Two-thirds Of Iowa Corn Crop Now Safe From Frost

This week's crop conditions report indicates a majority of Iowa's corn is mature enough to withstand a frost. Combines are starting to roll across the state.

Published on: Sep 14, 2010

With some corn and soybean acres starting to be harvested in Iowa, conditions remain mostly good for the 2010 crop. Corn is rapidly maturing and progress remains ahead of normal, as the majority of the corn acres are now safe from frost. Over 62% of the state's corn crop is already mature and safe compared to 34% last week, only 7% last year at this time, and 29% for the 5-year average.

However, concerns about corn stalk condition, stalk rot disease and variable maturity within fields are also being reported in the survey. The weekly weather and crop conditions report was released September 13 by the Iowa office of USDA's National Ag Statistics Service.

Soybeans maturing quickly, as 32% of acres are dropping leaves

Soybeans are also maturing quickly with the aid of recent weather. As many of Iowa's soybean acres are reaching maturity, sudden death syndrome disease is becoming less of a concern for farmers. Alfalfa cutting is winding down for the year, with most of the acres being harvested. Like alfalfa, pasture growth is beginning to slow.

Following a summer of high temperatures and humidity, cooler weather has greeted Iowa the past few weeks, notes Harry Hillaker, state climatologist at the Iowa Department of Agriculture. Last week, average highs were in the upper seventies, with average lows dropping into the low fifties. Along with cooler temperatures, Iowa has had some breezy days that aided crop drying. Also last week, scattered rain fell at various times throughout Iowa, with the northwest corner receiving around two inches. However, most of the state received less than an inch.

Moisture content of the early corn being harvested is 23%

Rainfall amounts weren't enough to keep producers from getting in the field to harvest their 2010 crop. Farmers continued chopping corn for silage and harvesting seed corn, while other farmers began harvesting some early-planted corn and soybeans. Crop condition is 68% good or better for corn statewide. Soybeans across Iowa are rated 69% good to excellent.

Nearly all corn acres have dented, 62% has reached maturity and 3% has been harvested. All three of the categories are 8 days ahead of last year and the 5-year average. Moisture content of all corn in the field is estimated at 27%, while moisture content of corn being harvested is estimated at 23%. Corn lodging is rated 79% none, 17% light, 4% moderate and zero percent heavy. Ear droppage is rated 84% none, 13% light, 3% moderate and zero percent heavy.

For soybeans statewide, 74% of the acres have now turned color, ahead of last year's 59% at this time and the 5-year average of 68%. Leaves have begun to drop in 32% of the state's soybean acres, 4 days ahead of last year and 2 days ahead of the 5-year average.

Compared to last week, alfalfa third cutting has increased 11 percentage points to 92% complete as of September 13, which is ahead of the 80% completed last year and the 5 year average of 85%. All hay condition is rated 5% very poor, 10% poor, 25% fair, 46% good and 14% excellent. Pasture condition is 1% very poor, 5% poor, 25% fair, 50% good and 18% excellent. The mild temperatures have been good for newborn calves and overall livestock condition.

Temperature has influenced corn grain fill in 2010

Iowa's 2010 corn crop has had warmer than normal temperatures since planting. Generally across the state, it's had 100 to 300 more growing-degree days or GDDs accumulated this year compared to normal—based on a planting date of April 10. Up to a third of this increase is attributed to weather in August.

Warm temperatures at night sped up the heat unit accumulation and crop development. Warmer temperatures after tasseling will likely decrease corn yield this year through reductions in kernel weight, says Roger Elmore, Iowa State University extension agronomist. In addition, you can expect lower test weights this year for most of Iowa. Lower test weight corn doesn't store as well as heavier weight corn.

A silver lining in this year's situation is that although the crop is maturing quicker than most farmers have seen in the past several years, this will result in lower grain harvest moistures. The crop has more time for in-field drydown before the day lengths shorten and temperatures decline. Farmers can expect lower grain drying costs this year as a result.

Elmore makes this additional observation: With the expected reductions in corn kernel weight this year, using the typical number of kernels per bushel (90,000 kernels per bushel) to estimate yields will likely result in an overestimation of grain yield.