Swollen Shoots
This chapter deals with cacao swollen shoot disease, which has wreaked havoc in cacao-growing areas of West Africa since its first report in the early part of the twentieth century. First thought to be caused by drought, it was subsequently found to be caused by a virus—the cacao swollen shoot virus—and to be transmitted between cacao trees by several species of mealybug, including Formicococcus njalensis. Today, we know that ten viruses are involved in causing the disease, which is restricted to West Africa. The chapter examines the transmission of the virus and the efforts made to restrict its spread and reduce its impact. Attempts to tackle the disease have resulted in the destruction of some 300 million trees so far, which gives an indication of the considerable efforts that have been made to contain this devastating disease.