Replant Risks, Rewards

April 28, 2012 12:22 AM

What early planting may mean to this year’s crop

Many farmers rolled the proverbial dice and planted their corn crop early this spring—some nearly a month early. Positive pricing potential for selling August old-crop corn and ideal weather conditions influenced their decision.

As May starts to unfurl, those farmers are waiting to see if their gamble pays off. For some it will, for others it won’t, says Ken Ferrie, Farm Journal Field Agronomist, based in Heyworth, Ill.
"Every year, a dozen farmers in our area face a replanting decision, and I expect that this year as well," he says.

A cold snap could stall corn emergence or growth and pave the way for insect problems. "While still in the ground, corn is burning up its food supply and giving off CO2 emissions, which is what wireworms and other insects are attracted to," Ferrie explains. "You may then have cool-season water molds to deal with as well."

Worse yet, a killing frost could force farmers to replant their corn crop or shift to another crop, most likely soybeans. Killing frosts are particularly damaging to larger corn, which may have its growing points emerged.

"Corn is more likely to recover during earlier stages of growth, but as it matures into V4 and beyond, there are fewer reserves left in the seed to support regrowth of the plant," says Brad Miller, Ohio territory agronomist for DeKalb. "If a freeze is severe enough, it could kill the growing point even while beneath the soil surface."

Ferrie advises farmers who are faced with a replanting decision to think the process through before taking action.

"Try to take the emotion out of your decision making; get down to the numbers and let them help you decide what to do," he says. "You don’t want to tear up what might be a 170-bu.-per-acre crop to produce a 160-bu. crop."

That advice is more pertinent than usual this spring, as many premium corn hybrids are in tight supply.

"If you got the best products for your farm the first time around, you were fortunate. You may not be able to get them a second time," says Jeff Hartz, director of marketing for Wyffels Hybrids in Geneseo, Ill.

Josh St. Peters, corn marketing manager for Pioneer Hi-Bred, adds: "The initial hybrid may not be available for replant, but we have other quality seed available."

There were seed production challenges this year. Some winter production sites in South America experienced heat stress at pollination, which undercut seed quality and yields. Transportation problems also played havoc with availability this spring, as companies struggled to get seed corn back to the U.S. and delivered in a timely fashion.

A logical strategy. Ferrie tells farmers to start by assessing what their current crop will yield versus what a replanted crop is likely to yield. This involves evaluating the corn stand and total plant populations in each field.

"What you’re looking for is uniformity of corn growth in your fields," Ferrie says. "You want to look at each plant within the row to see if it can put on a viable ear; uniform growth means more plants will be able to do that."

He explains how poor uniformity impacts growth and development: "Say you have 26,000 corn plants per acre, of which 24,000 are at the three-collar stage and 2,000 are at less than the two-collar stage. Those 2,000 late emergers won’t put on a viable ear and are essentially weeds in the field."

Ferrie also looks at genetics. "Every hybrid flexes, but how much each will flex varies," he says. "Some flex in length, some flex in girth and most just flex in kernel depth so you get a bigger ear with the same amount of kernels. If you lose stand, a flex hybrid will often fill in the gaps. However, if a fixed-ear type loses plant count, it won’t be as easy to pick up the slack."

Farmers will need to kill their existing corn stand prior to replanting. "If it’s a Roundup Ready corn field, you’ll need to use something like Fusillade or Select to kill it, or you may need to till it under. If you spray the stand, you will face a time lag before you can plant that field again," Ferrie says.

"The cost of replanting a damaged field often makes or breaks a replanting decision," says Bob Nielsen, a Purdue University Extension agronomist. "This includes seed, fuel [tillage and planting] and additional pesticides and dryer fuel."

Nielsen’s guide "Estimating Yield and Dollar Returns from Corn Replanting" offers a step-by-step
procedure for determining if replanting is economical. It is available online at

Crop insurance dates also figure into the financial considerations for farmers who want to replant.
"If it’s the first of May and you have only 25,000 viable plants left from the 36,000 per acre you planted, and you have access to plenty of moisture, plenty of seed and $6 corn, then you might want to replant," Ferrie says.

Farmers who opt to replant corn will need to scout those replanted fields at pollination, in late June or early July. "They will pollinate later than fields not replanted," Ferrie says, "making them vulnerable to increased pressure from pests, including Japanese beetles and rootworm beetles. Be proactive and keep an eye on them."


Use Stand Counts to Estimate Yield Potential

Final corn plant stands are a good indication of the yields you can anticipate at harvest and can help you evaluate fields for replanting. Here is a formula to help you estimate stand counts.

Use a tape measure to mark off 17'5" in a row of corn planted in 30" rows. (Use the table below to determine row length in spacings other than 30" rows.) Count the number of corn plants in the measured-off space, and subtract any plants unlikely to produce a good ear.

Take your plant count and multiply it by 1,000 to get your anticipated total plants per acre. For instance, if you count 36 plants, you can anticipate a final stand count of 36,000 plants per acre. If each of those plants produces a viable ear, that equals 36,000 ears per acre. Farm Journal Field Agronomist Ken Ferrie estimates that for every 1,000 good ears of corn grown, farmers will harvest 5 bu. to 7 bu. That means you would harvest 180 bu. to 252 bu. per acre. Here’s the equation:

36 plants × 1,000 = 36,000 plants per acre
36,000 × 5 = 180 bu. of corn per acre
36,000 × 7 = 252 bu. of corn per acre

Use this counting process in four or five different locations within each field. Then average the numbers to arrive at a yield estimate for the field.


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Spell Check

4/28/2012 06:56 AM

  We tore up 70 acres as it was uneven and had many buggywhip plants due to a frost at spike. we feel we still have a good shot at 200 bu with a new stand the old stand maybe 160

4/28/2012 06:56 AM

  We tore up 70 acres as it was uneven and had many buggywhip plants due to a frost at spike. we feel we still have a good shot at 200 bu with a new stand the old stand maybe 160


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