Chicago corn rose for a third consecutive session to hit a seven week high on Wednesday, gaining nearly 5% over two days, as concerns over planting delays in the US.
Soybeans extended their rally from the last session, after US President Donald Trump eased concerns about a US-China tariff war.
The most active corn contract on the Chicago Board of Trade rose 2.2% to $3.76-3/4 a bushel by 10:50am GMT, a price unseen since March 27, after closing up 3.4% in the previous session when prices hit a high of $3.70-3/4 a bushel - their loftiest point since May 3.
Soybeans rose 1.4% to $8.43-1/2 a bushel and wheat was up 1.3% at $4.54-1/2 a bushel.
US farmers seeded 30% of the US 2019 corn crop by Sunday, the government said, lagging the five-year average of 66% as well as the average estimate in a Reuters analyst survey of 35%.
The soybean crop was 9% planted, behind the five-year average of 29% and the average trade estimate of 15%.
"This weather risk is amplified by the large short position speculative funds are holding in corn and beans," said Ole House, director of advisory services at brokerage Ikon Commodities.
"Mind you the corn weather issue is not necessarily a small on." he said.
Soybeans jumped from 10-year lows on Tuesday on optimistic comments from US President Donald Trump.
Trump on Tuesday called the trade war with China "a little squabble" and insisted talks between the world's two largest economies had not collapsed, though investors remained
on guard for a further escalation of tit-for-tat tariffs.
The US soybean processing pace in April was expected to be above last year and the highest ever for the month as soy plants took advantage of good margins and ample supplies of beans, according to analysts polled ahead of a monthly industry report.
Commodity funds were net buyers of CBOT corn, soybean, wheat, soymeal and soy oil futures contracts on Tuesday, traders said.
Trader estimates of net fund buying in corn ranged widely from 30,000 to 70,000 contracts and in soybeans from 13,000 to 30,000 contracts.
News by Reuters, edited by Helen Galgey Checkout. Click subscribe to sign up for the Checkout print edition.