Distribution and Management of Fusarium Wilt (Fusarium oxysporum f.sp. lentis) of Lentil (Lens culinaris Medik.) in Central Highlands of Ethiopia
Fusarium wilt of lentil (Lens culinaris Medikus) incited by F. oxysporum f.sp. lentis causes huge lentil yield losses in central highlands of Ethiopia. In this study, extensive one year 2017 wilt survey of eight major lentil-growing districts, viz. Adaa, Aleltu, Lume, Gimbichu, Minjar-Shenkora, Siyadebrena Wayu, Moretina-jiru and Ensaro in central highlands of Ethiopia was conducted. The specific objectives were to: 1) assess the distribution of lentil Fusarium wilt in the central highlands of Ethiopia; 2) determine the extent of seed infection due to lentil Fusarium wilt pathogen on seed lots collected from different sources in the central highlands of Ethiopia; and 3) evaluate the effect of lentil varieties and seedbed preparation methods as components of integrated management option. The results revealed 100% mean wilt prevalence and 32.8% mean wilt incidence. The highest (75%) and the lowest (2%) wilt incidence were recorded in Moretina-jiru and Lume, respectively. Morphology assessment of 192 recovered isolates showed unique identification characters and variability in morphology that differentiated F. oxysporum from other pathogens. Other fungi were isolated at the following frequencies: Fusarium oxysporum f.sp. lentis (100%), Rhizoctonia spp (22.4%) and Sclerotium rolfsii (2.1%). Four levels of lentil varieties, i.e. ILL-590 (susceptible check), Alemaya, Derash and Denbi (improved) and four seedbed preparation methods, including flat bed, open raised bed, tie-raised bed and farmer’s practice, were used as treatments. The treatments were arranged in a factorial experiment in split plot design (SPD) with three replications. The number of seedlings emerged; dead plants due to wilt, and grain yield per plot were recorded for each treatment. Among the seedbed types, the raised seedbed exhibited relatively lower wilt incidence than other types. Interaction of the varieties and seedbed types was significant in wilt reduction. The highest (82.2 and 67.5%) wilt incidence was recorded in the condition of planting ILL-590 susceptible variety on the flat seedbed type, whereas the lowest (25.1 and 8.8%) Fusarium wilt incidences were obtained from planting Derash variety on the raised seedbed preparation method at Debre Zeit and Chefe Donsa, respectively. The highest (1782.5 and 3827.0 kg ha-1) mean grain yields of lentil were obtained from plots where Alemaya and Derash varieties were planted with raised seedbed preparation, while the lowest (64.4 and 68.0 kg ha-1) mean grain yields of lentil were obtained where the plots of the susceptible variety was integrated with flat seedbed type at Debre Zeit and Chefe Donsa, respectively. The highest (1018.0 and 899.4 %unit-days) in AUDPC values were obtained by flat seedbed preparation and ILL-590, while the lowest (342.4; 114.4 %unit-days) in AUDPC values were obtained by raised seedbed preparation and Derash variety at Debre Zeit and Chefe Donsa, respectively. Wilt incidence and AUDPC values were significant and negatively correlated with yield parameters. Also, seed infection due to Fusarium oxysporum f.sp. lentis ranged from 0 to 2%. It was concluded that using resistant variety with raised seedbed significantly reduced Fusarium wilt incidence and gave reasonably high yields. The future research work should focus on screening several lentil genotypes for source of resistance and is suggested to repeat the experiment at several testing locations for one extra season for a conclusive recommendation.