Fraser fir was the most valuable cut Christmas tree species in the United States in 2009, accounting for $89.1 million in sales for producers (U.S. Department of Agriculture, 2009). In the past two decades, demand for fraser fir has increased and consumers now consider it a premium product (Chastagner and Benson, 2000; Tompkins, 2000; Williams, 2002). This demand has resulted in production of fraser fir in sites ill-suited to the species, including poorly drained soils (Johnson, 2009; Owen, 2005). The limiting factor in fraser fir Christmas tree production on poorly drained sites is PRR, which may be incited by several Phytophthora species (Benson et al., 1976; Kuhlman and Hendrix, 1963; Quesada-Ocampo et al., 2009; Shew and Benson, 1981). Fraser fir specimens with PRR symptoms sent to the Pennsylvania Department of Agriculture Plant Diagnostic Laboratory between 1986 and 2011 most frequently contained P. cactorum, P. cryptogea, or P. drechsleri (T. Olson, personal communication).
Fraser fir is considered very susceptible to PRR, with minor differences in susceptibility occurring between seed sources (Frampton and Benson, 2004). Canaan fir is closely related to fraser fir and has been reported to survive in soils conducive to PRR (Brown, 2000; Potter et al., 2010). Greenhouse and shadehouse testing of multiple seed sources of canaan fir two-year-old and three-year-old seedlings growing in soilless substrate in North Carolina found susceptibility to P. cinnamomi in all seed sources, although some variation in degree of susceptibility occurred (Benson et al., 1998b).
Studies conducted in North Carolina indicate variation in resistance to P. cinnamomi exists between true fir species as containerized seedlings in soilless substrate, with the greatest tolerance or resistance to P. cinnamomi being observed in momi fir (A. firma) and turkish fir [A. nordmanniana ssp. equi-trojani (syn. A. bornmuelleriana)] (Benson et al.,1998a; Hinesley et al., 2000). In the Benson et al. (1998a) study, nordmann fir had less severe foliar symptoms than fraser fir but was still determined to be very susceptible to P. cinnamomi.
Despite having considerable resistance to P. cinnamomi, momi fir has little potential as a cut Christmas tree crop because of its morphological features and susceptibility to spring frost damage (Hibbert-Frey et al., 2010; Hinesley and Frampton, 2002). Turkish fir is a better candidate as a cut Christmas tree crop and is considered either a natural hybrid between greek fir (A. cephalonica) and nordmann fir or a subspecies of nordmann fir (Farjon, 2010; Liu, 1971). The close relationship between turkish fir and nordmann fir suggests that nordmann fir might possess Phytophthora resistance genes. Nordmann fir is more readily available in the U.S. conifer industry than turkish fir and additional testing on its resistance to PRR-inciting Phytophthora is warranted.
This study involved testing fraser fir, canaan fir, and nordmann fir for resistance to PRR incited by P. cactorum or P. drechsleri. Inoculation tests were done in a 2009 greenhouse experiment with seedlings and transplants growing in soilless substrate and in a 2010 outdoor experiment in planting boxes containing transplants growing in soil, with a flooding treatment included to create conditions favorable for PRR.
