Dina Ribeiro

Fusarium circinatum, the causative agent of pine pitch canker disease, is a pathogenic fungus that poses a significant threat to pine forests globally. It infects various Pinus species, causing resinous cankers, needle discoloration, and tree death. The disease severely impacts forest ecosystems, necessitating cost-effective and environmentally friendly management strategies. Contaminated pine seeds and seedlings are the main pathways for introducing this fungus to disease-free areas. To mitigate this disease and prevent its spread, it is crucial to implement new processes in forest plant production systems that align with the existing conditions of forest nurseries, ensuring effective and sustainable management. With this in mind, a national collaborative study involving 14 Portuguese partners was initiated to develop new prevention and mitigation strategies. In this work, four different treatments—MennoFlorades, Captan, ethanol, and hot water—were tested for their ability to eliminate F. circinatum from contaminated Pinus seeds in vitro. The most effective treatments were selected for further in vitro assays and real-context nursery germination trials to assess their impacts on seed germination, plant production, and certification. MennoFlorades, Captan, and hot water were tested in the nursery, with hot water showing the most promising results due to its negligible impact on seedlings, eco-friendly nature, ease of implementation, and cost-effectiveness. These findings offer promising prospects for preventing pine pitch canker outbreaks in nurseries and, consequently, in forests.

Fusarium circinatum is one of the many threats to forests and Pinus nurseries all over the world, being classified as a quarantine organism by several organizations and governing bodies, such as the European and Mediterranean Plant Protection Organization (EPPO) and the European Union (EU), with associated phytosanitary measures in place to prevent its spread through the various means of dispersal. One such means of dispersal is the water used for irrigation in nurseries, which can contain fungal propagules. Three different treatments, namely, Desogerme, Intra Hydrocare and sodium hypochlorite (NaClO), were tested for their efficacy in eliminating F. circinatum spores in water at several concentrations. Those that showed 100% disinfection rates were selected for further assays regarding seed germination and water quality impact. From these studies, Desogerme 1% and Intra Hydrocare 4% were then selected for large-scale seed germination and plant certification assays in nurseries, where they showed promising results in regard to the prevention of infections in nurseries, and in this way, contribute to the efforts of mitigating this disease.