Hot Time for Silking: Cutting Yields, Maturing Fast

July 28, 2011 03:36 AM

The heat wave across the central and eastern United States threatens to curb yields but also pushes the corn crop to develop fast.

In the week ended July 24, 30 percent of the corn acreage in 18 major producing states started silking. Silking came even faster in Indiana, Iowa, Michigan, Minnesota, Nebraska, and Wisconsin. In the major states, 65 percent of corn acreage had reached the silking stage by July 24, up from 35% a week earlier and the five-year average 69 percent on the same date.

As nearly a third of the corn silked last week, temperatures soared on multiple days into the high 90s in many of the same states.

Whether that damaged crop prospects or mainly hastened development varies locally and with soil types. The impact on crop prospects also is keeping markets on edge.

Tight basis, attractive options
Marketing adviser Kevin Van Trump at FarmDirection, based in Kansas City, says he's helping some producers who sold more of their crop than they now expect to harvest, and others who are looking for the right time to sell.

For those looking to sell, he said, “I think you have to go out now and make some cash sales. The basis is tight in many places and is looking pretty good.”

However, in some growing areas, the crop is developing faster than expected.

“Some elevators and ethanol plants have been backing their bids off,” he said. “They think they may have enough corn to get through” to harvest, which might arrive sooner than expected.

“Producers now are trying to manage their risk rather than capture crazy, high rewards,” he said. Cash market downside risk now may be $1.50, but a bull call spread may limit the risk to 30 cents.

“When you buy calls on a down day, it really is a bargain,” said Van Trump.

Grain elevators in Iowa were paying an average of 19 cents over the September futures contract for cash corn the afternoon of July 25, reported the Iowa Department of Agriculture. Since July 5, the basis had worked its way up from 4 over September. In the same time, the midpoint of western Iowa ethanol plant bids netted a gain of only 1 cent, to 27 over September, according to USDA Grain Market News.

Crop making fast progress
In North Dakota corn fields, “We've been gaining a bit,” said extension agronomist Joel Ransom. “But we still have catch-up to do because half of the crop was planted after May 24.”

Many corn fields received more water than the soil can handle, so they lost a lot of nitrogen. The crop drowned in some areas and crop development varies considerably.

What does North Dakota's corn crop need?

“We need a little more sunshine,” Ransom said. “Not a lot more water, but eventually we will need more water to carry the crop through.” He said temperatures have been a little warmer than normally considered optimal, but conditions are favorable for yields. “It's just that we want to push the heat a little more so the crop will finish.”

Iowa corn risking yield, developing fast
Leaves on corn in some Iowa fields were rolling last week, said Roger Elmore, Iowa State University extension agronomist. “Most of the concerns here are relative to heat,” he said. “Most of our soil moisture has been good enough that we’ve not really had a drought situation.”

In a joint project with Elmore, climatologist Elwynn Taylor of Iowa State suggested that for every four hours of wilting or rolling, corn loses 1% of its yield. “Some of our coarser soils have had three or four days of that,” said Elmore. However, corn on better soils in central Iowa has experienced very little rolling or wilting.

Corn breeders over recent decades have improved timing so silks often are out before corn tassels shed pollen, added Elmore. That provides about a week of buffer time for pollination in case of delayed silking. And silking time doesn't make or break the crop, he said. In 2009, silking was very late – 31 percent of acreage in major corn states on July 19 and 55 percent on July 26 – but yields were excellent.

“The question is more on fill and development after fertilization,” said Elmore. He cautioned against focusing too much on any one time as critical to corn development, because yields may be lost or compensated at many points before harvest.

Even though the heat wave forced some leaf rolling, he said, “high night temperatures have been progressing crop development rapidly.”

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