Effect of Insecticides and He rbicides on S u garbeet Establishment, Yield and Control of t he S ugarbeet Root Ma g got *

The sugarbeet root maggot, Tet a nops myopaeformi s (Roder), can be a serious problem in sugarbeet production areas of We s tern Canada (2,5) and the United States (9,1 0 ,13). Infestations of the sugarbeet root maggot are sporadic and, during years of severe infestations, can re­ duce sugarbeet yield by over 50%. The biology of the sugarbeet root maggot has been re­ viewed by Hawley (7), Knowlton (8), Harper (6), and Whit­ field (11). Whitfield et al. (12) published a bibliogra­ phy that included papers on the control of the sugarbeet root maggot. Use of chemical insecticides is the only sat i sfactory method of reducing damaging populations. Harper (6) repor t ed that the sugarbeet root maggot adult lays its eggs close to the root of the young plant, and thus a practical, effective, and economical method of con­ trolling this pest has consisted of applying granular in­ secticides into the seed furrow at planting time to kill the newly emerged larvae (2,5). It is known that some in­ secticides applied close to the seed may be phytotoxic (1,2,5). In this paper, we report on a series of field experiments conducted between 1970 and 1982 to evaluate the insecticidal and phytotoxic properties of several granular insecticides applied in-furrow, and the interac­ tion of several of these with commonly used soil-applied herbicides.