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Guide to corn replant decisions

Farmers across Missouri face crop do-over decisions after the recent rain deluge.

Mindy Ward, Editor, Missouri Ruralist

May 22, 2024

2 Min Read
Corn plants beginning to sprout through soil
WET TIMES: While some corn plants are out of the ground, some seed just went into the ground. Recent heavy rains and localized flooding have farmers across the state looking at replant options. Mindy Ward

It’s decision time for Missouri farmers as rain-soaked fields threaten crop survival.

Meteorologists continue to call for more precipitation this week, which leaves farmers in a holding pattern, whether planting for the first time or replanting.

For those with corn in the ground and at various growth stages, there is a small window to determine replant options. Once the rain stops and water recedes from cornfields, plant growth will resume within three to five days. This is when to begin evaluating stand and plant survivability.

Here’s a summary of five steps from University of Missouri Extension and Iowa State University Extension to help with the replant decision:

1. Verify remaining plant population. Assess the affected part of the field by counting plants in several “random” areas. Avoid focusing only on the worst areas; characterize the entire field. Count plants in at least three places, ideally in one-hundreth of an acre. Consider whether damaged plants will survive and contribute to final yield.

2. Assess plant stand uniformity. Uneven emergence (row to row) may not benefit from replanting. If the delay in emergence is less than two weeks, replanting may yield only a small increase. If more than half of the plants emerge three weeks later, replanting could increase yield by about 10%.

Related:Replant soybean acres, or stay with your race plan

3. Calculate expected yield from existing stand. Use the tables below from MU Extension to estimate yield based on original planting date and actual population. High-yield environments are those that consistently yield more than 190 bushels per acre on average. For example, if the original planting date in high-yield environments was May 1, a population of 36,000 plants per acre yields maximum potential. Even with a population of 24,000 plants per acre, yield potential is still 82% of maximum.

Moderate-yield environments — yield as percent expected, represents average upland and nonirrigated fields

High-yield environments — yield as percent expected, represents high-yield upland and bottoms, and irrigated fields

4. Estimate replant yield. Planting date and target plant population are used to estimate the yield potential of the replanted field. For example, replanting high-yield environments on June 5 at 36,000 seeds per acre results in approximately 75% of maximum yield. Compare this to the original crop planting date and its existing population. Consider costs and the lack of guarantee for a good stand with replanting.

5. Determine replanting costs. Consider tillage, seed, fuel, pesticides, labor, and potential fall frost risk. Check with your seed dealer for hybrid seed availability and any rebates for replant situations.

Remember that these are general guidelines, and specific field conditions may vary. Consulting a local agronomist or Extension agent can help you make the best decision.

Other resources for replant decisions:

MU Corn and soybean replant questions

MU Replant Decision Aid

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About the Author(s)

Mindy Ward

Editor, Missouri Ruralist

Mindy resides on a small farm just outside of Holstein, Mo, about 80 miles southwest of St. Louis.

After graduating from the University of Missouri-Columbia with a bachelor’s degree in agricultural journalism, she worked briefly at a public relations firm in Kansas City. Her husband’s career led the couple north to Minnesota.

There, she reported on large-scale production of corn, soybeans, sugar beets, and dairy, as well as, biofuels for The Land. After 10 years, the couple returned to Missouri and she began covering agriculture in the Show-Me State.

“In all my 15 years of writing about agriculture, I have found some of the most progressive thinkers are farmers,” she says. “They are constantly searching for ways to do more with less, improve their land and leave their legacy to the next generation.”

Mindy and her husband, Stacy, together with their daughters, Elisa and Cassidy, operate Showtime Farms in southern Warren County. The family spends a great deal of time caring for and showing Dorset, Oxford and crossbred sheep.

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