Common rust

Puccinia sorghi

P. sorghi is characterized by the presence of golden-brown to cinnamon-brown pustules (uredinial) that can develop on any above-ground plant part including leaves, husks, tassels and stalks. The uredinia are circular to elongate, and develop with approximately equal frequency on the upper and lower leaf surfaces. The initial symptom is the formation of small chlorotic areas. As the uredinia develop they become erumpent, pushing up the epidermal tissue which eventually splits open to expose masses of powdery urediniospores. Spores often collect in and infect the whorls of the plants resulting in a band of infection across the leaf. On varieties containing genes for the production of anthocyanin pigments, the uredinia may be surrounded by a purple halo. When the disease is severe, large areas of the leaves and leaf sheaths can become first chlorotic then necrotic.

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