Jason Jenkins
DTN Senior Crops Editor

   JEFFERSON CITY, Mo. (DTN) -- After seemingly unending rain fell across 
portions of the Corn Belt during September, the month of October began with a 
week of mostly dry weather, allowing farmers to start nosing combines into 
fields. What they're discovering is that the late-season moisture has led to 
some quality issues with the crop.

   Excessive rainfall, especially in portions of Iowa, has favored mold and 
fungal development and seed diseases, causing issues for both corn and soybeans.

   "Of the 58 weather stations we have in Iowa, nearly three-quarters of them 
reported at least 4 inches of rain in September," said Gretchen Mosher, who 
manages the Grain Testing Laboratory in the department of Agricultural and 
Biosystems Engineering at Iowa State University. "In some cases, stations 
recorded 400% to 600% of their normal rainfall. While the majority of Iowa 
isn't experiencing any drought, the timing and the magnitude of the rain has 
produced from grain quality implications for both corn and soybeans. I wouldn't 
say it's everybody, but it's pretty widespread."

   Much of the Iowa crop remains in the field. According to the latest USDA 
Crop Progress report released Monday, Oct. 5, only 7% of corn and 5% of 
soybeans had been harvested in the Hawkeye State, both well below their 
five-year averages of 20% and 38%, respectively.

   In corn, Mosher said the key concern is the growth of fungus and field mold, 
especially ear rot. Ear rot decreases yield and reduces the food, feed and 
grain quality of harvested grain. Some fungi that produce ear rot may also 
produce mycotoxins, which are hazardous to animals and humans. 
Mycotoxin-contaminated grain must be segregated. Much of this corn will have 
higher-than-normal moisture content.

   "It's not going to handle well," she said. "Fungus likes wet and warm, so we 
need to get that corn cool and dry as it's coming out of the field. We don't 
want it sitting around in a grain cart or semi for longer than it needs to."

   Soybeans present a less straightforward situation as the crop in many cases 
was still filling pods when the rains began. Issues from pod swelling and 
splitting as well as seed splitting and sprouting could occur, which makes 
beans more susceptible to fungus and mold.

   "It is really a balancing act," Mosher told DTN. "Because of the oil in the 
soybeans, you don't want to heat them too fast, but you want to get them dry 
and cool quickly."

   One issue that farmers may encounter is purple seed stain, which is caused 
by a fungus, Cercospora kitkuchii. Soybeans will show a light to dark purple 
discoloration and can have reduced germination.

   "Now, stained beans aren't illegal to blend, but you have to have some good 
stuff to blend it with," Mosher said. "I don't know if that's going to happen, 
at least based on what I am hearing and what I'm seeing in the state of Iowa."

   While purple seed stain doesn't reduce yield, it can lower the value of the 
crop through dockage, as can other issues such as splits and weather- and 
disease-damaged kernels.

   Since 2023, soybeans of other colors (SBOC) haven't been an official 
grade-determining factor; however, if SBOC is greater than 10%, the soybeans 
would be classified as mixed soybeans, rather than yellow soybeans, based on 
U.S. Standards for Soybeans.

   Farmers don't have control over the weather, but Mosher noted that they do 
have control over harvest, post-harvest and storage management. She recommended 
focusing on infected fields and prioritizing harvest as soon as field 
conditions allow.

   "It's not going to get any better in storage, so getting it out of the field 
and dried down as soon as possible can help prevent further growth of mold and 
fungus and limit losses," she added.

   Longer-term storage with lesser quality grain can also present challenges, 
and maintaining grain condition will be paramount, both for the value of the 
crop and grain bin safety.

   "We've got a lot of stuff that's going to be out of condition, so all the 
pieces are in place for bad things to happen within the grain bin," Mosher 
said. "Over the winter, we need to be checking these bins more frequently to 
avoid issues like bridged grain."

   Read more from Mosher on grain quality concerns here: 
https://crops.extension.iastate.edu/post/grain-quality-concerns-recent-wet-weath
er.

   Read more from DTN about soybean grading changes here: 
https://www.dtnpf.com/agriculture/web/ag/crops/article/2023/07/14/usda-removes-s
oybeans-colors.

   Jason Jenkins can be reached at jason.jenkins@dtn.com

   Follow him on social platform X @JasonJenkinsDTN




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