Field Assessment of the Potential Role of Fusarium Species in the Pathogenesis of Coffee Wilt Disease in Democratic Republic of Congo

Abstract

Aim: To determine the probable role of 3 species of Fusarium (F. falciforme, F. solani and                       F. stilboides) in the pathogenesis of Coffee Wilt Disease (CWD). Study Design: The field trial was performed using a Randomized Completed Block Design (RCBD) replicates three times. Place and Duration of the Study: The study was conduct in the Experimental Garden of Department of Biology, Faculty of Sciences, University of Kinshasa in Democratic Republic of Congo, between November 2005 and February 2006. Methodology: Four Fusarium species (F. falciforme, F. solani, F. stilboides and F. xylarioides) were inoculated alone, or the first three strains were inoculated in combination with F. xylarioides in coffee seedlings 10 months old. Observations were focused on the time of expression of main CWD symptoms, the rate of each symptom observed, and the presence of each pathogen in dead woods of inoculated seedlings.   Results: Results obtained showed that all Fusarium species induced main symptoms of CWD at varying moment and degrees. Chronologically, leaf yellowing appeared an average 25 dai, followed by leaf browning (46 dai), leaf drying (61 dai), mortality (75 dai) and defoliation (77 dai). Significant differences (P = .05) were observed between treatments considered. All Fusarium induced seedlings mortality and were isolated in dead woods at 1 – 4 cm from the point of inoculation. In general, the search of synergistic interaction between Fusarium spp. inoculated in combination with F. xylarioides showed enhanced ability to induce various symptoms of CWD when species are used together.  Conclusion: The present study demonstrates that CWD could be reconsidered as a parasitic complex, and in natural conditions all Fusarium species used present a danger for coffee growing.