Sorghum Downy Mildew (fungus - Peronosclerospora sorghi): Young, systemically infected plants have light green to yellowish stripes lengthwise in the leaves often with a grayish-white downy fungal growth consisting of numerous tiny spores on the lower surface of the leaf opposite the pale striped areas. Soil-borne spores cause systemic infection of the young seedlings. These systemically infected plants will not produce heads. Later infections may parially or completely inhibit grain formation. Plants can also be infected by air-borne spores from the underside of infected leaves. These infections result in localized leaf lesions. Grain sorghum hybrids vary considerably in their susceptibility. Growers should select adapted, high producing hybrids that have resistance to this fungus. Growing highly susceptible grain or forage sorghum builds up populations of the organism in soil, making the problem more severe even in resistant hybrids. Use seed treated with a systemic fungicide containing metalaxyl and resistant hybrids to control this disease.
