Yields may be reduced | Development of late seeded crops is catching up but maturity of corn is still a month away
CHICAGO (Reuters) — Warm, humid, late-summer weather across the central United States is speeding the development of corn and soybeans.
The favourable conditions have eased concerns about potential yield losses due to frost for this year’s late planted crop.
About 10 percent of the projected record corn crop was seen at risk in early September, based on U.S. Department of Agriculture weekly data, but that was expected to fall as the month progressed.
“Warmer-than-average temperatures in the last half of August allowed us to catch up on heat units — growing degree days — and pushed crop development,” said Iowa State University agronomist Roger Elmore, referring to corn in Iowa as of the last week of August.
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“GDDs were 120 to 130 percent of normal across the state, but frost and drought and heat are still concerns.”
Corn and soybean development have lagged the average all summer after a wet, cool spring delayed planting for up to a month in some areas. Crops were catching up in late August and early September, especially soybeans, according to the USDA.
“One of the few good things about the heat, it’s helped corn speed up development per day, but I think we’ve been losing yield on the back end,” said Bob Nielsen, an agronomist with Purdue University in Indiana.
Near-term forecasts still call for more warm, dry conditions for the upper Midwest.
“Even the longer range forecast looking all the way out to early October isn’t showing any frost risk. It’s a pretty warm pattern,” said Joel Widenor, senior agricultural forecaster with Commodity Weather Group.
The National Weather Service’s 30-day outlook for September calls for above-normal temperatures. NWS releases its next 30-day outlook for October Sept. 19.
Even so, frost risk remains in the big corn states of Iowa, Minnesota, North Dakota and Wisconsin, where crops are well behind average. In those states, 27 to 39 percent of corn had not reached the dough growth stage by Sept. 1, which is when the kernel is soft and maturity about seven weeks away.
That equated to a frost risk for 1.3 billion bushels of corn, or 10 percent of the expected record 13.76 billion bushel U.S. corn harvest.
On average, the first killing frost comes by mid-October in Iowa and by the first week in October in North Dakota, Minnesota and Wisconsin.
A killing frost is defined as temperatures staying below -2 C for four hours or more. Plants shut down at that point, preventing immature corn kernels from filling completely and translating to a lower final test weight at harvest.
For soybeans, the bigger concern from coolness or frost is lower oil content.
However, the recent heat wave has also been weighing on overall soybean pod development, which sparked a rally in Chicago Board of Trade soybeans markets.
