Delayed Corn Planting in the Southern U.S.

• Recommended planting dates for corn in the Southern U.S. can range from late-February to April depending on location.
• Corn yield potential generally declines when weather conditions cause planting to be delayed beyond April; however, relatively good yields are still achievable through the first half of May in many areas.
  • In an 8-year University of Arkansas study, corn yield was maximized with April planting, but yield potential remained above 90% through the first half of May (Table 1).
  • In a 3-year Mississippi State University study, 90% yield potential was achievable with irrigated corn planted through May 5, and 84% through May 15 (Table 2).
  • Yield potential in both studies declined below 80% when planting was delayed until late May.
• Irrigated corn is generally able to sustain yield potential with delayed planting longer than dryland corn. Irrigation can also help mitigate the added risk of yield loss from heat stress during pollination and grain fill that comes with later planting.

• Planting corn later than normal does pose some challenges and additional management may be required to prevent or minimize yield-limiting factors such as heat stress, insect pressure, and disease pressure.

Foliar Diseases

• Late-planted corn is generally at greater risk for yield loss from foliar diseases because the corn is not as far along in its development when foliar diseases begin to infect the crop.
• Southern rust is of particular concern because of its ability to rapidly infest a field under favorable conditions. Re-infection can occur in as little as seven days, so fields may be damaged very quickly (Figure 1).
• Choose hybrids with solid disease resistance. Scout and apply foliar fungicides as needed. Economic yield responses to foliar fungicides are generally more likely with late-planted corn.

Corn Earworm

• Late-planted corn can be at greater risk for damage from corn earworm.
• Light traps or pheromone traps can indicate when adults are flying. Scouting can be done in the field by looking for eggs on the green silks and turning back the silks at the tip of the ear to look for larvae.
• Pioneer^® brand corn with Optimum^® Leptra^® insect protection provides strong above-ground insect control with a superior level of efficacy against ear-feeding pests for cleaner ears and improved grain quality.

Heat Stress and Irrigation Timing

• If available, irrigate in a timely fashion especially during pollination. This will help ensure that the corn plant cools adequately during periods of intense heat that later-planted corn has to endure.
• Higher temperatures during pollination and grain fill increase the vapor pressure deficit, which increases the amount of water needed by the crop to sustain photosynthesis.
• Corn planted after April may require 1 or 2 more furrow irrigations or 2 or 3 more pivot irrigations compared to corn planted in March or April (Kelley, 2021).