Effect of Fertilizer Types on Fungal Disease Incidence in Chili Pepper in Burkina Faso

Chili peppers (Capsicum annuum) are an important crop in the vegetable farming system of Burkina Faso, particularly as a source of income and nutrients for producers. However, their cultivation faces major challenges, namely fungal diseases, the effects and prevalence of which remain poorly understood in the Kadiogo province. Fertilizers, especially organic ones, are regularly used to improve yields, but their effects on disease proliferation have not been studied. This experiment was conducted using a split-plot design with seven varieties as the variable factor and seven fertilizers as the fixed factor. The incidence and severity of the diseases, as well as their interactions, were evaluated. The pathogens were isolated on PDA medium and identified using morphological criteria. The results highlighted Phytophthora capsici as the major pathogen during our experiment. From week 5 onward, the incidence of disease became significant, with values ​​ranging from 0.92 ± 0.07 (T0) to 1.00 ± 0.00 for treatments T3, T4, T5, and T6. Similarly, the severity index increased progressively during weeks 4, 5, and 6, rising from 0.45 ± 0.12 (T0) to levels between 0.75 ± 0.24 and 0.80 ± 0.16 for the most affected treatments (T1, T2, and T3, respectively). NPK treatments recorded the lowest severity at week 6, at 0.51 ± 0.14, while treatments based on poultry manure (T1) at 0.80 ± 0.16; cow dung (T2) at 0.79 ± 0.18 and compost (T3) at 0.75 ± 0.24 were associated with the highest severities. Fertilization alone is insufficient to control pathogen pressure. However, mineral supplementation helped limit the severity of symptoms, indicating improved plant tolerance. Conversely, organic fertilizers appear to promote disease development. Under the conditions of this study, the use of NPK fertilizers seems to be the most effective option for reducing the impact of fungal diseases on chili peppers.