Fungi
Hysterographium - dieback of ashes
Hysterographium fraxini
Thomas Cech
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Fig. 1. Hysterographium fraxini, fruiting bodies
DETECTION PERIOD:
During the whole year.
DESCRIPTION:
Hysterographium fraxini is an ascomycete producing small black fruiting bodies which are visible by the naked eye. To recognize their typical morphology requires the use of a good hand-lens. The fruiting bodies are tiny (around 1 mm or less) erumpent, black, elongated (straight or slightly bent) and bulging showing a longitudinal slit (hysterothecia, Fig.1). They are arranged in small groups on the surface of dead ash-shoots, twigs and branches.
HABITAT:
On ashes in natural habitats, usually in dense young stands.
STATUS:
Commonly a saprophytic species, it can cause dieback mostly of lower branches, which suffer from light deficiency. Predisposing factors are various types of stress: frost, wet soil, permanent high humidity, frequent change of dry and wet periods, nutrient deficiency, damage by insects or any wounds.
IMPACT:
It causes dieback of especially young ashes, sometimes even crown dieback of mature trees. However, usually ashes are not damaged severely.
SIMILAR SPECIES:
None, if the characteristic fruiting bodies are present. Otherwise other causes of dieback, but most of all by Hymenoscyphus fraxineus.
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