Disease Cycle
The disease cycle of rose powdery mildew starts when the sexual spores, ascospores, of the pathogen survive the winter in a structure composed of hyphae called an ascocarp. The specific ascocarp is a chasmothecium, or cleistothecium, and has a circular shape to it. Under the right conditions the chasmothecium will break open to reveal the asci, which is another long tube-like structure which contain the ascospores. These ascospores are then released and spread by wind, insects, and rain until they land on a susceptible rose for a host and land, attach, and germinate on the plant. They will also produce condia, the asexual spores of Podosphaera pannosa, which will spread throughout the summer. It is these long chains of white conidia which give the fungi its characteristic “powdery” appearance. Late in the year as the plant is dying cleistothecia will again form when the ascogonium receives the nucleus from the antheridium.
Read more about this topic: Podosphaera Pannosa
Famous quotes containing the words disease and/or cycle:
“Man is an exception, whatever else he is. If he is not the image of God, then he is a disease of the dust. If it is not true that a divine being fell, then we can only say that one of the animals went entirely off its head.”
—Gilbert Keith Chesterton (1874–1936)
“The lifelong process of caregiving, is the ultimate link between caregivers of all ages. You and I are not just in a phase we will outgrow. This is life—birth, death, and everything in between.... The care continuum is the cycle of life turning full circle in each of our lives. And what we learn when we spoon-feed our babies will echo in our ears as we feed our parents. The point is not to be done. The point is to be ready to do again.”
—Paula C. Lowe (20th century)