Study of the Effects of Cailcedrat (Khaya senegalensis) on Late Blight, the Main Onion Disease (Allium cepa L.) in the Department of Diamare, Far North, Cameroon

Objective: Onion (Allium cepa L.) is a vegetable crop with an important economic asset for Cameroonian farmers. The objective of this study is to evaluate the effects of different formulations of K. senegalensis on late blight, the main onion disease in the department of Diamaré, (Far North, Cameroon). Methodology and Results: For this purpose, an experimental split-splot device consisting of three blocks (repeats), comprising three varieties (Chagari, Goudami and Blanc de galmi) of onion and eight treatments (TtN, Ttp, THK1, THK2, TEFK1, TEFK2, TEEK1 and TEEK2) was used in two study sites (Gayak and Wouro-Mayo) and during two agricultural seasons (2020 and 2021). After data collection and analysis, the results obtained show that the mean value of the highest incidence was obtained with Ttn treatment (34.44) in Gayak in 2020, and the lowest value was obtained with THK2 (0.00) in Wouro-Mayo. In 2021, the highest mean value was recorded in Gayak with TtN (32.03) and the lowest incidence is observed with TEEK2 (0.37) in Wouro-Mayo. Moreover, the highest severity was obtained with TtN (17.58) in Wouro-Mayo in 2020, and the lowest with THK2 (0.00) at the same site. In 2021, the lowest severity was observed with THK2 (0.18) in Gayak and the highest with TtN (14.90) in Gayak. The highest yields were recorded with THK2 (160.27 t/ha) at Wouro-Mayo in 2020 and THK2 (169.46 t/ha) in 2021 at the same study site. On the other hand, the lowest yields were obtained in Gayak with TtN (79.6 t/ha) in 2020 and in 2021 with TtN (92.26 t/ha) at the same site. Conclusion and Application of Findings: The oil and aqueous extracts of Khaya senegalensis bark could therefore constitute an alternative to synthetic pesticides in the context of integrated onion disease management.