Washington ? Farmers will grow fewer soybeans this year because of the rapidly spreading Asian rust disease and low prices, the Agriculture Department predicted Thursday.

Growers will plant less wheat, more cotton and more corn than they did in 2004, the department said in its prospective plantings report.

Concerned about whether farmers are aware of Asian rust, the department surveyed 68,000 farms in the 31 states where soybeans are produced. Nine in 10 soybean growers said they knew about the disease.

Still, only one in 10 farmers said it factored into their planting decisions. Of those, half said they would reduce their soybean plantings. The disease spreads in reddish-brown blotches on growing leaves, weakening the plant and reducing farmers’ yields.

The nation’s wheat-planted area also will drop by 2 percent, the department said, a decline that would make this year’s acreage the lowest since 1972. According to the projections, farmers will plant 4 percent less winter wheat, the type that dominates U.S. wheat production.

Corn-planted area is expected to grow by 1 percent over 2004, which would make this year’s acreage the largest since 1985. Growers will plant more corn in the Corn Belt and southern Great Plains but will plant fewer acres in the Delta, Southeast and Northern Great plains, where low prices and high fuel and fertilizer costs have producers shifting to more profitable crops.

Cotton acreage also is projected to grow by 1 percent over last year.