WineTasteTV - Offering Wine Education and Information Videos

WINE TERMS

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

mildew

Various fungi that can cause severe damage to vineyards if not treated for prevention. There are two main types—powdery mildew and downy mildew, both of which are partial to VITIS VINIFERA vines (NATIVE AMERICAN GRAPES are resistant). Downy mildew (Plasmopara viticola), also called peronospera, is a major disease in wet, humid grape-growing areas. Native to North America, this fungal disease was first detailed in the early 1800s. By the middle of that century, France (and other European winegrowing regions) were besieged by downy mildew, which caused widespread vineyard damage almost as serious as the PHYLLOXERA epidimic that followed shortly thereafter. The symptoms of this fungus first appear as yellow-green spots on a grape leaf’s upper surface, followed by a fuzzy white growth on the underside. Infected shoots, petioles, or cluster stems become distorted or curled and, under warm, humid conditions, may be covered with a downy growth. Eventually the affected segments wither and brown. Berries are vulnerable until they are pea-size; mature berries are resistant to infection. Powdery mildew (Uncinula necator), also known as oidium, isn’t dependent on moisture like other fungi. It’s found in dryer climates, like California, where most fungi don’t do well, and spreads most rapidly at temperatures between 70 to 86°F. Powdery mildew favors dense canopies (see CANOPY) and attacks all portions of the grapevine, causing young leaves to curl and wither and mature leaves to develop a dark surface stain; the berries can discolor, split, or drop off the vine. When the gray powdery growth is rubbed off of CANES, it reveals dark brown, weblike markings. Most mildews can be controlled by using copper sulfate sprays (see BORDEAUX MIXTURE) or ground or powdered sulfur. See also DISEASES, VINEYARD.
Related Links: Vitis vinifera, phylloxera, native American grapes
© Copyright Barron's Educational Services, Inc.
1995 based on THE WINE LOVER'S COMPANION,
by Ron Herbst and Sharon Tyler Herbst.

WINE TERMS: M

< L M N >

RELATED VIDEO

Sip on this:
Butter me up? Why does my Chardonnay smell like melted butter? Find the Answer
 

Video Index