Neofusicoccum parvum

Neofusicoccum parvum is a prominent ascomycete fungus within the Botryosphaeriaceae family. Systematically, it is classified under the kingdom Fungi, phylum Ascomycota, and class Dothideomycetes. It is globally recognized as a significant phytopathogen responsible for a complex of diseases known as Botryosphaeria dieback, which poses a serious threat to viticulture and woody plant cultivation.

The pathogen primarily affects the vascular tissues of host plants, leading to localized necrosis, cankers, and systemic dieback. Key host species include Vitis vinifera (grapevine), various stone fruits, almond, walnut, and several ornamental tree species. The fungus infects the plant primarily through open wounds, such as pruning cuts, cracks caused by hail, or leaf scars, where it colonizes the xylem.

The biological cycle of N. parvum relies on the production of pycnidia, which release large quantities of conidia during rainfall events. These spores are dispersed by water splashes and wind over short and long distances. Additionally, the fungus can produce sexual spores (ascospores) that contribute to the genetic diversity and further dissemination of the pathogen within orchards and vineyards.

Environmental conditions significantly influence the spread of the pathogen. Warm and humid climates are optimal for fungal growth, with temperatures ranging from +20°C to +30°C favoring rapid colonization. Stress factors, such as water deficit, heat stress, and improper vine management, exacerbate the susceptibility of plants, allowing the fungus to progress faster through the plant tissues.

The economic impact of N. parvum is severe, as it leads to progressive decline and eventual death of productive vines and trees. Currently, there is no curative chemical treatment that can eradicate the fungus once it has deeply colonized the woody tissue. Therefore, control focuses on integrated management strategies, including the sanitation of infected wood, thorough disinfection of pruning tools, and preventive application of pruning wound protectants to minimize infection opportunities.