Environment
Powdery Mildew thrives in warm, moist environments and infects younger plant tissues like fruit, leaves, and green stems and buds. Free water can disrupt conidia and only requires a humid microclimate for infection. Most infection begins when spring rain (2.5mm) falls and temperatures are approximately 15°C or higher. Rates of infection decline at temperatures higher than 30°C, since the evaporation of water occurs readily. Cooler conditions, such as shading and poor aeration, promote infection due to a higher relative humidity, optimally 85% or greater. However, sporulation does occur at levels as low as 40%. Spores are dispersed mostly by wind and rain splash.
Young underdeveloped tissues are most susceptible to infection, primarily leaves and fruit. Warmer weather cultivars like Vitis vinifera and French hybrids provide overwintering protection in buds and during moderate winters climates. American cultivars are generally less susceptible to infection unless an unusually warm winter does not kill the cleistothecia in buds. Most cleistothecia survive on the vine where ample protection is provided in the bark.
Read more about this topic: Uncinula Necator
Famous quotes containing the word environment:
“Autonomy means women defining themselves and the values by which they will live, and beginning to think of institutional arrangements which will order their environment in line with their needs.... Autonomy means moving out from a world in which one is born to marginality, to a past without meaning, and a future determined by othersinto a world in which one acts and chooses, aware of a meaningful past and free to shape ones future.”
—Gerda Lerner (b. 1920)
“The poorest children in a community now find the beneficent kindergarten open to them from the age of two-and-a-half to six years. Too young heretofore to be eligible to any public school, they have acquired in their babyhood the vicious tendencies of their own depraved neighborhoods; and to their environment at that tender age had been due the loss of decency and self-respect that no after example of education has been able to restore to them.”
—Virginia Thrall Smith (18361903)
“Today the young actors regard their environment with rage and disgust. They regard their Master not as disciples regard their Master, but as slaves regard their Master.”
—Judith Malina (b. 1926)