Arboriculture & Urban Forestry 32(5): September 2006 249 subsequent analysis if questionable failures of efficacy were observed. Insecticides were applied with an ATV (AZ) and trailor- mounted (CA and MT) hydraulic sprayer, which allowed treatment of the entire bole of each tree, until runoff, to a height of ≈12 m (39.4 ft). This technique has been shown to result in at least 80% of the insecticide being applied to the tree bole (Haverty et al. 1983). The amount of insecticide (and water carrier) applied to each tree varied with diameter and species, the latter primarily as a result of differences in bark and crown architecture. On average, we applied 17.8 (4.7 gal), 19.5 (5.2 gal), and 3.8 L (1.0 gal) per tree for P. ponderosa, P. contorta, and P. edulis, respectively. All treat- ments were applied between 0630 and 1300 when wind speeds were <11 kph (6.8 mph). In California, insecticides were applied on 18 to 19 May 2004 to individual P. ponde- rosa (mean dbh 39.9 cm [15.7 in]) when temperatures ranged from 4.0°C (39.2°F) to 15.5°C (60°F). In Montana, insecticides were applied to individual P. contorta (mean dbh27.7 cm [10.9 in]) during 15 to 17 June 2004 when temperatures ranged from −2.0°C (28.4°F) to 10.0°C (50°F). In Arizona, insecticides were applied to individual P. edulis (mean dbh 14.8 cm [5.8 in]) during 13 to 15 April 2004 when temperatures ranged from −1.0°C (30.2°F) to 16.0°C (60.8°F). Sample trees were confirmed uninfested and located in areas with recent bark beetle activity. The spacing between adjacent trees was >100 m (328 ft) to enhance the likelihood that a sufficient number of beetles would be in the vicinity of each tree to rigorously test the efficacy of these treatments. All sample trees and the first set of untreated control trees were baited with appropriate species-specific lures (Phero Tech Inc., Delta, British Columbia, Canada) for 6 to 24 weeks (Tables 1 to 3) depending on beetle pressure in the area. The surviving treated trees in each treatment (if <7 were killed in 2004) and the second set of untreated controls (CA and MT) were rebaited in 2005. Table 1. The effectiveness of permethrin plus-C (Masterline) and carbaryl (Sevin SL) for protecting Pinus ponderosa from Dendroctonus brevicomis attack for two field seasons after treatment, Shasta County, California (40.88°N, 121.65°W), 2004 to 2005. 2004y Treatmentz Masterline Sevin SL mortality/n 2/30 0/30 Untreated control 16/30 2005x mortality/n 1/28 0/30 12/30 mg/24 h) for 42 d. xAssessed 29 October 2005. Trees actively baited for 84 d. Cumulative mortality/n 3/30 0/30 28/60 zApplied 18 to 19 May 2004. yAssessed 22 October 2004. Trees actively baited with racemic frontalin (1–3 mg/24 h), racemic exo-brevicomin (1–3 mg/24 h), and myrcene (15–20 Table 2. The effectiveness of permethrin plus-C (Masterline) and carbaryl (Sevin SL) for protecting Pinus contorta from Dendroctonus ponderosae attack for two field seasons after treatment, Beaverhead- Deerlodge National Forests, Montana (45.92°N, 121.37°W), 2004 to 2005. 2004y Treatmentz Masterline Sevin SL mortality/n 2/30 0/30 Untreated control 30/30 2005x mortality/n 14/27 1/30 22/30 Cumulative mortality/n 16/29w 1/30 52/60 zApplied 15 to 17 June 2004. yAssessed 16 to 17 September 2004. Trees actively baited with 80%-(–)- trans-verbenol (1.5 mg/24 h) and racemic exo-brevicomin (0.3 mg/24 h) for 42 d. xAssessed 27 to 28 September 2005. Trees actively baited for 42 d. wOne tree lost to wood cutting. Tree mortality was assessed in April 2005 (AZ) and Sep- tember (MT) and October (AZ and CA) 2004 to 2005. Treat- ments were considered to have sufficient beetle pressure if 60% of the untreated control trees died from bark beetle attack. Insecticide treatments were considered efficacious when <7 trees died as a result of bark beetle attack (Shea et al. 1984). These criteria were established based on a sample size of 22 to 35 trees/treatment and the test of the null hy- pothesis, Ho:S (survival 90%). These parameters provide a conservative binomial test ( 0.05) to reject Ho when more than six trees die. This experimental design is accepted as the standard for such evaluations and provides a very con- servative test of efficacy (Haverty et al. 1998). Efficacy was monitored for two field seasons after insecticide treatment. RESULTS California: D. brevicomis and P. ponderosa In 2004 and 2005, beetle pressure was insufficient to ad- equately challenge the treatments because <60% of untreated Table 3. The effectiveness of permethrin plus-C (Masterline) and carbaryl (Sevin SL) for protecting Pinus edulis from Ips confusus attack for two field seasons after treatment, Coconino County, Arizona (35.23°N, 111.51°W), 2004 to 2005. 2004y Treatmentz Masterline Sevin SL Untreated control mortality/n 1/24 0/23w 5/24 2005x mortality/n 1/23 0/23 1/19 (1–2 mg/24 h) for 168 d. xAssessed October 2005. Trees actively baited for 168 d. wOne tree lost to wood cutting. ©2006 International Society of Arboriculture Cumulative mortality/n 2/24 0/23 6/24 zApplied 13 to 15 April 2004. yAssessed April 2005. Trees actively baited with racemic ipsenol (0.1–0.3 mg/24 h), racemic ipsdienol (0.1–0.3 mg/24 h), and 83%-(–)-cis-verbenol
September 2006
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