In vitro Evaluation of the Fungicidal Potential of Aqueous and Methanolic Extracts of Thevetia peruviana on the Development of Rigidoporus lignosus, Causal Agent of White Root rot of Hevea brasiliensis

Aims: The objective of this work is to evaluate the effect of (aqueous (EAq) and methanolic (ME)) extracts of Thevetia peruviana on the in vitro development of Rigidoporus lignosus.

Study Design: A synthetic fungicide (Onazol 100), two extracts at differents concentrations: C1 = 3.5 mg / ml; C2 = 7 mg / ml; C3 = 15 mg / ml; C4 = 30 mg / ml; C5 = 50 mg / ml and C6 = 100 mg / ml for EAq; C1 = 3.5 ml/ml; C2 = 7 ml/ml; C3 = 15 ml/ml; C4 = 30 ml/ml; C5 = 50 ml/ml for ME and a negative control (T = 0 mg / ml) were used.

Place and Duration of Study: The study was conducted in pathology laboratory at University of Yaounde I and IRAD of Nkolbisson in 2018.

Methodology: Daily measurements of the pathogen's development was used to evaluate the average growth (D) of the mycelium. The inhibition percentages of the different doses of EAq, ME and ONAZOL 100 were calculated after 4 to 5 days of growth of the fungus.

Results: The major result obtained compared to the rate of rot showed that the treatments EAq, ME (C6) and ONAZOL 100 were closed. The disease rates at different concentrations of C1 to C6 were 13.91 to 100% for ME, 9.34 to 100% for EAq, and 100% for ONAZOL 100.

Conclusion: The two extracts are promising, and on small and medium scale, could be an effective and cheap formulation for the control of Rigidoporus lignosus.