1Nova Scotia Agricultural College, Department of Plant and Animal Sciences, PO Box 550 Truro, Nova Scotia, Canada B2N 5E3;
2Nova Scotia Crop Development Institute, Nova Scotia Agricultural College, Department of Plant and Animal Sciences, PO Box 550 Truro, Nova Scotia, Canada B2N 5E3; and
3Mississippi State University, North MS Research and Ext. Center, 5421 Highway 145 South, Verona, MS 38879, USA.