Powdery mildew is caused by a fungus and is seen as a light gray or whitish powder on the surface of leaves. See: Greenhouse Plants, Ornamental-Powdery Mildew. But zinnia lovers needn't forgo the cheerful blooms. Many commonly grown annual and perennial flowering plants, as well as ornamental grasses, can be infected by powdery mildew. Zinnia-Powdery Mildew. It travels by airborne spores, and thrives when nights are moderately cool and foliage stays damp. Zinnia – Powdery mildew. THE NINE-ZINNIA TEST . ʻMagellanʼ), an experiment was carried out as a factorial experiment in the form of a randomized complete block design with two factors including eight treatments and three replications. Overwinters as either chasmothecia or conidia on infected plants. By Lynn Byczynski. Jay W. Pscheidt, 2014. Powdery mildews are one of the most common diseases of ornamental plants; many nursery,flower, and woody plants are susceptible. Powdery mildew, common on zinnias and other crops in mid-summer, starts with just a few spots on the lower leaves, as shown in this photo. Powdery mildew is a fungus that appears as gray or white splotches on leaves, stems and flowers of zinnias and other ornamentals and some vegetable plants. Cause Golovinomyces spadiceus (formerly Erysiphe cichoracearum), a fungus. Death of the plant is rare. It occurs following warm days and cool nights often being seen in the fall and spring. … Powdery mildew can cover leaves and stems late in the growing season. Let’s not complain!” Of course, no sooner had a I said that, then I saw this out on our zinnias: Yes, my friends, that is none other than the pesky fungus, Powdery Mildew. You can expect great performance from several types--even in powdery mildew country. Heavy mycelial growth can be seen late in the growing season. Greenhouse crops prone to infection include African violet, Begonia, Dahlia, gerbera daisy, Hydrangea, roses, Verbena, Kalanchoe, and poinsettia. Dreamland, Peter Pan, Rainbow, Ruffles, and Sunshine have 2- to 3-inch-wide leaves and large (3- to 3 1/2-inch-wide) double flowers. Powdery mildew affects over 10,000 plants. Symptoms and Diagnosis. A mild covering of powdery mildew is merely unattractive, but a severe case can cause distorted shoots and leaves, misshapen flowers, or … Zinnias always get powdery mildew!” My brilliant answer to that question was, “Well, for some reason the weather has not been as good for mildew this year. We grew and monitored nine types of zinnias. The disease is considered more unsightly than harmful. Zinnia, phlox, bee balm and peony are a few of the plants regularly infected by powdery mildew in the flower garden. Jay W. Pscheidt, 2014. the reduction of the powdery mildew damage to Zinnia (Zinnia elegans Jacq. Without treatment, it will spread to shoots and buds and eventually kill the plant. As warm, dry weather settles in this month, be alert for the development of powdery mildew on crops.