It is assumed that climate change (global warming) worsens the living conditions for conifers and at the same time favours the cultivation of deciduous trees, including oaks. In fact, in Poland, for example, many more oaks are now being planted as forest-forming tree species than in the 1980s and 1990s. However, the monitoring of the health status of European forests (according to the International Co-operation Project) does not confirm these optimistic assumptions, and oak has been cited as one of the most damaged tree species in terms of defoliation in recent decades. The prospects for oak cultivation in European forestry are therefore a combination of abiotic conditions and biotic damage factors. This review article focuses in particular on the new threats posed by pathogenic organisms causing emerging diseases. These include newly identified bacteria responsible for the so-called Acute Oak Decline (AOD), oomycetes (especially those specialised in damaging fine roots, such as Phytophthora quercina T.Jung) and semi-parasites of the genus Loranthus. At the same time, the pressure from commonly observed insects and fungi described in connection with the complex syndrome of oak decline, which is divided into predisposing, inciting, and contributing factors (according to Manion's disease spiral), has not abated. Therefore, international, interdisciplinary research (such as that proposed in Oakland) is needed, using modern technologies (RS remote sensing) based on the comparison of satellite images (from different years), not only to inventory the most valuable oak stands in Europe (microrefugia) but also to identify trends in changes in their condition and biodiversity. As RS has its limitations (e.g., resolution), aerial monitoring should be complemented by quantitative and qualitative inventory from the ground, e.g., monitoring of the presence of soil microorganisms using effective molecular biological methods (e.g., Next-Generation Sequencing NGS).

Christmas trees are an economically and culturally important ornamental plant in North America. Many microorganisms are pathogens of firs cultivated as Christmas trees. Among those, Phytophthora causes millions of dollars in damage to plantations annually. In Canada, it is unknown which species are responsible for Phytophthora root rot (PRR) of cultivated Abies species. Between 2019 and 2021, soil and root samples were collected from 40 Christmas tree plantations in Qu & eacute;bec province. We used soil baiting and direct isolation from unidentified root fragments to assess the diversity of culturable Phytophthora spp. The obtained isolates were identified using a multilocus sequencing and phylogenetic approach. A total of 44 isolates were identified, including eight P. chlamydospora, eight P. abietivora, seven P. gonapodyides, three P. gregata, six P. megasperma, and two P. kelmanii isolates, plus 10 isolates belonging to a previously unknown taxon that is phylogenetically close to P. chlamydospora and P. gonapodyides. Among the known species, P. abietivora was the most prevalent isolated species associated with trees showing aboveground PRR-like symptoms. Pathogenicity trials confirmed the pathogenicity potential of P. abietivora on both Fraser fir and balsam fir seedlings. Our study provides a first snapshot of the Phytophthora diversity in Qu & eacute;bec's Christmas tree productions and describes multiple potential first associations between Phytophthora species and Abies balsamea and A. fraseri.

Root rot is a damaging disease caused by various pathogenic fungi including, Fusarium spp., Rhizoctonia spp., and especially oomycetes. This disease poses significant challenges to food crop production worldwide. Pythium and Phytophthora, most species of these genera, are fungus-like pathogens that can grow and expand in diverse agroecosystems, inflicting severe damage to the root systems of numerous food crops, including cereals, vegetables, and legumes. Multiple factors contribute to the proliferation of root rot, including temperature, soil moisture levels, and the existence of vulnerable host plants. Based on a wide range of scientific literature, this paper examines the impact of the disease on plant safety, emphasizing the substantial yield losses and economic harm faced by farmers worldwide. The paper provides also a comprehensive overview of the global prevalence, impact, and management strategies associated with root rot infections. A special highlight is directed at symptoms, infection process, and pathogenicity mechanisms employed by Pythium and Phytophthora species, with a particular case of olive root rot caused by these two pathogens. Additionally, detection strategies of pathogenic oomycetes are discussed as well, from conventional to recent tools that are employed now in the plant pathology field. Finally, various preventive and management strategies are provided in this work. These include cultural practices, chemical control measures, and biological control agents, from bacteria to antagonistic fungi with a special focus on the use of Trichoderma spp. strains, and host resistance breeding. The limitations and challenges associated with these strategies, such as the emergence of resistant strains and environmental concerns, are also addressed. In conclusion, this review helps to understand the biology, pathogenicity, and management options for these pathogens, which is crucial for developing sustainable solutions to mitigate the impact of root rot, ensuring food security, and raising sustainable agriculture in the face of this significant challenge.