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:
“Smoking ... is downright dangerous. Most people who smoke will eventually contract a fatal disease and die. But they don’t brag about it, do they? Most people who ski, play professional football or drive race cars, will not die—at least not in the act—and yet they are the ones with the glamorous images, the expensive equipment and the mythic proportions. Why this should be I cannot say, unless it is simply that the average American does not know a daredevil when he sees one.”
—Fran Lebowitz (b. 1950)
“The Buddha, the Godhead, resides quite as comfortably in the circuits of a digital computer or the gears of a cycle transmission as he does at the top of a mountain or in the petals of a flower.”
—Robert M. Pirsig (b. 1928)