Study of Cultural and Morphometric Characters of Fusarium xylarioides Strains Isolated from Coffee Trees Infected with Coffee Wilt Disease Collected from Eastern, North Kivu and Equateur Provinces, Democratic Republic of Congo

摘要

Aim: To determine cultural and morphometric characters of different strains of Fusarium xylarioides isolated from coffee trees collected from Eastern, North Kivu and Equateur provinces of Democratic Republic of Congo (DRC). Study Design: The study was performed using a completely randomized design with three replications. Place and Duration of the Study: The study was conducted in the laboratory Unit of Phytopathology, Faculty of Agronomy, University of Kinshasa, between January and February 2005. Methodology: Seventeen F. xylarioides strains collected from the eastern, North Kivu and Equateur province were isolated from coffee trees infected with CWD. They were grown in Synthetic Nutrient Agar (SNA) and Potato Glucose Agar (PGA) culture medium. For each strain, characteristics based on radial growth, mycelial pigmentation and contour of disc, size and morphology of conidia, and density of sporulation were studied. Results: The results obtained showed that different strains of F. xylarioides are characterized with rapid rate of growth (3.76 – 4.14 mm/day), slow rate of growth (3.36 – 3.74 mm/day) and very slow rate of growth (2.78 – 2.98 mm/date). In general, 70.5% of strains had cream pigmentation, 23.5% had purple and 6% had cream to purple pigmentation. Seventy-six percent of strains presented a slightly sinuous mycelial disc, while 24% had sinuous disc. Different strains produced 84.9% of sickle conidia, while 15% of conidia were curved; and 67.7% of microconidia had allantoid form, while 32.1% had a reniform shape. Microscopic observations revealed that macroconidia size varied from 7.1 – 13.31 x 1.7 – 2.45 μm, and microconidia varied from 3.55 – 6.15 x 1.65 – 2.42 μm. All macroconidia presented a single partition, while microconidia were devoid of any partition. The strains studied produced an average 200 – 800 conidia/ml. Conclusion: The results of the present study revealed that F. xylarioides presents a plasticity for different characters studied.