Farmers in Iowa as well as other states across the U.S. experienced a rough start this growing season. Saturated soils and cool, sometimes freezing, temperatures in the spring plagued corn-growing states from Nebraska to Indiana. Scouting your fields now, during critical growth stages, can provide useful insights for the remainder of the growing season. The following observations and recommendations are provided by Mycogen Seeds agronomists.

Root development issues plague some fields
Planting and growing-season challenges can create a number of root development issues for corn. Examine these three areas to determine if corn roots are compromised.

• Root architecture. Wet soils prohibit roots from extending into the soil, which can lead to standability and lodging issues later in the season. Sidewall compaction from planting in wet soils, when followed by warm, windy days, also can lead to root architecture challenges. Farmers should dig up roots to look for pancaking or flat roots.

• Root health. Split some stalks open to examine the crown. The early onset of crown root rot is due to excessive cool and wet soil conditions during early development. Early-season diseases such as pythium and rhizoctonia can impact root-to-crown health. Damaged crowns typically lead to more overall plant stress and can create stalk rot issues later in the season.

SPLIT STALK: Cut off a section of the stalk about 2 feet up, with the roots attached, and split the stalk section lengthwise with a knife.

• Root scarring and tunneling. In most areas, corn rootworm egg hatch occurred early in June. Farmers should dig up several roots now. Larvae should be big enough to be seen on roots. Feeding damage also may be apparent as brown, pruned roots. Damaged roots hinder the plant’s ability to take up water and nutrients, which can lead to poor grain fill and lodged plants. It can also leave the plant vulnerable to additional disease pathogens.

Uneven emergence and replant situations
Weather challenged corn seedlings this year, leading to uneven emergence and replant situations in some fields this spring. Late-emerging plants compete for sun and nutrients with neighboring early-emerged plants. According to Iowa State University Extension, depending upon the difference in days between early- and late-emerging plants, yield loss can range from 7% to 23%.

Farmers should scout fields and note the number of smaller or shorter plants in a stand. ISU Extension provides additional help in determining potential corn yield loss. Understanding yield potential can help farmers make in-season management decisions.

LOOK INSIDE: Examine the tissue inside the stalk. The tissue should be white, indicating a healthy stalk.

Watch for signs of disease in cornfields
Environmental conditions influence which corn diseases may be present during the growing season. And the severity of the diseases is influenced by several factors. Those include early-, mid- and late-season weather; the crop’s disease levels in the South; and winds out of the right direction at just the right time are just a few. Here’s how to combat them:

• Disease management. Early-season stress can make corn plants more susceptible to disease and reduce the plant’s ability to combat stress. As farmers walk fields nearing pollination and during pollination, they should look for key diseases like gray leaf spot and northern corn leaf blight, and consider whether applying a foliar fungicide is economical for the field’s yield potential. In low-yield potential fields, an application may not be worth the investment.

• Prioritize your fields. As farmers scout, they should also prioritize fields by hybrids. Some corn hybrids are more susceptible to foliar diseases than others. If you have fields with hybrids that are known to be susceptible, scout those fields first. And be ready to harvest those fields first in the fall.

This is a critical point in the growing season for scouting, the agronomists point out. And it is an optimum time to get out in your fields to look for issues that could potentially put a damper on harvest. Harvest first those fields where lodging or stalk quality is a concern. Farmers should work with their local agronomists for scouting and management input, or visit mycogen.com/agronomy for agronomic management tips.