Evaluation of potential sources of inoculum for the coffee wilt epidemics in Uganda

Abstract

Studies were conducted at Coffee Research Institute (CORI) to determine various sources of inoculum for Fusarium xylarioides (F.X), the causal agent of coffee wilt disease (CWD). Coffee seedlings of between 5-6 months were inoculated with F. xylarioides spores obtained in situ from perithecial stroma around the bases of infected coffee trees. F. xylarioides inoculum raised in culture initially obtained from infected coffee tissue was also used. Furthermore, an attempt was made to isolate F. xylarioides from the stalks of the coffee berries/seeds. Results suggest that disease was higher on seedlings inoculated with spores from perithecial stroma than inoculum raised under laboratory conditions from infected coffee tissue. Inoculation by root dip in spore suspensions gave highest disease incidence of up to 100% and was the most effective. In all cases where inoculation was done on leaves, no coffee wilt disease symptoms developed. However, when stems were inoculated by pricking above the level of the fourth leaf, wilt symptoms were observed only on the upper section and none on the lower. The section below the point of inoculation continued to produce healthy tillers even 100 days after inoculation. The studies concluded that F xylarioides spores collected from infected

coffee stems and inoculated in situ cause CWD and these together with infected coffee stalks could be the avenues through which the pathogen spreads.