also: テングスびょう · テングすびょう
noun
witches' broom; hexenbesen
A plant disease causing dense clusters of small branches, resembling a broom or bird's nest. The Japanese name references tengu (天狗), mythical creatures often depicted with long noses, possibly alluding to the distorted growth.
この桜の木はてんぐ巣病にかかっている。
This cherry tree is affected by witches' broom.
天狗巣病は菌類やファイトプラズマによって引き起こされる。
Witches' broom is caused by fungi or phytoplasmas.
Compound of 天狗 (tengu, a mythical creature) + 巣 (su, nest) + 病 (byō, disease). The name likely comes from the tangled, nest-like growths resembling the disheveled appearance of tengu.