When raised in humid climates it is subject to the attacks of mildew and black-rot.
Downy-mildew, like black-rot, spreads most rapidly and does most injury in hot, wet weather.
Second, foliage particularly susceptible to the attack of mildew and fruit susceptible to the attack of black-rot.
Spraying with bordeaux mixture, as recommended for black-rot, is usually sufficient to keep the disease in check.
Vulpina is less resistant to black-rot than stivalis but somewhat more resistant than Labrusca.
On the other hand the fungus troubles are serious, the black-rot having been especially destructive in some sections.
Unfortunately the fruit is susceptible to black-rot and a little inclined to shrivel after ripening.
Spraying with bordeaux mixture as indicated for black-rot will keep downy mildew in check.
Unfortunately the fruit is susceptible to black-rot and shrivels after ripening.
The species is very susceptible to mildew and black-rot, and like Californica is not resistant to phylloxera.