Prunus Prunus Prunus Is a Large Genus of Over 400 Species and Hybrids in the Rose Family Which Includes Apri Cots, Nectarines, Peaches, Cherries, Plums and Almonds

Home , Damson, Dibotryon morbosum, Prunus domestica, Prunus sargentii, Prunus takesimensis

nysipm.cornell.edu 2019 Search for this title at the NYSIPM Publications collection: ecommons.cornell.edu/handle/1813/41246 Disease and Insect Resistant Ornamental Plants Mary Thurn, Elizabeth Lamb, and Brian Eshenaur New York State Integrated Pest Management Program, Cornell University

Prunus Prunus Prunus is a large genus of over 400 species and hybrids in the rose family which includes apri cots, nectarines, peaches, cherries, plums and almonds. Stone fruit trees are important agri cultural crops, but many are also grown for their ornamental value. Flowering cherries are prized for their showy spring blooms, fall foliage and attractive bark. The historic Tidal Basin cherry trees in Wash ington, DC are perhaps the most famous display of this popular landscape plant in the US. Flow ering plums, particularly purple-leaved cultivars, are also widely grown. Like other members of the rose family, Prunus has many potential disease and insect prob lems and some types may be short-lived in the landscape. DISEASES Bacterial Canker caused by Pseudomonas syringae pv. syringae affects many plants, including ornamental cherries and plums. It is a common problem in parts of the Pacific Northwest where cool, wet spring weather is prevalent (15). On Prunus, the disease causes blossom blight, necrotic spots on leaves and fruit, and branch cankers. Prunus sargentii ‘Rancho' and P. x yedoensis ‘Akebono' appear to have some resistance (16).

Black Knot is a fungal disease caused by Apiosporina morbosa (syn. Dibotryon morbosum) that affects both wild and cultivated species in the genus Prunus, especially plums and cherries. Infected branches develop unsightly elongated swellings or galls that can girdle branches, causing decline and dieback. As the disease progresses, trees lose vigor and may eventually die. In early stages, this disease can be managed by pruning to remove affected branches. Host species are numerous and include P. americana, P. avium, P. cerasifera, P. cerasus, P. domestica, P. mahaleb, P. nigra, P. padus, P. pensylvanica, P. salicina, P. serotina, P. virginiana (21), and P. cerasifera ‘Thundercloud' (5). A range of susceptibility has been reported for cultivars of edible or domestic plums. Black Knot Reference Species/Hybrids Cultivar Resistant Intermediate Susceptible Prunus domestica Bluebyrd 19 Bluefre 19 Damson 19, 25 Early Italian 19 (Early Fellenberg) Formosa 25 HoneySweet 19 Italian (Fellenberg) Lombard 19 Orablue 19 President 19, 22, 25 Santa Rosa 25 Shiro 25 Shropshire 19, 22 Stanley 19, 22 Veeblue 19 Prunus x Bruce 11 Crimson 11 Methley 11 Munson 11 Ozark Premier 11

Brown Rot caused by Monilinia spp. is a fungal disease of stone fruits which causes blossom and shoot blight, twig cankers, and fruit rot. Common hosts are P. avium, P. cerasus, P. domestica, P. glandulosa, P. triloba, P. serotina, and P. virginiana (2, 21). Some resistance is reported for P. sargentii ‘Columnar', P. serrulata ‘Mt. Fuji', and P. x yedoensis ‘Akebono' (16). Researchers in the Czech Republic evaluated 69 domestic plum cultivars for resistance to blight caused by M. laxa. ‘Bluefre', ‘Empress', ‘Tipala', ‘Topstar', and ‘Vanier' were highly susceptible. Resistant cultivars included ‘Colora', ‘Common Prune', ‘Jubileum', ‘Kometa', ‘Najdona', and ‘Zurna' (9).

