Effect of tillage method on Fusarium blight severity and yield of soybean in Omu-Aran, Southern Guinea Savannah of Nigeria

Fusarium blight of soybean, caused by Fusarium oxysporum is one of the most destructive diseases of the legume. The pathogen is difficult to control owing to its persistence in the soil and wide host range. Soil tillage practice is one of the most important components of cultural soil management techniques that have a great influence on intensity of plant diseases. This study investigated the effect of tillage practice on the severity of Fusarium blight and yield of soybean. The land used for the trial was artificially inoculated with inoculum suspension of F. oxysporum left for one week before tillage. The experiment was laid out in a randomized complete block design (RCBD) with four treatments, each replicated three times. The treatments consist of ploughing only (P), ploughing followed by harrowing (PH), harrowing only (H) and no tillage (control). The parameters assessed include disease severity, number of pods per plant, pod length, pod weight, 100 seed weight and total seed yield. Findings from this study showed that at 4 weeks after planting, the highest disease severity (1.9) was recorded in soybean planted on ploughed land while the least blight severity (0.8) was recorded with no tillage. Soybean sown under no tillage produced significantly (P<0.05) higher number of pods per plant (41.6) while the lowest pod number (23.3) were produced on soybean sown on ploughed land. Soybean sown under no tillage produced a significantly (P<0.05) higher seed yield (328.0 kg/ha) than all other treatments. Tillage practice is an effective way of managing soybean diseases owing to its potential to adjust soil temperature and moisture. The tillage methods used in the current study incorporated Fusarium blight pathogen at varying soil depths, with no tillage being the most effective approach of reducing the severity of soybean Fusarium blight in infected soil.   Key words: Blight, Fusarium oxysporum, soybean, tillage, disease severity, yield.