The pustules on the surface are due to fructifications, pycnidia and spermagonia.
The latter for a time retains its plumpness, but on the appearance of little black pustules, which first occur on the part primarily affected, the grape begins to shrivel.
Plasmopara, &c. In Cystopus (Albugo) the "conidia" are abstricted in basipetal chain-like series from the ends of hyphae which come to the surface in tufts and break through the epidermis as white pustules.
discolour discolored patches of bark form white pustules in summer & red fruiting bodies in winter.
It is characterized by firm papules and pustules at the nape of the neck.