102 in 2003. Prior to 2007, EEFW had been documented only in the Illinois and Wisconsin states (Anderson et al. 2007). An- other leafminer, Agromyza aristata, was also abundant. As there is little published information on the biology of either species, their seasonal life histories in Kentucky are also reported here. Condra et al.: Elm Resistance to Insect Pests 50 m between replicates. Seventeen cultivars were planted in spring 2005; three others were planted in randomized spaces left in each block in spring 2006 or 2007. The trees were obtained from nurs- eries as bare-root transplants and ranged from 1.5–2.4 m height at time of planting. They were staked, watered as needed, and mulched over grass that had been killed with glyphosate herbicide. Many of the cultivars have dissimilar leaf size, so 20 fully expanded leaves were collected from each tree in early June 2009 and measured with an electronic area meter (Li-Cor, Lincoln, NE) so that certain parameters (e.g., EEFW adult feeding injury) could be compared on a per-area basis. Leaf pubescence was characterized by examining lower (abax- ial) and upper (adaxial) leaf surfaces of leaves from each tree with a binocular microscope. Trichome density was subjec- tively rated as 0, 1, 2, 3, or 4 corresponding to glabrous (few or none), light, moderate, dense, or very dense, respectively. Figure 1. Leaf mines and aphid pouch galls evaluated on trees in the National Elm Trial site in Lexington, Kentucky: (a) serpentine- blotch mine of Orchestes alni; (b) serpentine mine of Agromyza aristata, (c) Blotch mine of Kaliofenusa ulmi, (d) gall induced by Tetraneura nigriabdominalis. Figure 2. Life stages and symptoms of European elm flea wee- vil, Orchestes alni: (a) adult weevil, (b) larva removed from mine, (c, d) adult feeding injury. A typical mine is shown in Figure 1. METHODS AND MATERIALS The main study site was an open, grassy area on Maury silt loam soil on the University of Kentucky campus in Lexington, Kentucky, adjacent to the Arboretum and State Botanical Garden of Kentucky (N38°1’; W84°30’; elevation 302 m). Five replicates of 20 elm cul- tivars, including North American, Asian, and European species and hybrids (Table 1), were planted in a randomized complete block in rows spaced 7.6 m apart, with 7.6 m between trees within rows and ©2010 International Society of Arboriculture Pest Resistance Evaluations Density of leaf galls and leaf mines was assessed by two individu- als on all trees in May 2006, 2008, and 2009. Sampling in 2006 and 2008 was performed by blindly selecting 10 or more shoots from all sides of the lower two-thirds of each tree and inspecting ≤ 10 leaves per shoot (100 total leaves per tree). Sampling was slightly modified in 2009 when all leaves and pests on the terminal 30 cm of the new growth of 10 blindly-selected shoots per tree were counted. Numbers of mines or galls per infested leaf also were re- corded. Mines were characterized by their distinctive shapes (ser- pentine, linear blotch, or blotch), until rearing had confirmed iden- tity of their causal species. Six consecutive days with subfreezing temperatures (April 5–10, 2007; lows of -1.1, -3.9, -5.6, -5.6, -3.9, and -1.7°C, respectively), damaged young leaves of early- flushing cultivars, preventing comparisons of leaf miner and gall densities in that year. The trees however, re-foliated within a few weeks allowing the study authors to evaluate JB damage in 2007. Representative leaf galls were dissected and the aphids within them were sent to S. Halbert for identification (Florida State Col- lection of Arthropods, Gainesville, FL). Voucher specimens were deposited in the Florida State Collection of Arthropods (FSCA# E2008-4088). Approximately 200 mined leaves with late-instar larvae or pupae were held in the lab in translucent plastic con- tainers with moist florist’s foam to rear adults for identification. One of the two predominant species, Agromyza aristata Malloch (= A. ulmi), was identified via keys and descriptions (Needham et al. 1928; Spencer 1973). Adults of other abundant species, a leaf-mining weevil, were sent to R. Anderson (Canadian Museum of Natural History) who identified them as EEFW, which had not previously been reported in Kentucky. Voucher specimens are de- posited in the University of Kentucky Insect Collection. Whole- tree leaf area loss from skeletonization by Japanese beetles was visually estimated (nearest 10%) by two independent observ- ers just after peak flight each summer in late July 2006–2008. The two ratings were averaged to provide a single estimate for each tree which was used in the statistical analyses. Area-wide Japanese beetle populations were unusually low in 2009, as such, whole-tree defoliation ratings were not done in that year. Relative resistance to Japanese beetles was generally consistent for particular cultivars from year to year except for the U. ameri- cana cultivar ‘Prairie Expedition’ which sustained disproportion- ately high injury in 2007, the year it was planted. To determine if
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