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The efficacy of botanical pesticides for managing powdery mildew, Oidium anacardii Noack disease in cashew, Anacardium occidentale L. plantations in Tanzania

Author Affiliations

  • 1Naliendele Agricultural Research Institute, P.O. Box 509, Mtwara, Tanzania
  • 2Naliendele Agricultural Research Institute, P.O. Box 509, Mtwara, Tanzania
  • 3Naliendele Agricultural Research Institute, P.O. Box 509, Mtwara, Tanzania

Res. J. Agriculture & Forestry Sci., Volume 5, Issue (10), Pages 1-6, October,8 (2017)


Powdery Mildew Disease (PMD), which is caused by fungus Oidium anacardii is a serious devastating disease to cashew (Anacardium occidentale L.), can cause significant losses in both yields and quality if not controlled. Extracts from plants play a significant role in crop protection strategies. We conducted field experiments in 2014 and 2015 cashew seasons to test botanicals’ efficacy against cashew PMD in Tanzania. Five plants were used, namely; Opuntia ficus-indica, Opuntiavulgalis, Euphobia tirucalli, Azadirachta indica and Bobgunnia madagascariensis. Tridimenol (250 EC), a synthetic fungicide was used as control standard. A Randomized Complete Block Design was used with four replications. A net plot consists of two cashew trees and ten panicles from each cashew tree were selected and used as experimental unit. Knapsack hand sprayer was used for fungicides applications, and spraying was done in a fortnight’s interval. The results indicate that, cashew trees treated with extracts from O. ficus-indica consistently recorded lower (between 16 and 32%) PMD infection compared to other botanicals (32 and 58%). Cashew trees treated with Triadimenol 250 EC, a synthetic fungicides recorded<7% PMD infection. However, due to negative environmental effects posed by these synthetic pesticides, plant extracts from O. ficus-indica can be a potential candidate to smallholder farmers for cashew protection against fungal disease caused by Oidium anacardii. Further studies are recommended to identify chemical compounds present in these plants and testing different methods of extraction. Correspondingly, other solvents can be used for further investigation of microbial activity from these botanicals.


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