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The trial was located at the Northwest Experiment Station, Crookston, Minn. The major objective of the 1987 insecticide trials was to compare at-plant-and-time-of-emergence soil systemic treatments in dryland sites (Crookston, Minn., and Grand Forks, N. Dak.) and irrigated locations (Park Rapids and Brooten, Minn.). Soil systemic treatments were present at each site with various combinations of foliars. CPB are at least 100-fold resistant to Pydrin and 40-fold resistant to Ambush + Pounce at this location. Plots were 4 40-inch rows 25 ft long. Treatments were replicated 4 times and were arranged in a randomized complete block design. B-size Norchip seed was planted on 5 May and planting treatments of Temik and Thimet applied over the row. The soil was a clay type, permitting granules to fall into soil openings along the planting ridge. Soil moisture was very good. Emergence treatments were applied on 29 May when potato plants were 2 inches high. Soil was cultivated over the emergence treatment. Wintering CPB adults were present in higher than normal numbers on this date. Foliars were applied on 20 and 28 Jun, 10 and 22 Jul, and 8 Aug according to an experimental plan of 1, 3, and 5 foliars. Foliars applied over the emergence soil systemic were applied 20 Jun and 8 Aug. Adult emergence from an adjacent potato plot threatened to overwhelm these studies in July (note adult defoliation column in table). Thus, we waited for modest second-generation oviposition and then treated the entire study with 0.5 lb (AI)/acre of Penncap-M on 24 Jul. Three applications of fungicide were applied independently of insecticides. Yields were taken from the center 2 plot rows, graded #1 and B-size, weighed, and recorded.

On 8 May, a cooperative trial with Sigco Research was established in Pennington county near St. Hilaire, MN. Plot size were six 38.1 cm rows, 6.10 m in length, planted with a cone type 6-row planter. The trial was arranged in a randomized complete block design, replicated 4 times. All granular treatments were applied with the seed. All foliar treatments were broadcast applied in 30.4 liter/ha material at 2.8 kg/cm2 pressure using a hand held C02 sprayer. Two foliar applications were made at late pre bloom and early post bloom. Data on stand density, vigor, and lodging were collected. Plant heights were recorded pre bloom. Plots were threshed, moisture and plot yield recorded, and final yields adjusted for moisture.

A cooperative study was arranged with Sigco Research, Inc. of Breckenridge, MN. The trial was planted at Cando, ND, on 10 May using a cone type 6 row planter. Plots were 6-15 inch rows 20 ft in length arranged in a randomized complete block design replicated 4 times. All insecticides except foliars were seeded with the seed. Foliars were applied on 21 May and 4 Jun using a CO2 sprayer. Total material per acre was approximately 17 gal. Soil type was a well drained silt loam. Weather conditions were very hot and dry throughout the growing season. All readings except yield were made 4 Jun. Plots were harvested on 6 Sep.