Powdery mildew

Fine white-gray powdery growth on upper leaf surfaces, giving turf a dusted or whitewashed look; leaves may yellow and wither.

Powdery mildew is a fungal disease that affects turfgrass, causing distinctive white, powdery fungal growth on the leaf blades, stems, and other above-ground parts of the plant. The symptoms of powdery mildew typically appear as circular, powdery or felt-like patches on leaves, stems, and other above-ground plant parts. These patches can range in color from white to gray or even yellow, and are usually most severe on the upper leaf surfaces. As the disease progresses, the infected leaves may yellow, become stunted, and die prematurely. In severe cases, powdery mildew can cause significant damage to the turfgrass, leading to thinning and discoloration of the lawn.

Signs of powdery mildew include the characteristic white, powdery coating on the leaf blades, stems, and seedheads. The fungus can also be identified by the presence of small, black, pimple-like structures called pycnidia, which can be found on the infected plant parts. These structures can be observed using a microscope or hand lens.

Powdery mildew is caused by several different species of fungi, including E. graminis. These fungi are obligate parasites, meaning they cannot survive without a host plant. They typically infect leaves, stems, and flowers of the host plant, and can cause significant damage if left untreated. The fungi reproduce asexually, producing a white, powdery growth on the surface of the plant. This growth is composed of mycelia and spores, which are dispersed by wind and can infect new plants.

The epidemiology of powdery mildew in turfgrass refers to the factors that contribute to the spread and development of the disease. These factors include environmental conditions, such as high humidity and warm temperatures, as well as cultural practices, such as high nitrogen fertilization and poor air circulation. The disease is often prevalent in shaded or poorly ventilated areas and can also be spread through infected seed or by spores blown by the wind. The fungus causing powdery mildew, E graminis, can survive in the turfgrass ecosystem through the use of the mycelium and spores, which can survive on infected leaves or in the thatch. The fungus can also survive in the form of chasmothecia, or sexual fruiting bodies, which can survive in plant debris or on weed hosts. The fungus can infect leaves, stems and also the seed head, causing discoloration, deformation and eventually death of the infected plant parts.