US corn futures rose on Thursday for a fourth straight session as dismal weather forecasts signalled further planting delays in the Midwest, prompting commodity funds to cover short positions, analysts said.
Chicago wheat futures hit a one-month high, led by corn, and soyabeans followed the firm trend.
As of 12:53 p.m. CDT (1753 GMT), Chicago Board of Trade July corn was up 7-1/2 cents at $3.77 per bushel, after reaching $3.80-3/4, its highest since March 29.
CBOT July wheat was up 15-1/4 cents at $4.64 a bushel after reaching $4.68, its highest since April 12, and July soyabeans were up 1-1/2 cents at $8.37 a bushel.
Corn remained the focus of the market as the outlook for rain over much of the next 10 days threatened to stall field work, which is already behind schedule.
Farmers had seeded 30% of the US 2019 corn crop by Sunday, the US Department of Agriculture (USDA) said on Monday, well behind a five-year average of 66%.
The weather problems come at a time when commodity funds have built up massive net short positions in corn, soyabean and wheat futures, leaving the markets vulnerable to bouts of short-covering.
Soyabeans followed corn higher but gains were capped by expectations that planting delays could prompt farmers to switch some acres intended for corn to soyabeans. Ample soya inventories from last season also hung over the market.
CBOT wheat futures posted the biggest gains of the three grains, but analysts attributed the strength in wheat to technical strength and short-covering, rather than fresh demand or threats to supply.