Potatoes were planted 19 May, at the University of Minnesota Northwest Experiment Station, Crookston, MN and the Red River Valley Potato Growers Association Research Farm, Grand Forks, ND. Research plots were of variable length with 36-inch row spacing, randomized in complete blocks with 3 replications. Pretreatment counts were made by counting all 2nd through 4th instar larvae on sufficient plants to yield a minimum of 200 larvae per replication. One insecticide spray was applied 30 Jun, with a C02 powered hand sprayer deUvering 36 gal of water/acre. Percent control was based on pretreatment counts for the first evaluation, and in comparison to the untreated control plots for the second evaluation.
Potatoes were planted 24 May, at the University of Minnesota Agricultural Experiment Station, Rosemount MN. Plots were 40 ft long, with 40 inch row spacing, randomized in complete blocks with 3 replications. Insect numbers were estimated by counting nymphs on the underside of 30 leaves per plot. Foliar sprays were applied using a C02 powered hand-sprayer delivering 36 gal of water/acre at 35 psi. Treatments were applied 27 Jul, and evaluations were made 7 days posttreatment.
Potatoes were planted 18 May, at the Red River Valley Potato Growers Research Farm (RRVPGA), Grand Forks, ND. Plots were of variable length with 38-inch row spacing, randomized in complete blocks with 3 replications. All beetle larvae were counted on every plant in each replication until a minimum of 200 larvae were found. Insecticide treatments were applied using a CO2 powered hand-sprayer delivering 50 gal water/acre at 35 psi. Treatments were applied 7 Jul and evaluated 24 h later on 8 Jul. Subsequent evaluations were not possible because of the aerial application of insecticide to the entire field on 9 Jul.
Potatoes were planted 6 May, at the University of Minnesota Northwest Experiment Station, Crookston, MN and at the Red River Valley Potato Growers Association Research Farm, Grand Forks, ND. Plots were of variable length with 38-inch row spacing, randomized in complete blocks with 3 replications. Pretreatment counts were made by counting all 2nd through 4th instars on sufficient plants to yield a minimum of 200 larvae per plot. At Crookston, most larvae were 3rd and 4th instar, at Grand Forks, most larvae were 2nd or 3rd instar. Insecticide sprays were applied using a CO2 powered hand-sprayer delivering 36 gal of water at 35 psi. At Crookston, beetle counts were made 9 Jul, 10 Jul and 15 Jul; foliar sprays were applied 9 Jul immediately after the pretreatment count. At Grand Forks, counts were made 1 Jul, 8 Jul, 10 Jul and 16 Jul; Bacillus thuringiensis and the insect growth regulators were applied 1 Jul and 9 Jul, the conventional insecticides were applied on 9 Jul only. Two untreated controls were included at both locations. Percent control was based on pretreatment and posttreatment counts for each plot.
Potatoes were planted 24 May, at the University of Minnesota Agricultural Experiment Station, Rosemount MN. Treatments were 20 ft long, with 40-inch row spacing, randomized in complete blocks with 3 replications. Insect numbers were estimated by counting nymphs on the underside of 35 leaves per plot. Foliar sprays were applied using a CO2 powered hand-sprayer delivering 36 gal of water/acre at 35 psi. Treatments were applied 22 Jul and 30 Jul. Percent control was calculated by comparison of treatment counts to those for the untreated control.
Certified B-size potatoes were planted 29 May at the University of Minnesota Agricultural Experiment Station, Rosemount. The field, a Waukegan silt loam, had been in alfalfa the previous 3 yr. Treatments were 2 rows, 80 ft long, with 40-inch row spacing. Treatments were randomized in complete blocks with 5 replications. Granular insecticides were applied in-furrow using a planter-mounted granular applicator. For the treatment with 2 insecticides used in combination, 1 insecticide was applied with the planter empty of seed and the other was applied when planting. Every third plot was an untreated control. Once during the season, on 8 Aug, the entire experimental block was sprayed with Pydrin 2.4E, at 0.05 lb (AI)/ acre, to control potato leafhopper. Two rows were harvested from each plot 2 Oct. The potatoes were washed, counted, and scored for wireworm injury. Data for untreated control plots were pooled within replications. Control was calculated relative to the untreated plots.
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