However, there are many factors at play, including the prevalence of secondary infecting organisms, the morphological complexity of the tree and the general health status of the individual ash tree.
Fodd bynnag, mae llawer o ffactorau ar waith, gan gynnwys nifer yr achosion o organebau heintio eilaidd, cymhlethdod morffolegol y goeden a statws iechyd cyffredinol yr onnen unigol.