Answers are from the Indiana certified crop adviser panel: Betsy Bower, Keystone Cooperative, Lafayette, Ind.; Jeff Nagel, Keystone Cooperative, Lafayette, Ind.; Marty Park, Gutwein Seed Service, Rensselaer, Ind.; and Dan Quinn, Purdue Extension corn specialist.

 

I try to learn things from every season. What two things can I carry into future seasons?

 

Bower: Tar spot was found in Purdue plant pathologist Darcy Telenko’s research plots in northern Indiana on June 10 on V5 corn. This was the earliest detection on record and almost one month earlier than the previous earliest detection.

 

Next year may be a whole different ballgame. No two years are alike. Just because tar spot was tough one year, we may not see it until the end of July or later the following year. Pay attention to rainfall and conditions that support disease development in June. Pay attention to reports of finding tar spot in our local areas. Scout often.

 

Fundamental agronomics like optimal soil P and K and soil pH levels, as well as an intentional nutrition plan with N, S and micronutrients, help crops weather stressful conditions. Fields with good fundamental agronomics outyield those with poor fundamentals most of the time. Having optimal potassium improves water-use efficiency and nitrogen efficiency, and optimizes plant health and nutrient movement in corn.

 

Nagel: Be proactive managing tar spot. This year, some areas experienced significant pressure from tar spot for the first time. Some growers were reluctant to apply fungicide. Yield losses on some untreated fields were 20 to 40 bushels per acre. Fungicide timing is important because early applications can lead to a potential second application cost, while late applications do not significantly slow disease progress, leading to yield loss. We are still learning if two applications might provide a positive return on investment.

 

Don’t overlook corn leaf aphids. Apparently, some combination of nutritional and/or sugar content of certain hybrids were conducive to rapid reproduction, leading to unusually high populations. Entomologists suggested not spraying post-pollination, as natural predators/fungi would provide rapid natural control. This did happen in some cases, while other populations persisted. When combines rolled, it was apparent that yield was often negatively impacted.

 

Park: In northwest Indiana and east-central Illinois, we learned that corn leaf aphids can have a significant impact on yields. This year was different, as they arrived in early July, and populations exploded. They sought out corn just prior to the tassel stage, and we found that they liked some hybrids more than others. We don’t expect to see this again, but we need to be aware of them when we are scouting. 

 

We need to stay vigilant with fungicide applications. Tar spot infestations continue to be hard to predict, and there can be a very significant penalty for not applying a fungicide or applying it too late. Economics drove some growers to cut out the fungicide application, and they are paying the price for that decision. 

 

Quinn: It can be very difficult to predict when and where tar spot will appear and how severe it will become. Improper management can result in significant yield losses. Hybrid selection, scouting and informed fungicide applications will be very important.

 

Another important takeaway is that you need to set the crop up the best way possible from the beginning. Corn that emerges poorly; is stressed early and at critical periods; and does not have proper protections, nutrition or weed control will not reach its fullest potential.