Sugarbeet Root Maggot Control, St. Thomas, North Dakota, 1972

Insecticides were screened in randomized-complete block tests at 2 locations. The soil was mostly silty clay loam with a pH of approximately 7 and 5-8% organic matter. Beets were planted May 17 and 18. Pre-fly emergence treatments were applied May 19 and 23 and post-fly emergence treatments made on May 31 and June 1. Peak fly emergence occurred on June 7. Plots consisted of four 100 ft rows spaced 22 i n . apart. The insecticides were applied in 7 in . bands over all rows in the plots, and were lightly incorporated into the soil with drag chains (I 3/4 in . links). Applications were made at 3 mph. Weather conditions during the investigations were generally favorable for good beet growth and insecticide application. Significant rain fell after the materials were applied. Data consisted of yields from 30 ft from row 2 (from the left) in each plot at harvest. The data was transformed by x, and analysed by analysis of variance and Duncan's new multiple range test. The functional maggot infestation (based on the amount of damage to beets) in the plots is evidence that there were sufficient numbers of maggots to provide satisfactory data. The ave damage rating is untreated beets was 3.5 (moderate to heavy root damage). The rating scale ranged from 1 (no damage) to 5 (severe damage).