Insights from Ag Plus Answer Plot Day

Our Answer Plot Day brought growers together with experts from WinField United to dig into this year’s growing season, evaluate hybrids side by side, and talk through strategies to maximize yield potential. If you weren’t able to make it, here are some of the biggest takeaways.

The weather has played a major role in this year’s crop. In Minneota, we’ve seen 18 inches of precipitation in the last 90 days and 24 inches since April 1. To put that in perspective, our 30-year average is 20–22 inches for an entire year—so we’re already above that by late August.

Soil moisture has been high as well, with saturation levels running around 35–40% compared to an ideal range of 30–35%. That kind of environment creates both opportunities and risks: plenty of water to drive growth, but also a higher risk for nutrient leaching, disease pressure, and delayed fieldwork.

Growing Degree Units (GDUs) are an important measure of crop development, and this year has been slightly behind average. As of late August, Minneota sits at about 2,200 GDUs since planting. For reference:

     • Mid-90-day hybrids typically need around 2,400 GDUs.

     • 100-day hybrids require closer to 2,700 GDUs.

With August days adding 20–25 GDUs, we’re behind, but not enough to cause major concern at this stage. Learn more about GDUs.

• Kernel set happens early. By the time corn is knee high, the plant has already determined its maximum number of kernels around. Management from that point forward is about protecting and filling those kernels.

• Grain fill is a long window. From tassel (around July 20) to physiological maturity is roughly 60 days. Right now, we’re about five weeks into that window.

• Early dent = halfway. When corn enters early dent, the crop is only halfway through grain fill. Many growers overlook this stage, but nutrition and protection still matter here.

Think of your corn plant’s leaves as solar panels—the more leaf surface you keep green and healthy, the more sunlight is converted into sugars that build grain. Protecting those leaves is directly tied to protecting yield.

Fungicide timing at tassel remains one of the most important yield protection steps. Applications at this stage cover the first 4–5 weeks of grain fill, keeping upper leaves clean during the time when they’re capturing the most sunlight.

Not all hybrids respond the same way to fungicide. Seed guides outline which hybrids show strong yield responses and which are less responsive—using that data helps ensure you’re getting the best return on investment.

Adjuvants also make a big difference. The ear leaf and the three leaves above it contribute about 70% of yield. Products like MasterLock® help ensure spray coverage and deposition, so fungicides stick where they need to.

Nitrogen management was another major theme of the day.

     • Deficiency signs: A yellow “V” shape on leaves indicates nitrogen stress. The plant will sacrifice lower leaves to move nitrogen into the ear. If deficiency reaches the ear leaf, yield losses become significant.

     • Critical uptake window: Corn takes up about 75% of its nitrogen between knee-high and tassel (roughly June 1–July 15). Stabilizers can protect your investment during this window by slowing conversion to nitrate and reducing leaching.

     • Nutrient interactions: Nitrogen doesn’t work alone. Potassium helps pull nitrate into the plant, but sulfur is needed to strip oxygen so the plant can actually use it. Micronutrients like zinc, manganese, and boron are needed only in small amounts, but they play a big role in making macronutrients more effective.

Foliar micros at V5 and tassel can support yield, especially in years with heavy rain and leaching.

One of the most valuable parts of Answer Plot events is seeing hybrids perform side by side in the same conditions. At our Minneota plot, we have eight rows of each hybrid on display, making it easy to compare ear size, kernel counts, and plant health.

We checked a couple of 100-day hybrids during the walk-through: one was carrying 14 kernels around, while another had 16. That difference may not seem like much, but multiply it across an entire field and it adds up to bushels. Having these visual comparisons helps take the guesswork out of seed decisions for 2025.

Tar Spot: This polycyclic disease is one to watch. Every speckle on a leaf is its own infection site, meaning the pathogen can complete multiple life cycles within a single growing season, producing new spores and causing secondary infections as long as environmental conditions are favorable. This ability to spread and reinfect the host plant repeatedly contributes to the challenge of managing tar spot, as the disease can progress rapidly and cause significant yield losses. Coverage and deposition are critical to managing it effectively.

Waterhemp: Control has been extremely tough this year. Once waterhemp hits 8 inches, it has a dozen growing points, making it almost impossible to kill with post-emerge programs alone. Pre-emerge herbicides with multiple modes of action are essential, and adjuvants, water conditioners, and surfactants all improve effectiveness. Planning ahead for 2025 weed control should start now.

ABOUT

Corporate Office
1100 East Main Street
Marshall, MN 56258

(507) 532-9686

subscribe for Ag Plus updates

© Copyright Ag Plus Cooperative | Privacy Policy