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:
“We learn through experience and experiencing, and no one teaches anyone anything. This is as true for the infant moving from kicking to crawling to walking as it is for the scientist with his equations. If the environment permits it, anyone can learn whatever he chooses to learn; and if the individual permits it, the environment will teach him everything it has to teach.”
—Viola Spolin (b. 1911)
“White males are the most responsible for the destruction of human life and environment on the planet today.”
—Robin Morgan (b. 1941)
“Maturity involves being honest and true to oneself, making decisions based on a conscious internal process, assuming responsibility for one’s decisions, having healthy relationships with others and developing one’s own true gifts. It involves thinking about one’s environment and deciding what one will and won’t accept.”
—Mary Pipher (20th century)