The study assessed the knowledge and control of cassava diseases by farmers in Delta State, Nigeria and the resultant implication for agricultural extension. Data were obtained from 569 cassava farmers by a simple random sampling technique. Data were analyzed by means, percentage, frequency counts and binary logit model. Mean results depicted that cassava farmers in the area were 42.5 years old, spent 13 years in schooling, had a farming experience of 9.5 years and had poor (1.68) annual extension contacts. Extension contact and friends and neighbours were the major sources of information on cassava disease control. Results of the logit regression of the relationship between farmers’ characteristics and knowledge of cassava diseases gave an R2 value of 0.74 indicating that age (negative coefficient), education, farming experience, farm size and extension contact were statistically significant in explaining cassava farmers knowledge of disease control measures. Logit estimates for control of diseases indicated that age, farming experience, farm size and extension contact were statistically significant at P<0.05. Although education was crucial in determining farmers’ knowledge, it was not significant in determining adoption of control measures. The study recommends urgent and good extension contact, good government policy on enlightenment of farmers to improve not only farmers’ knowledge but their adoption of disease control measure as well.