Best practices and methods for telial and aecial host inoculations with Cronartium ribicola, causal agent of white pine blister rust

Forest pathologists and tree breeders working with obligate biotrophs, such as rust fungi, depend on effective inoculation protocols for their studies. These protocols are crucial for advancing the understanding of pathogen biology and for selecting disease-resistant hosts. Over a century of research on the white pine blister rust pathogen, Cronartium ribicola, has greatly enhanced our knowledge of the optimal conditions for its collection, preservation and host inoculation. However, since C. ribicola cycles between two phylogenetically distinct hosts, research often focuses on only one part of the lifecycle, leading to the scattering of information on inoculation conditions and techniques across numerous studies. Additionally, evolving insights into C. ribicola biology have led to changes in methods over time, resulting in a variety of inoculation protocols for resistance screening programs and pathogen biology studies. Therefore, there is a need for an updated comprehensive framework that covers inoculation protocols for all critical life stages of C. ribicola. This review aims to consolidate decades of practical experience and scientific knowledge to provide valuable and adaptable information for future studies involving C. ribicola.