The development of a swollen tip at the growing end of a symbiont spore which usually flattens against the host cell surface prior to appressorium formation.
Synonyms:
exact_synonym:
formation of germ tube tip of symbiont on or near the exterior of host; formation of symbiont germ tube hook structure for appressorium development; symbiont germ tube hook structure formation on or near host
related_synonym:
formation of symbiont germ tube hook structure on or near host