US wheat futures rallied 1.7 percent to their highest in nearly four weeks on Tuesday on concerns about sub-zero temperatures damaging the dormant crop in crucial growing areas of the United States, traders said. The gains in wheat spurred increases in corn futures. Soyabeans also closed higher after trading both sides of unchanged during the session.

Traders were also digesting the latest export data from the US Agriculture Department on the first trading day of 2018. Wheat notched its biggest daily percentage gain since Nov. 22 as much of the crop was not protected by a blanket of snow to mitigate the freezing conditions.

Chicago Board of Trade soft red winter wheat for March delivery settled up 6-1/2 cents at $4.33-1/2 a bushel. Prices peaked at $4.36-1/4, matching a level last seen on Dec. 5. CBOT March corn futures ended 2-1/2 cents higher $3.53-1/4 a bushel. CBOT March soyabeans gained 3 cents to close at $9.64-3/4 a bushel.

Ongoing concerns that heat in Argentina will limit the size of that country's harvest supported soyabean prices. A shortfall in South American crop production could boost demand for US exports and help alleviate the glut of domestic supplies following the recent bumper harvest. USDA said on Tuesday morning that weekly US soyabean export inspections were 1.139 million tonnes, in line with forecasts for 1.1 million to 1.3 million tonnes.

Corn export inspections were 683,898 tonnes, also in line with trade estimates that ranged from 575,000 to 800,000 tonnes. Export inspections of wheat totalled 274,506 tonnes, below estimates for 300,000 to 600,000 tonnes.

Copyright Reuters, 2018