Colorado Potato Beetle Control with Admire (Imidacloprid), 1994

Abstract

Abstract Experimental plots were established on the Ul Research and Extension Center, Kimberly, Idaho. Potatoes were planted 21 Apr and irrigated by solid set sprinkler. The soil type was Portneuf silt loam. Four placement methods, and one untreated check plot were replicated four times in a randomized complete block design. Individual treatment plots were 4 rows (36 inch row spacing) wide by 25 ft long with 5 ft alleyways separating the plots. All four placement application methods of the emulsifiable concentrate (2EC) were tested at a single rate of 0.25 lb AI per acre. The first placement was applied at the time of row marking, one wk prior to planting, on 14 Apr using a shank application (Shank AP) approximately three inches deep on either side of the anticipated seed piece location. The second method was an in-furrow spray application over the seed piece at planting (Over seed AP). The third method was a six-inch banded spray over the row at planting and prior to bedding (Over row AP). The fourth application method was a shank application approximately three inches on either side of and two to three inches below the seed piece (Shank PP). The second and third application methods were made at planting on 21 Apr. Due to weather constraints, application method four was made on 3 May. On a weekly basis, egg masses, small larvae (1-2 instar), large larvae (3-4 instar) and adult beetles were counted and percent defoliation estimates were made from whole plant inspections of the center five hills of the center two plot rows. Counts of green peach aphids were made on 20, 26 Jul and 3 Aug by examining 10 leaves from each plot. Plots were harvested (25 row ft) on 11 Oct for yield and grade. Wireworm feeding was also evaluated at this time by examining 50 randomly selected tubers for damage. Data were analyzed using ANOVA and Tukey’s multiple means comparison. Natural Colorado potato beetle populations were virtually nonexistent except for patchy collections of a few adults and egg masses. Twenty adults were transferred to each plot on 14 and 15 Jun and again on 20 and 21 Jun. Counts made of all stages of CPBs at this time indicated that populations remained low and patchy. Volunteer potatoes containing CPB larvae were then collected on 27 and 28 Jun and again on 1 Jul from an adjacent field at the UI Research and Extension Center and transferred to each test plot. Counts made of all stages of CPB on 7 Jul indicated a more even distribution of all life stages within the untreated check plots.