* Jitters over airliner crash in Ukraine subside
* U.S. wheat yields improving in central Plains
* Corn lower as favorable weather signals big harvest
* Soybeans mixed, turning lower on good crop weather (Updates prices, adds quotes; changes dateline from PARIS/SINGAPORE, changes byline)
By Julie Ingwersen
CHICAGO, July 18 (Reuters) – U.S. wheat futures fell 3 percent on Friday, erasing gains posted a day earlier following the downing of a commercial airliner over eastern Ukraine, while Chicago Board of Trade corn futures also declined and soybeans were steady to lower.
Investors were worried an escalation of the conflict between Ukraine and Russia, both major wheat producers, could affect grain shipments, but those concerns subsided on Friday after Russian President Vladimir Putin called for a ceasefire in eastern Ukraine, where Moscow-backed separatists are fighting.
“Wheat traders … are treating this as a micro event, and they don’t expect it to disrupt any Black Sea wheat exports,” said Robert Bresnahan, president of Trilateral Inc. “And wheat is probably still 20 or 30 cents overpriced, relative to corn,” Bresnahan added.
CBOT corn and wheat both notched four-year lows in the last week, pressured by expectations of rising global inventories.
As of 11:45 a.m. CDT (1645 GMT), CBOT September wheat was down 18-1/2 cents at $5.32-1/4 per bushel. September corn was down 6 cents at $3.73-1/2 a bushel, while August soybeans were up 3/4 of a cent at $11.75-1/2.
Wheat faced additional pressure from rising yields as the U.S. hard red winter wheat harvest moves into the central Plains and away from drought-hit areas farther south.
As well, a spell of warm, dry weather in Europe this week should allow harvesting to accelerate in France, a major exporter.
Corn fell on near-ideal crop weather in the U.S. Midwest that is bolstering expectations for a record-large harvest this autumn. Temperatures are forecast to rise into the 90s Fahrenheit (32 to 35 Celsius) next week in some areas, but were not seen as threatening.
“The recent cool weather has been very favorable for the pollinating corn crop across the Midwest. While some warmer weather is still expected next week, the forecast has trended a bit cooler today and heat stress is not expected,” MDA Weather Services said in a daily note to clients.
The forecast also pressured soybeans, which were paring early gains with about 90 minutes left to trade.
“Weather-wise, everything is pretty good,” Bresnahan said.
For the week, front-month wheat was on track to gain 3.4 percent, its biggest rise since April. Spot corn was down 6.5 percent, its fourth straight weekly decline, and spot soybeans were down 9.4 percent.
Prices at 11:54 a.m. CDT (1654 GMT)
LAST NET PCT YTD
CHG CHG CHG
CBOT corn 373.50 -6.00 -1.6% -11.5%
CBOT soy 1174.25 -0.50 0.0% -10.5%
CBOT meal 378.00 -2.50 -0.7% -13.6%
CBOT soyoil 36.57 0.20 0.6% -5.8%
CBOT wheat 532.25 -18.50 -3.4% -12.1%
(Additional reporting by Naveen Thukral in Singapore and Gus
Trompiz in Paris; Editing by William Hardy and Paul Simao) 
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