Ken Ferrie is hearing from farmers across the Midwest who are trying to decide whether to make a second fungicide application to hybrids affected by heavy disease pressure. In southern Indiana, he is seeing many fields of corn at R5 that are fighting tar spot, which is particularly concerning because of how quickly the disease can take down a corn crop.
“There, many fields have been sprayed twice, and farmers are entertaining a third application,” says Ferrie, Farm Journal Field Agronomist, based in Heyworth, Ill.
At this point in the season, Ferrie recommends corn growers scout fields with tar spot to identify where it is located on the plants. Look to see if the disease is moving around and can be found higher in the plants, and not just along the base of the stalks.
“With corn prices expected to lead with a three in the front, it does make it hard for growers to decide what to do next,” Ferrie acknowledges. “We have corn stretched out here in Illinois from R3.5 to R5, and at R5 we still have 30 days to go in this growing season.”
Another consideration farmers need to think through is how long they will need tar spot infected corn to stand in the field before harvesting it.
“Many of you guys have indicated you’re going to let corn dry in the field, and you don’t care if that takes until December,” he says. “In corn with tar spot in the midway up in the plants at R4 and with the plan to dry corn in the field, you may need to help that crop out with a second fungicide pass.”
Don’t Over-Estimate Yield Counts
2024 will go down as the year of the aphid for many growers. Some hybrids are giving up 15 to 35 bushels per acre to the pest, which is adding insult to injury by contributing to green snap.
“In some fields, aphids have caused the plants to abort one-third to all of the ear. Green snap below the ear means a complete loss, and green snap above the ears is resulting in about a third of an ear, which is probably going to go through the stripper plates,” Ferrie says.
As you do yield checks in these fields, he says to start with all the non-affected corn ears and calculate the yield on them first. Then, make a yield estimate on the poor ears, divide this number by 90, and then add that number to your unaffected ear yield estimate to arrive at your final yield estimate.
“These aphid-affected plants often have uniform stalk diameters, which can be missed when you’re checking your ear counts out there,” Ferrie cautions. “Growers who disregard poor ears and calculate the yield on good ears and use uniform plants as their ear count are going to over-estimate yields.”
Ferrie notes that the impact of aphids is worse on some hybrids than on others, but to not simply resort to pulling those hybrids out of your lineup for 2025, because many of them are high-yielding.
“We just need to be aware if aphids are an issue in certain hybrids as we plan for next season,” he says. “For now, those affected hybrids need to be watched for harvest loss this fall. Don’t let them get through the stripper plate, and get as much corn off aborted tips as possible,” he adds.
Listen here for this week’s complete Boots In The Field podcast: https://www.croptechinc.com/bifr-8-19-2024/
