A Preliminary Note on the "Woodiness" Disease of Passion Fruit in Kenya

Abstract

As a garden or ornamental plant, passion fruit (Passifiora edulis) has been grown in Kenya for a number of years, but large-scale cultivation for the manufacture of juice is a comparatively recent development. It was first planted on a commercial scale in Trans Nzoia in 1933 and in Sotik a few months later. The area devoted to this crop has since been considerably extended and is now approximately 1,000 acres, the chief districts being Trans Nzoia, Sotik, and, to a lesser extent, the neighbourhood of Nakuru. The" woodiness" disease appears to have attracted attention early in the life of the industry." Small leaf" was responsible for some loss in Trans Nzoia as easly as 1935. In the Annual Report of the Department of Agriculture for 1936 Ill" woodiness" is recorded as a new plant disease for Kenya and its virus nature is indicated. Early in 1938 Dr. Storey, of the East African Agricultural Research Station, Amani, visited the Colony and obtained material from Trans Nzoia with which he subsequently proved that the disease was caused by a virus which could, under certain conditions, be transmitted by pruning and handling with contaminated hands and knives. In Trans Nzoia the disease has spread extensively and has now assumed alarming proportions. How the disease originated is not known, but it has possibly always existed on some wild host and passed thence to the cultivated passion fruit. It is unlikely that mechanical transmission carries the disease beyond the confines of a single plantation, but there