CALIFORNIA DEPARTMENT OF FISH AND WILDLIFE Kuroshio and Polyphagous Shot Hole Borer in Southern California Wildlands Associated Host Identification Guide Contents Introduction ............................................................................................................................................................................ 3 Identifying Shot Hole Borer in the Field .................................................................................................................................. 4 Glossary ................................................................................................................................................................................... 5 Acacia spp. (wattles) ............................................................................................................................................................... 6 Acer negundo (box elder) ........................................................................................................................................................ 7 Acer macrophyllum (bigleaf maple) ........................................................................................................................................ 8 Aesculus californica (California buckeye) ................................................................................................................................ 9 Ailanthus altissima (tree of heaven) ..................................................................................................................................... 10 Alnus rhombifolia (white alder) ............................................................................................................................................ 11 Ambrosia monogyra (singleleaf burrobush) ......................................................................................................................... 12 Arundo donax (giant reed) .................................................................................................................................................... 13 Baccharis pilularis (coyote bush) .......................................................................................................................................... 14 Baccharis salicifolia (mulefat) ............................................................................................................................................... 15 Cercis occidentalis (western redbud) .................................................................................................................................... 16 Eucalyptus spp. (gum trees) .................................................................................................................................................. 17 Frangula californica (California coffeeberry) ........................................................................................................................ 18 Fraxinus dipetala (California ash, flowering ash) .................................................................................................................. 19 Fraxinus velutina (Arizona ash, velvet ash) ........................................................................................................................... 20 Juglans californica (California black walnut) ......................................................................................................................... 21 Lyonothamnus floribundus (Catalina ironwood) .................................................................................................................. 22 Nicotiana glauca (tree tobacco) ........................................................................................................................................... 23 Parkinsonia spp. (palo verde) ............................................................................................................................................... 24 Platanus racemosa (California sycamore) ............................................................................................................................ 25 Populus fremontii (Fremont cottonwood) ............................................................................................................................ 26 Populus trichocarpa (black cottonwood) .............................................................................................................................. 27 Prosopis spp. (mesquite) ....................................................................................................................................................... 28 Prunus ilicifolia (hollyleaf chery) ........................................................................................................................................... 29 Pyracantha spp. (firethorn)................................................................................................................................................... 30 Quercus agrifolia (coast live oak) .......................................................................................................................................... 31 Quercus chrysolepis (canyon live oak) .................................................................................................................................. 32 Quercus engelmannii (Engelmann oak) ................................................................................................................................ 33 Quercus lobata (valley white oak) ........................................................................................................................................ 34 1 Ricinus communis (castor bean) ........................................................................................................................................... 35 Robinia psuedoacacia (black locust) ..................................................................................................................................... 36 Salix exigua (narrowleaf willow, sandbar willow) ................................................................................................................. 37 Salix gooddingii (black willow) .............................................................................................................................................. 38 Salix laevigata (red willow) ................................................................................................................................................... 39 Salix lasiolepis (arroyo willow) .............................................................................................................................................. 40 Sambucus mexicana (Mexican elderberry) ........................................................................................................................... 41 Schinus terebinthifolius (Brazillian peppertree) .................................................................................................................... 42 Tamarix spp. (saltcedar, tamarisk) ........................................................................................................................................ 43 Triadica sebifera (Chinese tallow) ......................................................................................................................................... 44 Umbellularia californica (California bay-laurel, Oregon myrtle, pepperwood) .................................................................... 45 Washingtonia spp. (fan palms) ............................................................................................................................................. 46 Appendix – Key to Identifying Willows ................................................................................................................................. 47 References ............................................................................................................................................................................ 48 Compiled by Ryan Lawler and Aidan Renner, CDFW Region 5. All photos by CDFW staff unless otherwise noted. 2 Introduction Shot hole borers (SHB) and Fusarium dieback (FD) represent an increasing threat to many plant species in southern California. Two similar species of invasive shot hole borer exist in southern California, the Polyphagous shot hole borer (PSHB) and the Kuroshio shot hole borer (KSHB) (Euwallacea spp). Shot hole borers are ambrosia beetles forming a symbiotic relationship with the fungi. PSHB symbionts are Fusarium euwallaceae, Graphium euwallaceae, and Paracremonium pembeum, while KSHB forms a symbiotic relationship with two novel species of Fusarium and Graphium (Cooperband et al. 2016) (Lynch et al. 2016) (Eskalen, Stouthamer 2015). These fungi clog the host’s vascular tissue leading to branch dieback and eventually tree death. The beetles are not pathogenic in their native habitats in Southeast Asia, preferring instead to infect stressed trees (Hulcr and Dunn 2011). The two shot hole borer species found in southern California differ primarily in the fungal species they associate with but can be treated the same for the sake of management. SHB infestations begin when females burrow natal galleries into the host, introduce symbiotic fungi, and lay eggs. Females are capable of producing haploid male offspring in the absence of mating while mated females produce diploid female offspring. Eggs