Cherry Leaf Spot, caused by the fungal pathogen Blumeriella jaapii, is a major disease of Prunus in all humid cherry-growing regions of the world (23). There are many hosts of cherry leaf spot in cluding ornamental cherries, sweet cherries (P. avium), black cherries (P. serotina), and especially sour cherries (P. cerasus) (6). Symptoms include reddish-purple spots on upper sides of leaves which may develop into “shot holes”, leaf chlorosis, decreased fruit quality, and premature defoliation. The wild Prunus species P. canescens has been identified as a source of cherry leaf spot resistance (23). Researchers at Michigan State University's sour cherry breeding program report P. canescens-derived resistance increases the potential for successful breeding of resistant cultivars (1). Researchers at Tennessee State University evaluated six commercially available ornamental cherry cultivars for host resistance. Cherry Leaf Spot Species/Hybrids Cultivar Rating* Reference Prunus serrulata Kwanzan MR 10 Prunus subhirtella Autumnalis MS 10 Prunus x yedoensis Akebono MS 10 Yoshino S 10 Prunus x Okame MS 10 Snowgoose MS 10 *R=resistant, MR=moderately resistant, MS=moderately susceptible, S=susceptible

Plum Pox is a disease of stone fruits caused by multiple strains of plum pox virus (PPV). Known as sharka disease in Europe where it was first observed on Bulgarian plums in 1910, it reduces fruit yield and quality, causing leaf mottling, fruit malformation, fruit drop and dieback (21). Plum pox was first reported in the US in Pennsylvania in 1999, New York and Michigan in 2006, and in Canada in 2000. It can infect all cultivated stone fruit species, as well as wild and ornamental Prunus (4). Most cultivars of P. domestica are susceptible (14). European plum breeding programs have developed P. domestica cultivars with resistance to PPV. The Fruit Growing Institute of Bulgaria reports ‘Ostromila', ‘Ulpia' and ‘Sineva' are tolerant (26, 27). Re searchers in the Czech Republic observed partial resistance in ‘Jojo' (14), and researchers in Poland have released a tolerant cultivar, ‘Kalipso' (24). A team of US and French scientists developed ‘HoneySweet', the first genetically engineered PPV-resistant cultivar (20). The USDA deregulated this cultivar in 2007 providing a source of germplasm for plum breeding programs. For more information on PPV in the US, visit the USDA APHIS website: aphis.usda.gov/aphis/ourfocus/planthealth/plant-pest-and-disease-programs/pests-and-diseases/ plum-pox/ct plum pox Root Rot, caused by various soil-borne Phytophthora spp., is a water mold disease that affects many ornamentals, particularly in sites with poor drainage. Favored by high soil moisture and warm soil temperatures, the disease kills roots which disrupts movement of water and nutrients eventually re sulting in wilt and death of the plant. Water and site management are key to prevention-avoid heavy, poorly drained soils and overwatering. Symptoms caused by root damage vary depending on host plant and pathogen and may include leaf and shoot dieback, stem cankers and death of roots (21). Researchers at the US National Arboretum assessed susceptibility of eight Prunus spp. used in the ornamental shrub breeding program to a combination of flooding and Phytophthora soil infestations. Prunus takesimensis ‘Nakai', P. mahaleb, and P. yedoensis showed some tolerance to flooding and the pathogen. Prunus sargentii appeared to be least tolerant of the pathogen (7). INSECTS Gypsy Moth, Lymantria dispar, was introduced to the US from Europe in 1870 near Boston. With no natural enemies to slow its spread, this invasive species is one of the most destructive forest pests in the Northeast and has been found with increasing frequency in many other states and parts of Canada. Among hardwoods, oaks are the primary host, but many other species may also be attacked (8). A study on the susceptibility of selected landscape trees to gypsy moth defoliation in Michigan found heavy defoliation (30-70%) on P. cerasifera ‘Thundercloud' and less than 4% on P. serrulata ‘Kwanzan' (13).

Spotted Lanternfly, Lycorma delicatula, is an invasive insect pest native to China, Vietnam and India. First discovered in the US in Pennsylvania in 2014, it has since been found in Delaware, Mary land, Virginia, New Jersey, and New York. Preferred hosts for adults are Ailanthus altissima, Tree of Heaven, and Vitis vinifera, grapevine. Nymphs feed on many hosts, including stone fruits in the genus Prunus. For more information on this potential threat to many plant species, visit NYS IPM's Invasive Species website at: nysipm.cornell.edu/environment/invasive-species-exotic-pests/spotted-lanternfly/ Japanese Beetle, Popillia japonica, is a common foliage feeder of woody ornamentals including many Prunus species. Flowering cherry is a common host (8).

