160 likely document crape myrtle bark scale to be most important throughout the region. Sucking Insects on Leaves Primary pests in this category include phloem-feeding scales, aphids, and whiteflies. Phloem feeders dam- age trees by removing carbon and nutrients needed for growth and storage and can reduce photosynthesis and other leaf processes. In addition, phloem feeders excrete a sticky sugar-based solution called honey- dew that coats leaves, cars, sidewalks, and other sur- faces. This creates a nuisance and is often the subject of citizen complaints. For this reason, previous pest assessments often have ranked soft scales and aphids, such as elm aphids and oak aphids, in the top five pests of every region in the United States (Kielbaso and Kennedy 1983; Nielsen et al. 1985; Wu et al. 1991). Leaf suckers were the top ranked pest for Lirio- dendron spp., Lagerstroemia spp., and Platanus spp. in this survey. Tuliptree aphids (Illinoia liriodendri) can become very abundant on tulip trees where they produce copious honeydew and cause leaves to become discolored or die (Dreistadt and Dahlsten 1988). The density of honeydew drops landing below a tree can be used to monitor tuliptree aphid density as part of an IPM program (Dreistadt 1987). The most important pest of Platanus spp. is sycamore lace bug (Corythucha ciliata) a leaf sucker that causes extensive stippling on leaves which then become discolored or die. This was the only arthropod pest identified as important on Platanus spp. in this survey, though Platanus spp. are susceptible to other arthropod pests and leaf patho- gens, such as leaf scorch (Xylella fastidiosa) and plane anthracnose (Apiognomonia veneta)(Filer 1977). Leaf suckers were ranked third for Quercus spp. yet rated highly in importance (1.93). Several leaf sucking insects occur on Quercus spp., including oak lace bugs (Corythucha arcuata) and aphids (Johnson and Lyon 1976). The most prominent in the South and identified most in the survey are Parthenoleca- nium spp. Scales, including oak lecanium scale (P. quercifex), and European fruit lecanium scale (P. corni). These scales can become very abundant on willow oaks and other Quercus spp., especially under urban conditions (Meineke et al. 2013; Meineke and Frank 2018). They are univoltine throughout the South, and their life cycle includes leaf feeding and bark feeding stages (Camacho et al. 2017). This ©2019 International Society of Arboriculture Frank: Survey of Street Tree Pests identifies a weakness in the pest categories used for the survey, because some respondents listed Parthe- nolecanium spp. as bark suckers and others listed them as leaf suckers. Since Parthenolecanium spp. scales were the primary pest listed in both categories, scales likely would rank higher as pests of Quercus spp. if responses were combined in a more specific category. Defoliators and Leafminers Caterpillars are important pests of some tree species. They can defoliate susceptible species, and repeated defoliation can reduce tree growth and survival (Kul- man 1971; Coffelt et al. 1993). Even partial defolia- tion can reduce tree growth and beauty and provoke citizen complaints (Coffelt and Schultz 1990). Cater- pillar frass can be a nuisance accumulating on side- walks, decks, cars, and other surfaces, causing citizen complaints (Coffelt and Schultz 1990). Previous pest assessments have listed lepidopteran defoliators as a top pest during outbreaks of exotic pests like gypsy moth and native pests like orange-stripped oakworms and cankerworms (Nielsen et al. 1985; Wu et al. 1991; Kielbaso and Kennedy 1983). Since lepi- dopteran species often have outbreak cycles of many years, they may not be important pests every year. In this survey, lepidopteran defoliators were most important on Prunus spp. (2.27) due primarily to Prunus spp. susceptibility to eastern tent caterpillar (Malacosoma americanum), which prefer Prunus spp. such as black cherry (Prunus serotina) and can defo- liate trees. Spring cankerworm (Paleacrata vernata) and fall cankerworm (Alsophila pometaria) are gen- eralist caterpillars that feed heavily on many tree taxa including Prunus spp. Defoliators including canker- worms and more specialized caterpillars, such as orange-striped oakworm (Anisota senatoria), were the highest rated pests on Quercus spp. Orange- striped oakworms and cankerworms can defoliate large expanses of urban areas garnering citizen com- plaints, harming trees, and often leading to expensive management practices (Coffelt et al. 1993; Chan- thammavong et al. 2014; Asaro and Chamberlin 2015). Beetles eat tree leaves as larvae, adults, or both depending on species. Coleopteran defoliators, like Japanese beetles (Popillia japonica), imported wil- low leaf beetles (Plagiodera versicolora), and elm leaf beetles (Xanthogaleruca luteola), can be severe pests on certain tree species. In the 1980s, elm leaf beetle was among the highest ranked tree pest
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