Bacterial Blight of Cotton
Published: 08/29/2023
Bacterial blight of cotton, also known as angular leaf spot and black arm, is an important disease of cotton. It is caused by Xanthomonas citri subsp. malvacearum, and it affects all parts of the cotton plant, reducing yield and fiber quality. Symptoms include water-soaked lesions on leaves constricted by the leaf veins, black lesions on stems and petioles (black arm), and round water-soaked lesions on bolls. The causal pathogen is primarily transmitted through infected seed. However, in situations where continuous cotton is grown, the pathogen can survive on residue on the soil surface for short periods. High humidity, rain, and wind contribute to disease risk and spread.
Bacterial blight on cotton leaf
Travis Faske
Bacterial blight close-up on cotton leaf.
Travis Faske
Managing the disease involves using resistant cultivars, practicing crop rotation, destroying crop residue, and maintaining sanitary practices during ginning and seed processing.
Written and reviewed by Travis Faske, University of Arkansas; Tom Allen, Mississippi State University; and Trey Price, Louisiana State University.
Bacterial blight on cotton leaf. Image by Travis Faske.
Bacterial blight close-up on cotton leaf. Image by Travis Faske.
Bacterial blight on cotton leaf. Image by Travis Faske.
Gallery images courtesy Travis Faske.
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