Susceptibility of Fraser, Canaan, and Nordmann Fir to Root Rot Incited by Phytophthora cactorum and Phytophthora drechsleri

Abstract

<jats:p>The susceptibility of fraser fir (<jats:italic>Abies fraseri</jats:italic>), canaan fir (<jats:italic>A</jats:italic>. <jats:italic>balsamea</jats:italic> var. <jats:italic>phanerolepis</jats:italic>), and nordmann fir (<jats:italic>A. nordmanniana</jats:italic>) to phytophthora root rot (PRR) incited by <jats:italic>Phytophthora cactorum</jats:italic> or <jats:italic>P. drechsleri</jats:italic> was assessed in two experiments in central Pennsylvania. In an 8-week greenhouse study, seedlings and transplants growing in soilless substrate were inoculated with <jats:italic>Phytophthora</jats:italic> in flooded and non-flooded settings. In an 8-week outdoor study conducted in raised planting boxes filled with soil, transplants were inoculated with <jats:italic>Phytophthora</jats:italic> species in well-drained and poorly drained soil. Based on foliar disease ratings, mortality rates, and dry shoot and root weights, differences in susceptibility to <jats:italic>P. cactorum</jats:italic> and <jats:italic>P. drechsleri</jats:italic> existed between these true fir (<jats:italic>Abies</jats:italic>) species. Fraser fir was very susceptible to <jats:italic>P. cactorum</jats:italic> and <jats:italic>P. drechsleri</jats:italic>. Canaan fir had strong resistance to <jats:italic>P. cactorum</jats:italic> and <jats:italic>P. drechsleri</jats:italic> in well-drained settings but was susceptible in poorly drained settings. Nordmann fir had very strong resistance to <jats:italic>P. cactorum</jats:italic> and <jats:italic>P. drechsleri</jats:italic> in both well-drained and poorly drained settings.</jats:p>

Survey of the Phytophthora species diversity revealsP. abietivoraas a potential Phytophthora root rot pathogen in Québec Christmas tree plantations

“…Since the mid-2000s, data available for European countries overlap with what is found in the US (Pettersson et al 2019; Shafizadeh and Kavanagh 2005; Talgø et al 2006; Talgø et al 2007; Talgø et al 2017), suggesting that either the association between these Phytophthora species and firs have been longstanding or that, as for other Phytophthora species, worldwide plant trade has contributed to their global dissemination (Bienapfl and Balci 2014; Brasier 2013; Jung et al 2016). While the information currently available connects Phytophthora species to PRR symptomatic trees, few studies have shown their pathogenic potential with Koch’s postulates (Frampton and Benson 2012; Hamm and Hansen 1982; Hoover and Bates 2013; McKeever and Chastagner 2016). Moreover, when Koch postulate are tested, the experiments are usually performed by injuring the tree and directly putting the pathogen at the wounded site (Li et al 2019; McKeever and Chastagner 2016; Pettersson et al 2019; Quesada-Ocampo et al 2009), which does not capture all infection patterns (Hardham 2001; Judelson and Blanco 2005).…”

Oomycete communities are influenced by land use and disease status in Christmas tree production in Southern Québec, Canada

“…In the Eastern United States, at least 17 Phytophthora species have been recorded in association with infections of Abies fraseri ( P. abietivora , P. cactorum , P. cambivora , P. capsici , P. cinnamomi , P. citricola , P. citrophthora , P. cryptogea , P. drechsleri , P. europaea , P. kelmanii , P. megasperma , P. nicotiniae , P. pini , P. plurivora , and P. sansomeana ) (Hoover & Bates, 2013; Huang et al., 2004; Li et al., 2019; McKeever & Chastagner, 2016; Pettersson et al., 2017; Quesada‐Ocampo et al., 2009). However, the situation in Eastern Canada, particularly in Québec, is not as well documented.…”