248 rates listed in Table 1, chlorantraniliprole at half rate (12.13 ml/m), and untreated checks. The in- secticides were applied via basal drench (1 L per shrub) on 23 October 2015. The plants were not subsequently irrigated, but there was 11.9 cm of rainfall from 23 October to 1 December 2015, which was 1.3 cm above normal for that period. Roseslug sawfly damage was evaluated 03 May 2016 by two observers who independently counted all current-year leaves on each shrub with that pest’s characteristic window-feeding and skeletonization. On 28 June, twigs bear- ing five intact leaflets each were harvested from each plant, placed in 0.24 L transparent dishes, and challenged with five field-collected JB females that had been starved overnight. The JB were allowed to feed for 24 hours, remaining leaf material was scanned to determine amount eaten (cm2 ), and beetle vigor was assessed with a fly-off assay. Methods were as described earlier for evaluating foliar sprays for JB on linden. RESULTS Control Japanese beetles and feeding damage on linden Field-weathered dry residues of chlorantra- niliprole gave nearly complete suppression of JB feeding for at least 28 days, longer than either standard in the 2011 trial (Figure 1A). Carbaryl began losing activity after 7–14 days, whereas bifenthrin was as effective as chlorantraniliprole after 14 days, but slightly less so after 28 days (Figure 1A). Data for 7- and 21-day-old resi- dues of the respective insecticides (not shown) showed a similar pattern. Chlorantraniliprole also gave as good or better “knockdown” of JB than did the standards. Mean numbers of beetles (out of 5) capable of flight after feeding for 24 hours on leaves with 1-day-old dry residues on chlorantraniliprole, bifenthrin, or carbaryl (label rates) were 0.6 ± 0.2, 0.9 ± 0.05, and 0, respec- tively, compared to 5.0 ± 0.0 for cohorts feed- ing on the untreated leaves (F3,19 = 64.0, P < 0.001). Numbers of flight-capable beetles (out of 5) were 0.4 ± 0.4, 4.0 ± 0.3, 3.1 ± 0.6, and 3.8 ± 0.5, for cohorts provided leaves with 14-day- old residues of chlorantraniliprole, bifenthrin, ©2017 International Society of Arboriculture Redmond and Potter: Acelepryn Control of Horticultural Pests or carbaryl, or untreated foliage, respectively niliprole again gave longer-lasting suppression than did either standard (Figure 1B). Reduced rates of chlorantraniliprole were as effective as the full label rate of bifenthrin (Figure 1C). (F3,19 = 18.6, P < 0.001). In 2012, chlorantra- Figure 1. Three trials comparing field-weathered residues of chlorantraniliprole and insecticide standards for reducing Japanese beetle feeding on linden foliage. A) Trial 1 (2011): F3,2 107.6, and 36.9 for 7-, 14-, and 21-day-old residues, respec- tively; P < 0.001; C) Trial 3 (2012, reduced rates of chloran- traniliprole, 7-day-old residues): F4,28 = 21.6; P < 0.001. Within trial and residue age, means not topped by the same letter are significantly different (LSD; P < 0.05). Evergreen bagworm on arborvitae Early instar bagworms feeding on arborvitae foliage with chlorantraniliprole or B. thuringi- ensis residues suffered 100% and 80% mortal- ity, respectively, within 48 hours (Figure 2A). Although the proportion of early instars killed (out of 40) did not differ between those treatments (Fisher’s exact test, P = 0.52), chlorantraniliprole 1 = 96.9, 43.3, and 126.9 for 1-, 14-, and 28-day-old resi- dues, respectively; P < 0.001; B) Trial 2 (2012): F3,21 = 50.5,
November 2017
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