In 1991, Muck Research Station staff conducted and/or cooperated on research projects with researchers of the Departments of Environmental Biology and Horticultural Science at the University of Guelph; researchers from Agriculture Canada research stations at London and Vineland Station; the Ontario Pesticide Residue Testing Laboratory; researchers of the Horticultural Products Laboratory (H. R. I. O.) at Vineland Station, research departments of the Crop Protection Chemical Industry and Growers. This report highlights the research projects which were conducted in 1991.