Gummy stem blight on melon
Reddish gumming associated with crown infection of melon by
gummy stem blight.
Photo courtesy of B. Bruton, USDA-ARS, Lane, OK
Dark
pycnidia (asexual stage= Phoma cucurbitacearum) or pseudothecia
(sexual stage= Didymella bryoniae) form on the surface of stems,
especially for melon and cucumber.
Following
laboratory infection of a melon stem, pycnidia (left) and pseudothecia
(right) develop on the same tissue piece. Note the size difference in
the two fungal structures.Photos courtesy of T.A. Zitter,
Cornell University, Ithaca, NY
Closeup
of pycnidia (asexual stage= Phoma cucurbitacearum) with prominent
ostiole through which conidia are released. 
Individual
pycnidium surrounded by exuding conidia in the shape of a "spore horn"Photos courtesy of T.A. Zitter, Cornell University, Ithaca, NY
Gummy stem blight on stem
Photo courtesy of T.A. Zitter, Cornell University, Ithaca,
NY