Widespread Phytophthora infestations in European nurseries put forest, semi‐natural and horticultural ecosystems at high risk of Phytophthora diseases

Abstract

SummaryAn analysis of incidence of Phytophthora spp. in 732 European nurseries producing forest transplants, larger specimen trees, landscape plants and ornamentals, plus 2525 areas in which trees and shrubs were planted, is presented based on work conducted by 38 research groups in 23 European countries between 1972 and 2013. Forty-nine Phytophthora taxa were recorded in 670 nurseries (91.5%); within these nurseries, 1614 of 1992 nursery stands (81.0%) were infested, although most affected plants appeared healthy. In forest and landscape plantings, 56 Phytophthora taxa were recovered from 1667 of 2525 tested sites (66.0%). Affected plants frequently showed symptoms such as crown thinning, chlorosis and dieback caused by extensive fine root losses and/or collar rot. Many well-known highly damaging host-Phytophthora combinations were frequently detected but 297 and 407 new Phytophthora-host associations were also observed in nurseries and plantings, respectively. On average, 1.3 Phytophthora species/taxa per infested nursery stand and planting site were isolated. At least 47 of the 68 Phytophthora species/taxa detected in nurseries and plantings were exotic species several of which are considered well established in both nurseries and plantings in Europe. Seven known Phytophthora species/taxa were found for the first For. Path. 46 (2016) 134-163 doi: 10.1111/efp.12239 © 2015 http://wileyonlinelibrary.com/ time in Europe, while 10 taxa had not been previously recorded from nurseries or plantings; in addition, 5 taxa were first detections on woody plant species. Seven Phytophthora taxa were previously unknown to science. The reasons for these failures of plant biosecurity in Europe, implications for forest and semi-natural ecosystems and possible ways to improve biosecurity are discussed.

Endemic and Emerging Pathogens Threatening Cork Oak Trees: Management Options for Conserving a Unique Forest Ecosystem

“…Although P. cinnamomi is probably native to tropical regions, this pathogen has become invasive in many Mediterranean areas characterized by prolonged and severe drought conditions (Shearer et al 2004). This ecological adaption is due to the production of long-term survival structures, such as stromata-like hyphal aggregations, thick-walled chlamydospores, and selfed oospores on roots and root debris, enabling the pathogen to survive over unfavorable seasons such as the long, hot, and dry summers typical of Mediterranean ecosystems (Jung et al , 2016.…”

Pathogenicity of Phytophthora isolates originating from several woody hosts in Bulgaria and Poland

“…The outcomes from several research projects, European COST Actions and conferences of the International Union of Forest Research Organizations (IUFRO) proved the threat posed by invasive pathogens (Santini et al 2013). The large-scale analysis of Phytophthora infestations in Europe (Jung et al 2015) has clearly demonstrated that the current international plant health protocols are outdated and seriously flawed. The existing phytosanitary system, despite of the European regulations posed by the European Commission (Directive 2000/29/EC), allows further introductions of potentially invasive Phytophthora pathogens to Europe (Jung et al 2015).…”

“…The large-scale analysis of Phytophthora infestations in Europe (Jung et al 2015) has clearly demonstrated that the current international plant health protocols are outdated and seriously flawed. The existing phytosanitary system, despite of the European regulations posed by the European Commission (Directive 2000/29/EC), allows further introductions of potentially invasive Phytophthora pathogens to Europe (Jung et al 2015). The new holistic and integrated systems approach is urgently required.…”

Pathways to false positive diagnoses using molecular genetic detection methods; Phytophthora cinnamomi a case study

“…Phytophthora species occur worldwide and can be highly invasive plant pathogens (Erwin and Ribeiro 1996;Hansen et al 2012;Jung et al 2013;Jung et al 2015;Scott et al 2013). Phytophthora cinnamomi is widely distributed globally outside its presumed natural range and causes economic losses in both horticulture and in natural ecosystems (Hayden et al 2013).…”