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Decision time arrives

for drought-affected corn

Aug. 2, 2012 | 0 comments

With the arrival of August, decision time is at hand for what to do with corn that has been affected at various degrees by the drought, according to University of Wisconsin Extension Service Corn Agronomist Joe Lauer.

After rains returned to many but not all parts of the state during the third week of July, Lauer spoke to a crowd of 60 attendees at the July 31 field meeting of the Fond du Lac and Dodge County corn growers association.

Making a decision on the fate of one's corn crop is possible now because the pollination period should soon be completed in most areas, Lauer pointed out. This means it is possible to check the ears for the kernel fertilization that sets the stage for the potential grain yield, he explained.

He said corn plant height is not necessarily closely tied to grain yields.

In Wisconsin's southern tiers of counties, some corn growers have already pulled the plug on this year's corn crop by harvesting the crop for forage, Lauer noted. Noting that four inches of rain have fallen sicne July 20 at Arlington and in other parts of the state which were the most seriously affected by the drought, he believes this was perhaps a rush to judgment.

What's significant about the ability of corn plants to produce grain is the vitality of the leaf immediately below the ear and that of the other leaves just below and above it, Lauer observed.

He said the leaf just below the ear accounts for about 60 percent of the grain production over a period of about 40 days at rates of 4-5 bushels daily per acre during good growing conditions. This assumes that kernel set has occurred, Lauer indicated.

Taking the Shake Test

An early test of fertilization is known as the "shake test," he noted.

This involves a careful cutting or unraveling of the leaves of the young ear shortly after the period of pollination, which can run for up to 11 days, but which can be restricted to 2-3 days during stress from drought, Lauer remarked.

He demonstrated that test at the field day meeting here.

Once the leaves are removed, the ear is to be shaken. If the silks separate from the ovule, this means that fertilization has occurred. If the silks cling, fertilization is still possible provided that pollen, which can ordinarily travel for up to 50 feet, is still available, Lauer stated.

Corn growers in the crowd indicated that some of their fields have significant variability in the stage of corn development and between areas with barely sufficient moisture and serious shortages.

Lauer pointed out that variability in maturity could be an advantage during times of stress because of the differing periods of pollination, which occurs best in the morning and which shuts down once the temperature tops 94 degrees. This is a reason for planting corn of differing maturities in adjacent fields, he noted.

Kernel Count in Blister Test

A more reliable indication of potential yield is the blister test, Lauer continued. This allows a counting of the kernels on the ear and provides a base number from which to calculate potential yields.

In the Extension Service plots at Arlington, Lauer is pleased to see corn ears with up to 16 rows of corn and total kernel counts approaching 600 per ear. He noted that the kernel numbers built gradually as the pollination period wound to a close.

Another crucial time is the 10 days following pollination because this is when cell division occurs, Lauer explained. This goes a long way toward determining test weights, he said.

Once the chance for pollination expires, there's enough evidence to make a decision about one's crop, Lauer stated. With a high kernel set, the decision is easy because it means proceeding as normal with the crop, he noted.

Even with a 50 percent or a bit higher kernel set, there's reason to let the crop grow to maturity, Lauer advised. Whether harvested for silage or grain, that corn will have a boost in yield by the development of the amount of grain that is present, he observed.

Barren Corn in August

A more difficult decision awaits those whose corn is definitely barren by the first week of August, Lauer acknowledged.

He listed the two choices as plowing the crop under or harvesting it for silage.

In southern Wisconsin, some 20-30 percent of corn fields will not have a grain yield, Lauer estimated. On the other hand, he reported that the corn surrounding the Twin Cities area of Minnesota is fantastic this year.

Regarding the quality of silage, Lauer pointed out the peak stages are at flowering (too late in most of this year's drought-affected corn) and again at the physiological maturity and moisture level (about 65 percent) at which corn is ordinarily harvested as silage. He said that time usually occurs about 42-47 days after the pollination period.

Even with barren corn on which the stalks are still alive, photosynthesis and the production of sugar, then stored in the stalks rather than going to the grain, will continue, Lauer pointed out.

He noted that most areas have at least two more months before a killing freeze is likely.

With barren corn, the keys are to await until whole plant moisture reaches about 65 percent and to chop or disc bine the stand, although the latter brings the risk of pulling in ash, Lauer observed.

He cautions against harvesting the corn as baleage.

The dry weather which prevailed as the corn plants completed their vegetative growth restricted the development of brace roots, which makes the corn more vulnerable to lodging, Lauer pointed out. He added, however, that corn with high grain yields is also prone to lodging.

In a normal year, dry matter silage yields should run at eight or more tons per acre, Lauer noted. This year, however, he said many growers will have to be satisfied with yields approaching one-half of that amount.

Crop Insurance Claims

Regardless of the decision on when to harvest this year's corn, be sure to make arrangements with the crop insurance adjuster so claims for losses can be documented and honored, Lauer reminded growers.

Indications are that each crop insurance company will handle the unusual situation somewhat differently, but that each one is likely to tell the growers what strip of rows to leave standing for the yield determination rather than having the grower choose what rows to leave for the insurance adjuster.

In most cases, an insurance company representative predicted, it is likely that the yield adjustments will be made on the condition of the corn shortly after Labor Day. Because all adjusters are likely to be extremely busy this year, corn growers were urged to be early in scheduling a visit and filing for claims.

On a related point, all growers were encouraged to document their silage and grain yields, although there is no federal crop disaster relief program in place at the moment. Because of the possibility that a drought relief program might be approved, growers will need yield documentation to present to their county Farm Service Agency office in order to establish a loss claim.

Wisconsin Corn Growers Association Executive Director Bob Oleson of Palmyra told the attendees that the corn growers who planted early this year are enduring the worst hammering from the drought. This includes the crops that his family was growing in Walworth and Jefferson counties.

Two special meetings on the drought held recently at Janesville and Waunakee attracted a total turnout of 400, Oleson reported.

During his two days at the association's booth at the 2012 Farm Technology Days in Outagamie County, he said one-half of the farmers he talked to did not expect to be affected by this year's drought. But he said their opinion changed a bit when he reminded them of what it would probably cost to buy any corn to feed their livestock.

Oleson said the National Corn Growers Association is not going to ask the federal government to relax the Renewal Fuel Standards of a 10 percent ethanol component of gasoline in order to ease the demand on the supply of corn.

An ethanol plant representative told the attendees that some plants will be cutting back on production, others will shut down for brief periods, and a few are likely to be forced out of business as a result of high corn prices and possible difficulty in obtaining a supply.

Corn Yield Contests

Corn yield contests overseen by local associations such as Fond du Lac, Dodge, Columbia, Juneau, Adams and Marquette counties and for the remainder of the state will continue as usual, Oleson announced.

He reported that the entries in the national corn yield contests for this year have broken the record of 6,000 set in 2011 and noted that in the Wisconsin contests some corn seed companies will match the cash prizes awarded by the corn grower associations for the top yields.

Fond du Lac County Extension Service crops and soils agent Mike Rankin pointed out that the county posted the top average corn yield among the state's counties in 2011. The year's average of 177 bushels per acre was an increase of four bushels from 2010 and was 21 bushels above the third highest average yield in the county, he noted.

When Rankin asked the attendees for what the average grain yields would be in the two counties for this year, no more than one-third of them expected the yields to be above 130 bushels per acre.

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