Oomycetes Root Rot Caused by Pythium spp. and Phytophthora spp.: Host Range, Detection, and Management Strategies, Special Case of Olive Trees

Abstract

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.