Japanese Beetle Reference Species/Hybrids Cultivar Resistant Susceptible Prunus avium 3 Prunus bessyi 12 Prunus cerasifera Frankthrees 18 Newport 18 Thundercloud 18 Prunus cerasus 3 Prunus domestica 3 Prunus laurocerasus 12 Prunus mahaleb 12 Prunus padus 12 Prunus salicina 3 Prunus sargentii 17 Prunus serrulata 3 Prunus serrulata Kwanzan 17 Mt. Fuji 17 Tai Haku 17 Prunus serotina 3 Prunus subhirtella Autumnalis Rosea 17 Prunus virginiana 3 Prunus virginiana Canada Red 12, 18 Prunus x blireiana 18 Prunus x cistena 18 Prunus x incamp Okame 17 Prunus x yedoensis 10 Prunus x yedoensis Afterglow 17 Akebono 17 REFERENCES 1. Anderson, K.L., A.M. Sebolt, G.W. Sundin, and A.F. Iezzoni. 2017. Assessment of the inheritance of resistance and tolerance in cherry (Prunus sp.) to Blumeriella jaapii, the causal agent of cherry leaf spot. Plant Pathology Vol. 538. doi: 10.1111/ppa.12765 2. Farr, D.F. G.F. Bills, G.P. Chamuris, and A.Y. Rossman. 1989. Fungi on Plants and Plant Products in the United States. APS Press, St. Paul, MN. 3. Fleming, W.E. 1972. Biology of the Japanese beetle. Technical Bulletin 1449 of the Agricultural Research Service, USDA, Washington, DC. 4. Fuchs, M., R. Cox, and K. Cox. 2008. Plum Pox Disease of Stone Fruits. Cornell University, New York State IPM Program, Tree Fruit Fact Sheet. hdl.handle.net/1813/43119 5. Fulcher, A., and J. Hartman. 2003. Black knot incidence on two species of Prunus in Kentucky nurseries. Proc. Southern Nurs. Assoc. Res. Conf. 48:237-239. 6. Guo, Y., M. Kramer, and M. Pooler. 2018. Screening ornamental cherry (Prunus) taxa for resistance to infection by Blumeriella jaapii. HortScience 53(2):200-203. doi: 10.21273/ HORTSCI12563-17 7. Jacobs, K.A., and G.R. Johnson. 1996. Ornamental cherry tolerance of flooding and phytophthora root rot. HortScience, 31(6):988-991. 8. Johnson, W.T., and H.H. Lyon. 1991. Insects that Feed on Trees and Shrubs. 2nd Ed. Cornell Univ. Press, Ithaca, NY. 9. Jonas, M., R. Vavra, and J. Blazek. 2017. Occurrence of blossom and twig blight caused by Moni- linia laxa on plum cultivars. Acta Hortic. 1172:35-39, ISHS. doi: 10.17660/ActaHortic.2017.1172.6 10. Joshua, J., M.T. Mmbaga, and L.A. Mackasmiel. 2017. Cherry leaf spot disease management in ornamental cherries in mid-Tennessee. Can. J. Plant Sci. 97:110-118. doi: 10.1139/cjps-2015-0362 11. Norton, J.D., and G.E. Boyhan. 1991. Inheritance of resistance to black knot in plums. HortScience 26(12):1540. 12. Patton, C.A., T.G. Ranney, J.D. Burton, and J.F. Walgenbach. 1997. Natural pest resistance of Prunus taxa to feeding by adult Japanese beetles: Role of endogenous allelochemicals in host plant resistance. J. Amer. Soc. Hort. Sci. 122(5):668-672. 13. Peterson, N.C., and D.R. Smitley. 1991. Susceptibility of selected shade and flowering trees to gypsy moth (Lepidoptera: Lymantriidae). J. Econ. Entomol. 84(2):587-592. doi: 10.1093/jee/84.2.587 14. Polak, J., J. Pivalova, and J. Svoboda. 2005. Prune cv. Jojo resistance to different strains of plum pox virus. Plant Prot. Sci. 41(2):47-51. doi: 10.17221/2742-PPS 15. Pscheidt, J.W., and R.S. Byther. 