238 to R. Anderson (Canadian Museum of Nature, Ottawa, Ontario, Canada) who identified them as Oedophrys hilleri (Coleoptera: Curculionidae), a new state record for Kentucky. Adults feed on leaves of peach, apple, and other rosaceous plants (Brown and Matthews 2009) but have not previously been reported dam- aging elm trees. Adult populations were sampled of adults on each tree were sampled on July 11–12 and August 11 in 2011, and on August 8, 2012. The first sampling was with a gasoline- powered leaf blower reversed for suction and fitted with a paint strainer in the intake tube. Each tree’s canopy was sampled for 60 seconds; samples then were transferred to bags and frozen before counting. For subsequent samples, researchers used a beating sheet (71 cm × 71 cm, BioQuip, Rancho Dominguez, California, U.S.), striking eight branches (four each in lower and upper canopy) with a stick and counting dislodged weevils. Two species of foliage-distorting woolly aphids (Figure 1) were abundant enough to evaluate in 2012. Spring feeding by woolly elm aphid, Eriosoma americanum (Hemiptera: Aphididae), causes developing leaves to swell and their edges to curl down- ward. The aphids feed and reproduce within the leaf rolls. Spring feeding by woolly apple aphid, Eriosoma lanigerum (Hemiptera: Aphididae), results in unsightly rosette-like clusters of deformed leaves at the ends of shoots (Figure 1). Both aphids also cause damage by sucking sap from the host, and by produc- ing honeydew. Incidence of each pest’s damage was assessed in early June by two observers who counted all individually-rolled leaves (E. americanum) and rosettes (E. lanigerum) on each tree. Elm cockscomb gall aphid, Colopha ulmicola (Hemiptera: Aphididae), is a relatively minor pest that induces elongated, raised, irregularly-toothed galls on the adaxial surface of leaves. The gall’s shape and reddish color at maturity account for the common name. The leaf galls harden and turn brown after the aphids depart. The number of galls on each tree (to 2.5 m height) were counted by two observers on July 11–12, 2011, and on June 7–8, 2012. Statistical analyses and resistance ratings Numbers of each pest were compared among cultivars by two- way analysis of variance (ANOVA) and pre-planned single degree of freedom linear contrasts between groups of elm species or parentages. Log or square root transformations were used if needed to meet assumptions of normality and homo- geneity of variance. The nonparametric Kruskal-Wallis test was used in cases where ANOVA assumptions could not be met because of all zeroes for some cultivars. Statistix version 9.0 (Analytical Software 2008) was used for analyses. All data are reported as original means ± Standard Error (SE). Cultivar means for pests previously monitored (Condra et al. 2010) were averaged across the 2–3 growing seasons each was evaluated and then ranked on a 1–5 scale based on pest density or extent of damage. The most susceptible cultivar(s) always received a 5 rating, and cultivars that sustained no damage or infestation by a particular insect received a 0 rating for that pest. For Japanese beetle defoliation, 0–5 ratings corresponded to <10, 22–20, 21–30, 31–40, 41–55, and >55% cumulative leaf loss, respectively. Tree ratings for the leafminers O. alni, A. aristata, and K. ulmi, and for T. nigriabdominalis aphid pod galls were based on numbers of mines or galled leaves per 100 leaves (2006–2008) or per ten 30-cm shoots (2009–2012), with 1–5 ratings generally assigned to cultivars ranked in successive quintiles of the fre- quency distribution. For those pests first reported on in this paper, ©2013 International Society of Arboriculture Potter and Redmond: Elm Resistance to Insect Pests Figure. 1. Insect pests and damage symptoms evaluated in the Kentucky portion of the National Elm Trial from 2010–2012: (A) European fruit lecanium (Parthenolecanium corni), (B) European elm scale (Eriococcus spuria), (C) cottony maple scale (Pulvinaria innumerabilis), (D) woolly elm aphid (Eriosoma americanum), (E) woolly apple aphid (Eriosoma lanigerum), (F) elm cockscomb gall aphid (Colopha ulmicola), (G) Oedophrys hilleri weevil (photo by S. Cresswell), (H) leaf notching by O. hilleri. See Condra et al. (2010) for images of previously evaluated pests. cultivar ratings were based on number of European fruit lecanium and European elm scale per 1.5 m of twig length, or whole tree counts for O. hilleri, elm cockscomb gall aphid, wooly elm aphid, wooly apple aphid, and cottony maple scale, as described herein. For susceptibility/resistance rankings, the study authors con- sidered four of the insect species, Japanese beetle, European elm flea weevil, European fruit lecanium, and European elm scale, as “major” pests because, at least in Kentucky, their impact on heavily- infested trees and/or problems associated with their honeydew can be serious enough to warrant control. Ratings for those four pests were doubled and then added to the sum of ratings for the remaining eight pests to get overall scores upon which the 20 elm genotypes were ranked for relative susceptibility to insect pests. RESULTS European fruit lecanium and European elm scale were the most abundant scale insects infesting elms at the study site. The former was found almost exclusively on twigs, whereas the latter
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