Among the Midwest states hardest hit by drought at the moment are Illinois and Indiana, which rank second and fifth in corn output. In each state, less than 40 percent of the young corn crop is now rated in good to excellent condition.
Counter-balancing this concern for overall U.S. production are much better rated crop conditions currently in other key areas of the Midwest including top producer Iowa and Minnesota, which just received some rain, and Nebraska where about 40 percent of the corn is irrigated.
Nielsen said 2012 is shaping up as "a perfect storm" for Indiana that will threaten this year's corn crop. His current worry: persistent drought conditions coupled with a forecast for extreme heat and little moisture over the next seven to 10 days as Indiana's corn crop pollinates.
The National Weather Service is calling for above-normal temperatures and below-normal precipitation for the next six to 10 days from Ohio to Nebraska, southward to Missouri. Highs on Wednesday were 100 F in Des Moines, Iowa; 102 in Omaha; and 93 in Champaign, Ill.
Summer of 1988 versus 2012
Crop watchers say that despite similar fears 2012 is far from an exact match of 1988. Conditions were drier, for example, for the April to June quarter in 1988 compared with 2012, so the stress was earlier in the crop cycle, crop experts say.
This year the extreme drought conditions so far are in a smaller chunk of the belt, specifically the southern tips of Indiana and Illinois and southeast Missouri. These areas currently have the same rain deficits as in 1988. Rain in July will be absolutely key to the corn crop's fate: in 1988 rainfall during the spring to early summer was some 8 to 10 inches below normal, according to the Midwest Climate Center.
Heat also matters, as the corn plant stops growing when temperatures go above 90 degrees. So far, 2012 has been hotter across a broader swathe of the Midwest than 1988. For instance, the average temperature from April to June in Indiana has been nearly 2 degrees above 1988.
"It does not mean that conditions cannot become as serious as they were in 1988," said Elwynn Taylor, climatologist for Iowa State University. "It's just that most of the damage to the crop in 1988 was done in May and June. This year June will be ending with the majority of the crop still considered in good condition."
Emerson Nafziger, an agronomist with the University of Illinois, said his biggest fear is that many farmers in the southern areas of the Midwest have already thrown in the towel and halted fieldwork, irrigation, spraying and so on.
"Rain is the only thing we need on this crop. There isn't a lot of things we can go out and do to fix it," Nafziger said. "People aren't willing to spend any money if they are already into an insurance claim, and many of them are."
There are reports were corn in southern Illinois is only 2 to 3 feet tall and tasseling, he said. "That's a field that is not going to produce a yield."
(Reporting by Christine Stebbins. Editing by Peter Bohan and Bob Burgdorfer)