Phytophthora chlamydospora

Species  profile prepared by E. Hansen, P. Reeser, and W. Sutton. 

To cite, see Forest Phytophthoras (2018) doi: 10.5399/osu/fp.8.1.4566

Disease History: 

P. chlamydospora is found in streams and wet soil worldwide (Table 1). It is occasionally recovered from cankers on trees and roots in forest situations (Reeser et al. 2008, Navarro et al. 2014, Sims et al. 2014). It has been associated with root rot of Port-Orford cedar (Chamaecyparis lawsoniana) in German nurseries, where it was initially misidentified as P. lateralis (Hansen et al. 1999), and with root rot and stem cankers of Abies species in nurseries and Christmas tree plantations, where it was originally misidentified as P. drechsleri (Brasier et al. 1993). On horticultural hosts, P. chlamydospora causes root and crown rot of walnut, almond, and cherry trees (Dervis et al. 2016, Turkolnez et al. 2016, Kurbetli et al. 2017) and foliar lesions and shoot dieback on several ornamental species in nurseries (Jung and Blaschke 2004, Schwingle and Blanchette, 2008, Yakabe et al. 2009, Blomquist et al. 2012, Prospero et al. 2013, Ginetti et al. 2014).

Impacts in the Forest: 

Apart from its riparian habitat P. chlamydospora has been associated with what may be largely opportunistic root infections of Abies and Pseudotsuga in Christmas tree plantations, root rot of ornamental Prunus and Chamaecyparis; and, in one instance, with stem cankers on tanoak (N. densiflorus) in a natural forest (Table 1). Artificial inoculations of several plant species have confirmed that P. chlamydospora can be pathogenic on stems and roots (Navarro et al. 2014, Reeser et al. 2008). However, true status of P. chlamydospora as a pathogen in forests has yet to be established. Where it is locally abundant in streams there is usually no visible evidence of disease in adjacent vegetation. In contrast, P. chlamydospora appears to be a pathogen of horticulturally valuable species in managed systems where it can cause both root and foliar disease on a range of woody hosts.

Forest and Wildland Hosts and Symptoms: 

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