As the old sports cliche goes, “It’s not over till it’s over.” So, until the growing season ends, agronomists across the Midwest recommend scouting and making decisions based upon what you find.

Here are scenarios that may play out in 2024, depending on where you farm. All share a common theme: Scout and grow crops until the combine runs.

Tar spot in corn. In Indiana, tar spot is documented in 41 of 92 counties. Darcy Telenko, Purdue Extension plant pathologist, is fielding questions about whether applying a second fungicide treatment is worthwhile. Based on comments in the Purdue Pest & Crop Newsletter, Aug. 15 edition, here is the first question she asks in response: What growth stage is the corn?

“If at dent, R5 stage, or beyond, I would not recommend an application,” Telenko says.

Telenko also advises considering history of tar spot in your field, amount of disease you see currently and location in the canopy. If it’s been more than three weeks since the first fungicide application, the effective period for many fungicides has run out.

“If you make a fungicide application at this point, leave check strips to determine if the fungicide gave you a return on your investment,” Telenko says.

Southern corn rust. This disease is confirmed in a huge block of counties in eastern Nebraska and elsewhere. Here is what Tamra Jackson-Ziems, University of Nebraska Extension plant pathologist, says about possible second fungicide applications for southern corn rust in the Aug. 15 edition of Nebraska Cropwatch.

“Given the anticipated protection window of most products is three to four weeks, if a second fungicide treatment is needed, it should be made three to four weeks following the first one,” Jackson-Ziems says. “Second applications are much less likely to provide an economic return except in the cases of severe disease pressure.”

Soybean aphids. Here is advice on how to manage this pest as the season winds down. Robert Koch, Extension entomologist at the University of Minnesota, and multiple Extension educators drafted these comments, appearing in the Aug. 13 edition of Minnesota Crop News.

“Continue scouting for aphids on a regular basis through early R6, or full seed,” they write. “Through R5, use the threshold of 250 aphids per plant for determining when to apply insecticides. Soybean aphid can cause yield losses into early R6.

“However, a treatment threshold for early R6 has not been developed. Infestations of soybean aphid in early R6 may require an insecticide application if aphid populations are very large. Regular scouting and timely application of insecticides based on the threshold through the R5 growth stage should eliminate difficult decisions related to treatment of large infestations and preharvest intervals in R6.”

How long to irrigate. “As we look towards the end of the irrigation season, producers have an opportunity to improve their water productivity by properly timing their final irrigation application,” says Lucas Haag, northwest area crops and soils specialist in Extension at Kansas State University, writing in the Aug. 15 edition of K-State Agronomy eUpdates.

“This is an important decision, as an early termination of irrigation can result in reduced yield, primarily through reductions in kernel weight. Conversely, a late termination of irrigation results in unnecessary pumping and energy consumption, increases risk of soil compaction at harvest due to increased soil water content, and increases risk of water loss from the soil profile through drainage over winter.”

Haag recommends a four-step process to time the final irrigation application correctly:

Haag notes that most of the information he bases his comments upon was collected by the late Freddie Lamm at the Northwest Research-Extension Center at Colby, Kan.