Potatoes, in the form of fries, and ketchup, go hand and hand.

But a side of mustard with those spuds?

For nearly a decade, scientists with the Agricultural Research Service have been studying how plants in the mustard family can be used as part of a more sustainable cropping system.

Researchers with the New England Plant, Soil and Water Laboratory in Orono, Maine, have found that rotating potatoes with canola can reduce soil-borne diseases by 20 percent to 50 percent, according to a new release.

The canola produces naturally occurring sulfur compounds that control powdery scab and Rhizoctonia fungus.

At the Vegetable and Forage Crops Production Research Unit in Prosser, Wash., they found that applying 1 to 2 tons of crushed mustard seed meal per acre significantly reduces weeds.

The mustard seed meal is a biproduct of vegetable oil production.

Potato growers in the Pacific Northwest already use white and brown mustards as cover crops to reduce erosion and plant pathogens.

A side benefit is they produce up to 30 pounds of nitrogen per acre, helping save growers $14 to $30 per acre in fertilizer costs.