(L4) BLUEBERRY: Vaccinium angustifolium Aiton, 'Lowbush' J. A. Collins Dept. of Biological Sciences 5722 Deering Hall University of Maine Orono, ME 04469 Phone: (207) 581-2868 Fax: (207) 581-2969 E-mail: Judith.Collins@umit.maine.edu F. A. Drummond Dept. of Biological Sciences 5722 Deering Hall University of Maine Orono, ME 04469 Phone: (207) 581-2989 Fax: (207) 581-2969 E-mail: Frank.Drummond@umit.maine.edu Blueberry spanworm (SW): Itame argillacearia (Parkard) Each treatment was applied on 21 Jun in 25 gpa with a CO -propelled, 80-inch boom sprayer (76-inch swath) equipped with four, flat-spray 8002VS TeeJet nozzles operating at 35 psi and at a slow walking speed. Speed was regulated using a metronome. The materials were allowed to dry on the foliage. Field-collected, mid- to late instar SW larvae were placed in plastic cups with petri dish lids. There were three replications of five SW each (three replications of four SW each in the untreated check, and one replication of five SW and two replications of four SW for Assail). One treated stem was cut and placed in each cup. The cups were held in a growth chamber at approximately 21°C and assessed for mortality at daily intervals for five days. Untreated blueberry foliage was added to each cup as needed. The Product-Limit Survival (Kaplan-Meier) Method and Gehan-Wilcoxon Mean Separation were used to compare the mean days to death of each treatment to the untreated check. Logistic Regression was used to compare percent survival among the treatments. All four materials were significantly different from the check (Table 1). As expected, mean days to death following application of the insect growth regulator Intrepid 2 F was longer then with the other materials, but still significantly less then the untreated check. Table 2 shows percent survival of larvae treated with each material. All four materials provided excellent control. On day 4, 66.7% of larvae fed Intrepid-treated foliage were alive compared to 8.3, 0.0, and 13.3% of larvae fed foliage treated with Assail, Entrust, and Avaunt, respectively. Percent survival on day 5 was only 6.7% vs. 0.0% in the other treatments; 91.7% of the untreated check larvae remained alive at the conclusion of the trial. Table 1. Treatment/ Rate amt Mean a 2 c formulation product/acre days to death Prob X ≤ 0.05 Assail 30SG 5.3 oz 1.00 < 0.0001 Avaunt 30WG 6.0 oz 2.00 < 0.0001 Entrust 80WP 2.0 oz 1.00 < 0.0001 Intrepid 2F 16.0 fl oz 5.00 < 0.0001 Untreated check -- -- NA Biased estimate due to censored observations (live larvae) at end of study. Not possible to estimate because of > 50% survival. Pair-wise comparison with untreated check.. Table 2. Percent survival on day after application Treatment/ Rate amt formulation product/acre 1 2 3 4 5 Assail 30SG 5.3 oz 41.7b 16.7bc 16.7bc 8.3b 0.0c Avaunt 30WG 6.0 oz 80.0a 33.3b 26.7b 13.3b 0.0c Entrust 80WP 2.0 oz 6.7c 6.7c 0.0c 0.0b 0.0c Intrepid 2F 16.0 oz 100.0a 100.0a 80.0a 66.7a 6.7b Untreated check -- 100.0a 100.0a 100.0a 91.7a 91.7a Mean percent survival within each sample day, followed by the same letter(s), are not significantly different (Logistic Regression).
Arthropod Management Tests – Oxford University Press
Published: Jan 1, 2006