Arboriculture & Urban Forestry 32(1): January 2006 11 Every year, approximately 10,000 to 20,000 tanglefoot bands are installed on street trees in Winnipeg to prevent cankerworm defoliation (M. Barwinsky, City of Winnipeg, pers. comm.). Despite the popularity of tree bands, there are several problems associated with their use: (1) bands can become overcrowded with dead insects, which female cankerworms may use as a “bridge” to cross the barrier and, as more insects are caught, the efficacy of the band may decrease; (2) moisture accumulates beneath the fiberglass insulation and can encourage the growth of fungi on the bark of the tree; and (3) the tanglefoot substance is very messy to apply and requires considerable clean-up (Ascerno and Hahn 2003). Otvos and Hunt (1986) showed that tanglefoot bands were very effective in the capture of winter moth (Operophtera brumata L.). The life cycle of O. brumata is similar to that of A. pometaria, and females of O. brumata are also wingless. The study compared three types of barriers: (1) a fiberglass barrier around the trunk, (2) a fiberglass barrier sprayed with Raid®, and (3) a polyethylene band coated in Tree Tanglefoot. The results of the study found that significantly fewer females passed the tanglefoot barrier in comparison to the other treatments. In addition to being highly effective, Otvos and Hunt (1986) recommended that the Tree Tanglefoot barrier be used as a control for winter moth because it was nontoxic and it eliminated the need for insecticide application. Thorpe et al. (1993), assessed the efficacy of sticky barrier bands on gypsy moth (Lymantria dispar L.) (Lepidoptera: Lymantriidae) larval density and oak tree defoliation. Adults of both sexes of L. dispar have wings, but the females cannot fly (Hiratsuka et al. 1995). Tree trunks were banded by wrapping them with duct tape and then applying Tree Tanglefoot to the center of the tape. Small gaps between the tape and the tree were filled with Tree Tanglefoot to prevent larvae from passing beneath the barrier (Thorpe et al. 1993). Thorpe et al. (1993) found that late-instar population densities in the oak canopies of banded plots were significantly lower than those of unbanded plots. Thorpe et al. (1993) also found that defolia- tion rates and the ratio of post-treatment to pretreatment egg mass density was not significantly affected by banding. They concluded that the effects of the sticky barriers on defoliation were inconsistent and that these barriers should not be relied on to protect oak foliage from gypsy moths. Despite being widely used for many decades, there exists little published information on the actual efficacy of tanglefoot bands in capturing cankerworm adults in urban forests. Envirometrics Systems, Inc. (London, Ontario) markets an alternate version of a sticky band to prevent adult females of A. pometaria and P. vernata from reaching the canopy to lay eggs. The Bug Barrier Tree Band™ consists of a layer of synthetic foam placed around the trunk over which a plastic shield is placed, which rests several centimeters away from the bark. The underside of this plastic shield is coated with an adhesive film on which insects become trapped. The product is also meant to be effective against gypsy moth, forest tent caterpillar, and ants (Envirometrics Systems 2005). Envirometrics Systems has designed the band to be unaffected by falling debris such as leaves, twigs, and bark and to require little maintenance (Envirometrics Systems 2002). The company notes that the product is easily installed and removed, without the mess and stickiness encountered when using traditional sticky bands (Envirometrics Systems 2005). The purpose of this study was to compare the effective- ness of tanglefoot bands and the Bug Barrier Tree Band in preventing the upward movement of female cankerworms on the trunk and to examine cankerworm preference for tree species. The efficacy of the bands was determined by measuring the defoliation caused by cankerworm larvae, the number of larvae per branch sample, and by observing the number of female moths that crossed over the test bands. MATERIALS AND METHODS Experiment 1 Experiment 1 (fall 2002) was replicated at two sites, St. John’s Cemetery and along Lyndale Drive in Winnipeg, Manitoba (49° 53' N, 97° 09' W). Sites were approximately 5 km (3 mi) apart and were chosen because they had a history of cankerworm defoliation. Host trees included green ash (Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern.), American elm (Ulmus americana L.), and Siberian elm (Ulmus pumila L. ). St. John’s Cemetery is surrounded by a large residential community and bordered by the Red River on the eastern edge approximately 200 m (219 yd) away. Lyndale Drive is a park bordered on the southwest side by the Red River and northeast side by a residential community. All treatment trees were in close proximity to each other but were far enough apart to prevent larvae from moving between trees via silken threads. Treatment trees were estimated to be at least 4 m (13 ft) in height and were identified as being healthy at the beginning of the experi- ment (no infections of Dutch elm disease were apparent in elm trees). Diameter at breast height (dbh) was recorded for each tree using a standard dbh tape. Two treatments were established at each site. Treatment 1 consisted of a Bug Barrier Tree Band placed approximately 1.3 m (4.3 ft) high on the trunk (Figure 1), and treatment 2 consisted of a tanglefoot band placed at 1.3 m (4.3 ft) high on the trunk (Figure 2). Treatments were randomly assigned and repli- cated eight times at Lyndale Drive and five times at St. John’s Cemetery. Bands were placed on trees prior to adult emergence in September 2002 and removed after the first significant snowfall in November 2002. They were wrapped in plastic bags for transport and the number of A. pometaria adults captured was determined in the laboratory. ©2006 International Society of Arboriculture
January 2006
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