Neonectria

Neonectria is a genus of filamentous Ascomycete fungi in the family Nectriaceae, order Hypocreales, class Sordariomycetes. Members of Neonectria are primarily associated with woody plants and are best known for forming cankers, dieback, and other wood-rot diseases. The genus includes species with a sexual stage (teleomorph) and, in many cases, a linked asexual stage that has historically been described under different names, such as Cylindrocarpon. Modern taxonomy often recognizes Neonectria in connection with these anamorphs, reflecting a complex taxonomic history.

Ecology and disease ecology: Neonectria species are found worldwide, with many occurring in temperate regions. They are commonly isolated from infected stems, branches, and trunks of fruit trees, hardwoods, and ornamentals. Infections typically enter through wounds or natural openings and can result in localized cankers, girdling lesions, and dieback. Some species can persist as saprobes on woody debris and may reemerge to infect living hosts under stress conditions such as drought, frost, or mechanical damage. The life cycle typically involves production of ascospores from perithecia in the sexual stage, and various conidial forms in the asexual stages.

Economic and agricultural relevance: Neonectria species are important plant pathogens in forestry and horticulture, contributing to canker diseases that reduce vigor, yield, and the longevity of trees and orchard stock. Notable species include Neonectria ditissima, associated with European fruit canker on apple and other Rosaceae, among hosts. Management focuses on sanitation, timely pruning to remove infected tissue, minimizing wounding, and maintaining tree health; fungicides and cultural practices are used selectively depending on the species and crop.

Taxonomy note: the group is subject to ongoing study, with revisions in genus boundaries and species concepts as molecular data illuminate relationships among Neonectria, Cylindrocarpon, and related taxa.