Iowa's 2013 corn and soybean crops deteriorated some more last week as blistering heat and dryness continued in September. USDA's weekly Iowa Crops & Weather Report was released September 9, a day when temperatures in central Iowa reached 100 degrees. This latest report is based on statewide surveys as of September 8.
"Hot temperatures and lack of moisture continue to stress corn and soybeans as well as pastures and hay ground," notes Greg Thessen, director of the Iowa Office of USDA's National Ag Statistics Service in Des Moines. "Only 35% of the state's corn crop and 33% of soybeans are now rated good or excellent. That's down significantly from the August 5 report when 51% of corn and 52% of soybeans were in those categories. The crop has suffered considerably during the past month."
Some corn plants in Iowa's driest areas and in the driest parts of fields are already dead
The weekly drought monitor this past week showed one-third of Iowa was in severe to moderate drought. "These crops in a widening area of Iowa are under a lot of stress and some of these cornfields in central Iowa are shutting down, they're dying," says Mark Johnson, Iowa State University Extension field agronomist. Depending on the water holding capacity of the soil, some areas of fields are already dead as plants have run out of water. If soil has any compaction issues or rootworm problems, the stress on the corn plants is magnified. "We had such a tiny amount of rain here in July and August, that the plants in the driest parts of some fields are dead," he says.~~~PAGE_BREAK_HERE~~~
Some corn is forming a premature black layer in the kernel tips. The black layer is the first visible sign that a corn plant has reached maturity. "These plants that are putting in a black layer prematurely are dying, so no more nutrients are going to enter those kernels," says Johnson. "These kernels won't get any fuller than they are right now, once they reach maturity. We have large patches within fields that are noticeably worse than the rest of the field. As this heat and lack of rain continues these areas in fields where corn is dying grow wider. With this stress on corn plants during the grain filling period, the kernels aren't as deep as they normally are. The kernels should be wider, thicker and longer. We should have bigger kernels—if this were a normal year."
On September 8 only 5% of Iowa corn crop was rated as mature, just over two weeks behind normal
CROP REPORT: Iowa experienced warmer and drier than normal weather during the week ending September 8, 2013, according to USDA's National Agricultural Statistics Service, which conducts the weekly survey. Some rain fell in the western part of the state, but most areas continued to be dry. Hot temperatures pushed crops to mature, but crop conditions are showing stress from the heat and lack of precipitation. Statewide there were 6.8 days suitable for fieldwork.
As of September 8 topsoil moisture levels on average statewide rated 52% very short, 33% short, 15% adequate and zero percent surplus. Subsoil moisture levels rated 41% very short, 40% short, 19% adequate and zero percent surplus. Topsoil moisture was considered very short on over 50% of the acreage in the southern two-thirds of Iowa.~~~PAGE_BREAK_HERE~~~
With nearly all the corn crop in or past the milk stage, 86% of the crop reached the dough stage, trailing the normal 93%. Fifty-four percent of the crop has reached the dent stage, 24 percentage points behind normal. Only 5% of corn was mature, just over two weeks behind normal. Corn condition declined slightly and rated 9% very poor, 19% poor, 37% fair, 31% good and 4% excellent. With almost the entire soybean crop setting pods, 12% has begun turning color. Some of the earliest planted soybeans have begun to drop leaves. Soybean condition also declined and was rated 10% very poor, 20% poor, 37% fair, 30% good and 3% excellent.
The harvest of third cutting alfalfa was 84% complete, slightly ahead of the normal 82%, but still behind last year's 100%. Pasture condition continued to deteriorate, and was rated 30% very poor, 32% poor, 29% fair, 8% good and 1% excellent.
IOWA PRELIMINARY WEATHER SUMMARY—for week ending September 8, 2013
By Harry Hillaker, State Climatologist, Iowa Department of Agriculture & Land Stewardship
Iowa recorded another warm and dry week. Temperatures managed to fall below normal on Monday (Sept. 2) and Tuesday (Sept. 3) but were well above normal in most areas the rest of the week. Cresco and Williamsburg reported the lowest temperatures of the week with Tuesday morning lows of 41 degrees. Saturday (Sept. 6) was the hottest day with highs reaching 100 degrees at Lamoni, Knoxville and Osceola although cloud cover held highs to the mid-80's over parts of northwest and northeast Iowa. Temperatures for the week as a whole averaged 4.3 degrees above normal.
Temperatures for the week averaged 4.3 degrees above normal, and last week was the driest week since mid-January for Iowa
The only rain of consequence came on Wednesday night into Thursday morning over the western one-third of the state. Little Sioux in Harrison County reported the most rain with 1.25 inches. However, rain of more than one-half inch was confined to parts of Woodbury, Monona and Harrison counties. Otherwise there were some isolated light showers over far southern Iowa on Sunday (Sept. 1) morning and scattered brief light showers across the state on Friday (Sept. 6) and Saturday (Sept. 7). Much of the eastern two-thirds of Iowa received no measurable rain during the week. The statewide average precipitation was only 0.04 inch while normal for the week is 0.84 inches. A drier week has not been recorded since mid-January.