Mustard Green Manure Use in Eastern Washington State

In the irrigated region of Eastern Washington State, the use of mustard green manures in potato production has grown from 720 ha in 1999 to over 12,000 ha in 2010. Farmers are using the practice mainly before potatoes, and primarily for soil quality benefits. However, the practice has also shown potential for management of soilborne pests, including Verticillium dahliae and parasitic nematodes (Meloidogyne chitwoodi and M. hapla). Research has confirmed these pest related benefits in a short wheat-potato rotation but results have been inconsistent in other rotations after a single green manure crop. Because of the low organic matter soils in this region, farmers are finding the soil quality benefits, such as increased infiltration rates and resistance to wind erosion, to be of greater value than the pest control benefits. Ongoing research to determine the pest suppression mechanisms of the practice holds promise of greater use and benefits to potato production in this region.