Twenty-five percent of Nigeria's Soybean production are been consumed in rural areas. Several biotic and abiotic factors constraint production of soybean, resulting in yield decline. Soil tillage practices is an integral components of cultural soil management practices that impacted diseases. This work, therefore, looks into the effect of three cultural practices on the incidence and intensity of soybean diseases, vis-à-vis their yield. This work was carried out at the Research Field, of National Cereal Research Institutes, Ibadan, in 2020 cropping seasons, using Randomized Complete Block Design in triplicate. Factors are ploughing only (P), ploughing + harrowing (PH), and no-tillage (NOT). Plants were selected from each plot for disease symptoms assessment visually. Data on percentage disease occurrences were analyzed. Means separated by LSD at P=0.05. Disease incidence and severity varied significantly with tillage methods. At 10 weeks after sowing, ploughing alone record significant higher diseases of 29.17% for leaf blight than other tillage methods while plough + harrowing had significantly lower disease incidence for the same disease. Ploughing + harrowing produced a higher seed yield of 2724.83 t/ha, followed by no-tillage (2165.93 t/ha). This study shows that the tillage method affects disease development in Soybean. Further studies on multi-locational field evaluations of the impact of tillage practices on soybean diseases are required.

Keywords : Soybean, Nigeria, Tillage; Ploughing + Harrowing, Disease Incidence.