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May 22, 2003

Waterlogged fields have Hoosier farmers making replant decisions

WEST LAFAYETTE, Ind. – Heavy May rains have left standing water and soggy fields that have Hoosier farmers wondering about the development of their corn crop.

Low-lying fields and poorly drained areas are ponded or flooded from the excessive rain that fell on the state during the month. Bob Nielsen, Purdue University Extension corn specialist, said these areas are likely to see extensive corn death, and farmers must make decisions about whether or not to replant.

The corn crop's growth stage influences how excess water will affect the plants' health. Nielsen said corn plants younger than V6, or the growth stage in which six leaf collars are visible, are the most vulnerable to damage. Corn plants can only survive two to four days in standing water if temperatures remain cool. However, temperatures above 75 degrees may kill plants in 24 hours, he said.

"At this stage, the growing point is at or below the soil surface and is directly subject to the stress of oxygen depletion," Nielsen said. "These plants also are in the process of trying to establish a vigorous root system, and oxygen depletion can cause a significant amount of stress on these plants."

If farmers have flooded fields around creek and river bottoms, the decision to replant such a large area is fairly obvious. They face a more difficult decision, however, if only small patches of plants scattered throughout the field have been affected, Nielsen said.

Nielsen said farmers should examine the costs to replant versus the crop's yield potential and determine if there is economic return in replanting. Replanting patchy areas of a field are not only costly, but also can damage healthy plants in surrounding areas due to the tire traffic of the replanting operation. Farmers can calculate whether replanting would be profitable for their situation using the Purdue Extension publication AY-264-W, "Estimating Yield and Dollar Returns From Corn Replanting." This publication is available online at http://www.agry.purdue.edu/ext/pubs/AY-264-W.pdf.

"Recognize that the decision to replant ponded areas of fields needs to be made in the context of how much of a grower's original corn and soybean acres remain to be planted," Nielsen said. "Non-planted acres should usually take priority in the remaining planting schedule over the ones to be replanted."

Corn that has recently been planted but has not emerged also is at risk in waterlogged conditions. Nielsen said surface soil crusts may develop after a heavy rain, making it difficult for the corn plant to emerge. Growers should monitor these high-risk areas and be prepared to break up the hardened soil with a rotary hoe to help with emergence.

While standing water in planted fields has some farmers wondering whether or not to replant, others are concerned that soggy fields are delaying planting.

"Some farmers may be thinking about switching from fuller maturity hybrids to earlier maturing ones due to a possible shorter growing season," Nielsen said. "On the other hand, most adapted hybrid maturities can be planted in Indiana until the end of May with little to no risk of fall frost injury to immature grain."

Additional information on other delayed planting issues can be found in Purdue Extension publication AY-312-W, "Delayed Planting & Hybrid Maturity Decisions".

Writer: Jennifer Doup, (765) 494-8406, doupj@purdue.edu

Source: Bob Nielsen, (765) 494-4802, rnielsen@purdue.edu

Ag Communications: (765) 494-2722; Beth Forbes, bforbes@aes.purdue.edu; http://www.agriculture.purdue.edu/AgComm/public/agnews/

Related Web site:
Purdue Extension Farming 2003


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