Bates, R.M., Sellmer, J.C. & Despot, D.A. 2004 Postharvest characteristics of canaan fir and fraser fir Christmas trees HortScience 39 7 1674 1676
Benson, D.M., Hinesley, L.E., Frampton, J. & Parker, K.C. 1998a Evaluation of six Abies spp. to phytophthora root rot caused by Phytophthora cinnamomi Biol. Cult. Tests Control Plant Dis. 13 57
Benson, D.M., Hinesley, L.E. & Parker, K.C. 1998b Evaluation of canaan seed sources for resistance to phytophthora root rot caused by Phytophthora cinnamomi Biol. Cult. Tests Control Plant Dis. 13 58
Brown, J.H. 2000 Survival and growth of trees of a Canaan Valley, West Virginia, seed source in relation to varying soil/site conditions. Ohio State Univ. Ext. Spec. Circ. 175-00
Chastagner, G.A. 2001 Fir diseases, p. 152–156. In: R.K. Jones and D.M. Benson (eds.). Diseases of woody ornamentals and trees in nurseries. APS Press, St. Paul, MN
Chastagner, G.A. & Benson, D.M. 2000 The Christmas tree: Traditions, production and diseases. Plant Health Prog., doi: 10.1094/PHP-2000-1013-01-2V
Farjon, A. 2010 A handbook of the world’s conifers. Vol. I. Brill, Leiden, The Netherlands
Hibbert-Frey, H., Frampton, J., Blazich, F.A. & Hinesley, L.E. 2010 Grafting fraser fir (Abies fraseri): Effect of grafting date, shade, and irrigation HortScience 45 4 617 620
Hinesley, E. & Frampton, J. 2002 Grafting fraser fir onto rootstocks of selected Abies species HortScience 37 5 815 818
Hinesley, L.E., Parker, K.C. & Benson, D.M. 2000 Evaluation of seedlings of fraser, momi, and siberian fir for resistance to Phytophthora cinnamomi HortScience 35 1 87 88
Hoover, B.K. 2012 Fungicide efficacy in prevention of root rot incited by Phytophthora cactorum and Phytophthora drechsleri in fraser fir seedlings HortTechnology 22 4 470 475
Johnson, J.E. 2009 Species for Christmas tree planting in Virginia. Virginia Coop. Ext. Virginia Polytechnic Inst. State Univ. 420-082
Józsa, A., Bakonyi, J., Belbahri, L., Nagy, Z.Á., Szigethy, A., Bohár, G. & Woodward, S. 2010 A new species of Phytophthora reported to cause root and collar rot of common boxwood, nordmann fir and port orford cedar in Hungary Plant Pathol. 59 6 1166 1167
Kang, S. 2012a Phytophthora database: Isolate browser: PD_00551. 31 Mar. 2012. <http://www.phytophthoradb.org/isolate.php?a=dv&id=551&p=17&l=30&sv=&sf=>
Kang, S. 2012b Phytophthora database: Isolate browser: PD_00640. 31 Mar. 2012. <http://www.phytophthoradb.org/isolate.php?a=dv&id=640&p=3&l=30&sv=&sf=>
Madsen, S.F. 1994 Provenance trial of Abies nordmanniana and Abies bornmülleriana for Christmas tree production in North Sealand For. Landscape Res. 1 2 143 166
Nielsen, U.B. & Chastagner, G.A. 2005 Variation in postharvest quality among nordmann fir provenances HortScience 40 3 553 557
Owen, J.H. 2005 Selecting sites for fraser fir production. North Carolina State Univ. Coop. Ext. Christmas Tree Notes CTN-036
Potter, K.M., Frampton, J., Josserand, S.A. & Nelson, C.D. 2010 Evolutionary history of two endemic Appalachian conifers revealed using microsatellite markers Conserv. Genet. 11 4 1499 1513
Quesada-Ocampo, L.M., Fulbright, D.W. & Hausbeck, M.K. 2009 Susceptibility of fraser fir to Phytophthora capsici Plant Dis. 93 2 135 141
Talgø, V., Herrero, M.L., Toppe, B., Klemsdale, S.S. & Stensvand, A. 2007 Phytophthora root rot and stem canker found on nordmann and subalpine fir in Norwegian Christmas tree plantations. Online. Plant Health Prog., doi: 10.1094/PHP-2007-0119-01-RS
U.S. Department of Agriculture 2009 Census of horticultural specialties. Vol. 3. Part 3. U.S. Dept. Agr. AC-07SS-3
Williams, R. 2002 Evaluation of the competitive position of the fraser fir Christmas tree. 1 Apr. 2012. <http://www.ncagr.gov/stats/crops/ChristmasTreeBuyers2001.pdf>