2001. Prunus Diseases, pp. 317-325. In: R.K. Jones and D.M. Benson, editors. Diseases of Woody Ornamentals and Trees in Nurseries. APS Press, St. Paul, MN. 16. Pscheidt, J.W., and C.M. Ocamb (Senior Eds.). 2018 Pacific Northwest Disease Management Handbook. ©Oregon State University. 17. Ranney, T.G., and J.F. Walgenbach. 1992. Feeding preference of Japanese beetles for taxa of birch, cherry and crabapple. J. Environ. Hort. 10(3):177-180. 18. Rowe, W.J., II, D.A. Potter, and R.E. McNiel. 2002. Susceptibility of purple- versus green-leaved cultivars of woody landscape plants to the Japanese beetle. HortScience, 37(2):362-366. 19. Scorza, R., and M. Demuth. 2015. Black knot [Apiosporina morbosa (Schw.)] resistance in import ed and domestic Prunus domestica L. germplasm and cultivars. J. Amer. Pomol. Soc. 69(1):45-50. 20. Scorza, R., M. Ravelonandro, A. Callahan, I. Zagrai, et al. 2016. ‘HoneySweet' (C5), the first ge netically engineered plum pox virus-resistant plum (Prunus domestica L.) cultivar. HortScience 51(5):601-603. 21. Sinclair, W., and H.H. Lyon. 2005. Diseases of Trees and Shrubs. 2nd Ed. Cornell Univ. Press, Ithaca, NY. 22. Smith, D. 1966. A study of certain aspects of the black knot disease of plum and its causal agent, Dibotryon morbosum (Schw.) Theiss. and Syd. PhD Diss., Pennsylvania State Univ., University Park. (Diss. Abstr. 67-1956). 23. Stegmeir, R., M. Schuster, A. Sebolt, U. Rosyara, G.W. Sundin, and A. Iezzoni. 2014. Cherry leaf spot resistance in cherry (Prunus) is associated with a quantitative trait locus on linkage group 4 inherited from P. canescens. Molecular Breeding 34:927-935. doi: 10.1007/s11032-014-0086-3 24. Szymajda, M., and E. Zurawicz. 2017. ‘Kalipso' European plum. HortScience 52(2):316-319. doi: 10.21273/HORTSCI11425-16 25. Wilcox, W.F. 1992. Black Knot of Plums. Cornell Cooperative Extension, Disease Identification Sheet No. 6. hdl.handle.net/1813/43075 26. Zhivondov, A., and V. Bozhkova. 2010. New Bulgarian plum cultivars. Acta Hortic. 874:345-348, ISHS. doi: 10.17660/ActaHortic.2010.874.49 27. Zhivondov, A., and S. Milusheva. 2016. Characteristics of the new Bulgarian plum cultivar ‘Ostro- mila. Acta Hortic. 1139:63-66, ISHS. doi: 10.17660/ActaHortic.2016.1139.11 OTHER RESOURCES Chong, J., S.A. White, and N.A. Ward. 2012. Cherry - Prunus spp., Chapter 5. In: A.F. Fulcher and S.A. White, editors. IPM for Select Deciduous Trees in Southeastern US Nursery Production. wiki.bug- wood.org/IPM book Dirr, Michael A. 2009. Manual of Woody Landscape Plants: Their Identification, Ornamental Charac teristics, Culture, Propagation and Uses. 6th ed. Stipes Publishing L.L.C., Champaign, IL. Dirr, Michael A. 2011. Dirr's Encyclopedia of Trees & Shrubs. 1st Ed. Timber Press, Inc., Portland, OR. “Missouri Botanical Garden.” missouribotanicalgarden.org “Woody Plants Database” Urban Horticulture Institute, Cornell University. woodyplants.cals.cornell. edu/plant/search

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