Abstract:

Studies were conducted at Coffee Research Institute (CORI) to determine various sources of inoculum for
Fusarium xylarioides (EX), the causa! agent of coffee wilt disease (CWD). Coffee seedlings of behveen 5-6
months were inoculated with E xylarioides spores obtained in situ from perithccial 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 E xylarioides from the stalks of the coffee
berries/seeds. Results suggest that disease was higher on seedlings inoculated with spores from perithccial
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.