Molecular Pathogens 2024, Vol.15, No.3, 142-154 http://microbescipublisher.com/index.php/mp 143 reduced growth, increased vulnerability to other pathogens and pests, and, in severe cases, tree mortality. For instance, Dothistroma needle blight, caused by the fungus Dothistroma septosporum, affects the needles, creating lesions that lead to significant defoliation. Similarly, brown spot needle blight, caused by Lecanosticta acicola, results in browning and premature needle drop. Another critical disease is pine wilt disease (PWD), caused by the pine wood nematode (Bursaphelenchus xylophilus), which is transmitted by insect vectors such as Monochamus species. PWD leads to rapid wilting and death of infected trees, severely impacting forest health and timber resources. Diplodia tip blight, caused by Sphaeropsis sapinea, predominantly affects pines under stress, particularly from drought, causing shoot dieback and reduced tree vigor. These diseases are significant concerns for forest managers and researchers due to their widespread impact on pine forests globally. Effective management and control strategies are crucial to mitigate the damage caused by these pathogens and ensure the health and sustainability of pine ecosystems (Raitelaitytė et al., 2017; Blumenstein et al., 2020). 2.2 Pathogens and infection mechanisms Fungal pathogens are the primary cause of many pine diseases, employing various mechanisms to infect and damage host trees. Dothistroma needle blight, for example, is caused by the fungus Dothistroma septosporum, which produces spores that infect needles, leading to characteristic red bands and premature needle drop. Brown spot needle blight, caused by Lecanosticta acicola, follows a similar infection pattern, with spores infecting needles and causing brown lesions that eventually lead to defoliation. White pine blister rust, caused by Cronartium ribicola, has a complex life cycle involving an alternate host, typically a species of Ribes. The rust infects pine needles, spreads to branches, and causes cankers that girdle and kill branches and sometimes the entire tree. The pine wood nematode (Bursaphelenchus xylophilus), responsible for pine wilt disease, is transmitted byMonochamus beetles. The nematode invades the tree’s resin canals, causing water transport disruption, leading to rapid wilting and death. This nematode also has a mycophagous phase, feeding on fungi within the tree, which aids its development and spread (Vicente et al., 2021). The opportunistic pathogen Sphaeropsis sapinea causes Diplodia tip blight, particularly under conditions of drought or injury. This fungus remains latent in healthy tissue until the tree is stressed, at which point it causes significant shoot dieback and reduced growth. These varied infection mechanisms highlight the complexity of managing pine diseases and the necessity for integrated pest management strategies to effectively control these pathogens and mitigate their impact on pine forests (Blumenstein et al., 2020). 2.3 Impact on pine forests and ecosystems The impact of pine diseases on forests and ecosystems is profound, leading to significant ecological and economic consequences. Pine wilt disease, caused by the pine wood nematode (Bursaphelenchus xylophilus), is one of the most destructive diseases, leading to rapid tree death and extensive forest decline. This disease disrupts water transport within the tree, causing rapid wilting and death, which can devastate entire pine stands and significantly reduce timber yields. The economic impact is substantial, with losses in timber value, increased management costs, and reduced ecosystem services. White pine blister rust, caused by Cronartium ribicola, has similarly devastating effects on North American white pine populations. This disease causes cankers on branches and trunks, leading to tree mortality and a decline in forest health. The loss of white pine, a keystone species, disrupts forest ecosystems, affecting biodiversity, wildlife habitat, and forest structure. The economic impact includes loss of valuable timber and increased costs for disease management and forest restoration efforts. Climate change exacerbates these impacts by creating conditions that favor the spread and severity of these diseases. Warmer temperatures and increased drought stress weaken trees, making them more susceptible to
RkJQdWJsaXNoZXIy MjQ4ODYzNA==