Incidence and Severity of Taro Leaf Blight (Phytophthora colocasiae Raciborski) in the Sudanian Climatic Zone of Burkina Faso

Abstract

Taro leaf blight is considered the most destructive disease affecting taro worldwide. In the Sudanian climatic zone of Burkina Faso, the disease has led to a consistent decline in taro production over recent years. Aims: The current research study was aimed to determine the incidence and the severity of taro leaf blight in various taro fields in three provinces of the sudanian climate zone. Methodology: Plant growing conditions were assessed in 27 fields. Data on healthy and diseased plants, and leaves per plant, were collected within 64 m² quadrats. Disease incidence was the percentage of infected plants per field. Severity was rated on a 12-point scale (0–11) and converted to percentage of affected leaf area, averaged over 10 plants per field. Infestation intensity was calculated as the ratio of infected to total leaves per plant. Place and Duration of Study: Surveys were conducted in fields across the provinces of Houet, Kénédougou, and Comoé between June and July 2021. Results: Phytophthora colocasiae was morphologically identified from diseased taro samples based on the shape of sporangia, mycelial structure, colony characteristics, and the presence of chlamydospores, revealing morphological variability. The results showed that the disease was widespread across all three surveyed provinces, with notable differences in severity. The local variety Tabouchi, which is highly susceptible to leaf blight, was found in 88.88% of the surveyed fields. In contrast, the exotic variety BL/SM/120, known for its higher tolerance to the disease, was grown by only a minority of farmers. Disease incidence and intensity exceeded 50% in all provinces, with Kénédougou recording the highest severity (31.85%), followed by Houet (20.21%), and Comoé with the lowest (13.80%). Conclusion: These results indicate that leaf blight constrains taro cultivation in these provinces. They also lay the groundwork for developing effective control strategies to safeguard taro production in the Sudanian climate zone of Burkina Faso.