Insect Vectors of Witches’ Broom of Sweet Potatoes in Taiwan
H. C. Fang
Studies on the transmission of sweet potatoes withches’ broom were made by using 12 different species of leafhoppers and on species of Aphid collected from the field where sweet potatoes had been damaged by withches’ broom. The results demonstrated that only Orosius ryukyuensis could transmit the disease. The population of Orosius ryukyuensis was now very low in Taiwan, however it may be going higher in the near future. The incubation period of the disease in the sweet potatoes was about 4~5 months in winter, and 2~3 months in summer. The typical symptom showed small and curl leaves on the terminal buds at first, consequently the abnormal branches occurred, and the stunting of the plant was finally resulted no blossoms appeared in the inoculated young plant, but it appeared phyllody in the field.