Journal of Arboriculture 31(4): July 2005 199 4.3 to 5.5 m (14.2 to 18.2 ft), and branches were not interconnected. Treatments included label rates (listed in Table 1) of acephate (Orthene TT&O 97® , Valent USA Corp., Walnut Creek, CA), bifenthrin (Talstar Flowable® FMC, Philadelphia, PA), imidacloprid (Merit 75 WP® Environmental Science, Montvale, NJ), horticultural oil (Sunspray Ultra-Fine® , , Bayer , Philadelphia, PA), horticultural oil plus acephate, and an untreated control. Adjuvant was not mixed with the insecticides. An ISA Certified Arborist applied the insecticides on 1 and 2 May 2003. Acephate, bifenthrin, horticultural oil, and horticultural oil + acephate were applied as foliar sprays using a hydraulic sprayer (pressure: 25 mL/m2 [1 oz/ft2 ]) with a 756 L (200 gal) agitating tank and a single, handheld sprayer. Trees were sprayed until runoff. For a soil drench, imidacloprid was sprayed with an 18.9 L (5 gal) Solo backpack sprayer within a tree’s drip line, until the soil was evenly saturated. Equip- ment was triple-rinsed between treatments. Air temperature, relative humidity, wind speed, and cloud conditions were noted at application. Treatment efficacy was evaluated by collecting four branches from each tree and counting the total number of live and dead first and second instar A. kingii. One branch (20 to 26 cm [8 to 10 in.] long) was randomly cut from each of the four cardinal points of each tree, approximately 1.8 to 3.7 m (5.9 to 12.2 ft) up from the ground on 24 April (pretreatment), 9 May (1 week after treatment, WAT), 22 May (3 WAT), 5 June (5 WAT), and 19 June (7 WAT) 2003. The branches were frozen, and scales were later examined with a dissecting binocular microscope. First and early second instars that survived the treatments were salmon- colored. However, insecticide-killed nymphs were slightly brown and shriveled. A waxy secretion normally coats the derm of healthy second instars, but those affected by insecticides had black spots on the wax layer. Statistical Analysis The mean number of healthy first and second instar A. kingii per four-branch sample was calculated using a one-way analysis of variance (ANOVA) (P < 0.05), and treatments were compared to the control using a Dunnett’s test on each date (JMP®, SAS Institute 2001). The proportion of scale mortality was calculated by dividing the total number of dead nymphs by the total number of live and dead nymphs for each branch on each date. Proportions were arc-sine square root- transformed, analyzed with RESULTS Study Site This study was conducted on Q. geminata and Q. virginiana, which represent new host records for A. kingii. Tree height on 10 May 2002 was 5.9 ± 0.7 m (19.5 ± 2.3 ft), dbh was 51.7 ± 14.3 cm (20.4 ± 5.6 in.), and the crown diameter was 9.4 ± 1.3 m (31.0 ± 4.3 ft). Tree height on 29 August 2003 was 6.4 ± 1.0 m (21.1 ± 3.3 ft), dbh was 52.4 ± 14.8 cm (20.6 ± 5.8 in.), and crown diameter was 10.3 ± 2.2 m (34.0 ± 7.3 ft). From 6 June 2002 to 29 August 2003, we found 728.6 ± 399.1 (range, 166 to 1,755) A. kingii, all life stages combined, on 1,120 main branches (22.9 ± 2.3 cm [9.0 ± 0.9 in.]) and 781.6 ± 309.2 A. kingii (range, 371 to 1,586) on lateral shoots (4.2 ± 1.0 cm [1.7 ± 0.4 in.]). The scale’s life cycle did not appear to vary depending on the host tree species. Life Cycle Allokermes kingii has two generations each year in Clearwater, Florida (Figure 1). Salmon-colored crawlers emerged from late May to the first week of August in 2002. Females migrated to the larger branches, while males went onto the tree stem. Crawlers began to molt into second instars by mid-July. At this time, second instar females migrated to tree wounds or new growth, often near new leaf petioles, became sessile, and secreted a hard, waxy covering over themselves. Females molted into adults from late August to mid-December. A third instar was not observed in females in this study. Eggs were laid in female brood chambers and were present from early September to mid-December. Second-generation crawlers began emerging in mid- September and some molted into second instars by mid- October. First and second instar nymphs overwintered on the trees. By late April to early May, female A. kingii molted into mature adults. Second-generation adult female A. kingii produced eggs until mid-June. an ANOVA, and, if statistically significant, treatments were compared to the control using a Dunnett’s test on each date (JMP® , SAS Institute 2001). Figure 1. Seasonal life history of Allokermes kingii in Clearwater, Florida. ©2005 International Society of Arboriculture
July 2005
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