Effect of Different Soil Fertilities on Cowpea Mosaic Virus Disease Incidence

The present study was done to determine the effect of different soil fertilities on cowpea mosaic virus disease incidence. The fertilities were; 50 kg/ha Diammonium phosphate (18.46.0), 50 kg/ha Mavuno (10.26.10) that is a mineral fertilizer that has been extensively utilized in western Kenya, 3 tons/ha farmyard manure (FYM), FYM/Mavuno combination with half rate of the latter at 25 kg/ha, FYM/DAP combination with half rate of the latter at 25 kg/ha and unfertilized control, all applied at planting time. Certified cowpea seed of K80 variety was planted using the different fertilizers in a randomized complete block design (RCBD). Percent cowpea mosaic disease incidence (DI) data was collected and analyzed through one-way ANOVA. Fisher's LSD post-hoc test at 5% level of confidence was used to evaluate the nature of the differences in mean DI. The results of cowpea mosaic DI shown as descriptive statistics collected from the six fertilizer treatments indicated that FYM/DAP combination had the smallest mean for DI (M = 12.55), while DAP alone had the highest DI mean (M = 33.97). Associations among groups in the ANOVA table showed that the fertilizer effects were significant (p < .005). The measure of effect size showed that 92% of the variance in DI was accounted by the type of fertilizer treatment applied. In conclusion, application of DAP combined with FYM at 25 kg/ha and 1.5 tons/ha was found to be helpful in lowering the cowpea mosaic virus infection in the region where this study was carried out, though these could be used with knowledge of soil reaction. Abbreviations: ANOVA, Analysis of variance; DAP, Diammonium phosphate; DI, Disease incidence; FYM, Farmyard manure; HRI, Horticulture Research Institute; LSD, Least significant difference; KALRO, Kenya Agricultural and Livestock Research Organization; NRF, National Research Fund; RCBD, Randomized complete block design; SPSS, Statistical package for social sciences