Peronosclerospora sorghi is a plant pathogen. It is the causal agent of sorghum downy mildew. The pathogen is a fungal-like protist in the oomycota, or water mold, class. Peronosclerospora sorghi infects susceptible plants though sexual oospores, which survive in the soil, and asexual sporangia which are disseminated by wind. Symptoms of sorghum downy mildew include chlorosis, shredding of leaves, and death. Peronosclerospora sorghi infects maize and sorghum around the world, but causes the most severe yield reductions in Africa. The disease is controlled mainly through genetic resistance, chemical control, crop rotation, and strategic timing of planting. Peronosclerospora sorghi has a broad host range, particularly plants in the sorghum family. These host plants include Sorghum bicolor, or sorghum, Sorghum sudanense, or Sudan grass, and Sorghum palepense, or Johnsongrass. Its hosts also include Pinnisetum glaucum, or pearl millet, and Zea mays, or maize. When maize plants are infected as seedlings, the first symptom to appear is chlorosis of the leaves. As the plant grows, it often shows stunting, and necrotic lesions begin to form on the leaves. As the leaves continue to grow, a white, downy growth may develop in the necrotic lesions, especially on the underside of the leaves. This downy growth is the result of the production of conidia and conidiophores under the proper environmental conditions