CHICAGO, April 15 (Reuters) - U.S. corn futures closed mixed on Thursday, with the most-active contract easing on pressure from commercial hedging after spiking above $6 a bushel for the first time since June 2013 during overnight trading.

But concerns about seeding delays due to cold weather in the U.S. Midwest lifted new-crop corn contracts.

Weather worries also underpinned wheat futures, which rose for the third day in a row to their highest since early March as dryness in the U.S. Plains raised concerns about harvest prospects.

Soybean futures were firm too. Traders said prices need to rise compared to corn to entice U.S. farmers to plant more acres.

Overnight strength in corn triggered some country movement after the market hit targets that farmers had left with grain dealers.

"There was a little bit more farmer selling once corn hit $6, which makes sense," said Jim Gerlach, president of U.S. broker A/C Trading.

Additionally, a U.S. Agriculture Department report that showed weekly export sales of corn falling below market expectations added pressure to prices for the yellow grain.

CBOT May corn futures settled down 4 cents at $5.90 after peaking at $6.01-1/2 a bushel. New-crop December rose 1 cent to $5.12-1/4.

A U.S. Agriculture Department report that showed weekly corn export sales falling below market expectations added pressure.

CBOT May soybeans were 8-1/4 cents higher at $14.18-1/4 a bushel and CBOT May soft red winter wheat was up 5-3/4 cents at $6.53-3/4 a bushel.

Dry weather and a cold surge expected next week poses risk of damage to the U.S. wheat crop.

"The cold has commenced, with temperatures down to freezing overnight over the northern plains, and due to get there tomorrow morning over the eastern belt," Charlie Sernatinger, global head of grain futures at ED&F Man Capital, said in a note to clients. (Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Marguerita Choy and Jonathan Oatis)