POST-HARVEST FUNGAL ROT OF AFRICAN WALNUT (Tetracarpidium conophorum Mull. Arg) SEEDS IN MBAISE AND THEIR CONTROL USING SELECTED BOTANICALS

Abstract

Information on post-harvest rot of walnut seeds and management options are limited. Therefore, the objectives of this study were to identify fungi causing post-harvest rot of walnut seeds and evaluate efficacy of selected botanicals for their control. Samples of infected walnut fruits were collected from Ahiazu and Ezinihitte, Mbaise, Imo State and fungi isolation from the seeds was done using standard procedures.  Clove and West African pepper (WAP) were evaluated in vivo and in vitro for fungi growth inhibition. Experiments were laid out in CRD in triplicates. Data were analysed using ANOVA at α_0.05.  Fusarium solani, F. oxysporum, Rhizopus stolonifer, Lasidioplodia theobromae, Aspergillus flavus, A. tamarii, A. flavus and Penicillium sp were isolated. WAP+clove reduced L. theobromae (75.17%) growth better than clove (17.24%) or WAP (72.72%) and were significantly (p=0.05) higher than control (0%). For Rhizopus, WAP showed 98.99% rot reduction, while clove and WAP+clove recorded 45.55% and 71.04% inhibition respectively Aspergillus flavus growth was reduced up to 98.79% by WAP, 82.02% by WAP+clove and 54.46 by clove.  Aspergillus niger growth inhibition by WAP was 100%, followed by WAP+clove (76.51%), while clove was 71.19%.  Mycelia growth inhibition for F.  oxysporum was inhibited by 91.12 % using WAP extract, followed by WAP+clove (80.01%), while clove induced 67.57% inhibition. Fusarium solani growth was inhibited by up to 98% by WAP and WAP+clove extracts, while clove had 46.49 % inhibition. Fungal rot reduction by clove ranged from 36.67-100%, 46.67-96.67% by WAP and 65-96.67% for WAP+clove. This study showed that crude extracts of clove and WAP in single and combined applications significantly inhibited fungi mycelia growth and rot development.