Leaf petiole and stem blight disease of sweet potato caused by Alternaria bataticola in Uganda

In surveys conducted in 2001-03, the disease incidences in sweet potato ranged from 1 to 49% in Uganda. Symptoms typical of Alternaria leaf petiole and stem blight disease were observed. Symptoms initially manifested as small, dark gray to black oval lesions with lighter lesions centres on stems and petioles. Under humid conditions, lesions enlarged on stems and petioles resulting in petiole and stem girdling. Some leaves exhibited chlorotic and dry symptoms, while brown circular lesions with concentric rings were observed on older diseased leaves. In severe cases, defoliation occurred and soil beneath diseased vines was carpeted with blackened leaf debris. Based on pathogenicity tests and morphological observations, the causal organism was identified as Alternaria bataticola. This communication confirms previous record of sweet potato leaf petiole and stem blight disease caused by A. bataticola in Uganda