Aqueous plant extracts for control of groundnut leaf spot in Burkina Faso
Early and late leaf spots, the two fungal diseases of groundnut (Arachis hypogaea L.) caused by Cercospora arachidicola Hori. and Phaeoisariopsis personata (Berk and Curt), respectively, cause severe groundnut crop losses in arid zone of West Africa. The objective of this study was to evaluate efficacy of aqueous extracts of four native plants species of Burkina (Lippia multiflora Moldenke, Boscia senegalensis (Pers.) Lam, Ziziphus mucronata Willd. and Securidaca longepedonculata L) against these diseases, on a susceptible groundnut variety (TS32-1) in the field during the cropping seasons of 2010 to 2012, in Gampela district in Burkina Faso. The four extracts (50 g dry weight per liter of distilled water) were sprayed by using a manual sprayer (Solo). Disease incidence and severity, defoliation rate, necrotic leaf area, pod yield, and 100 seed weight were evaluated. Disease score which attests to the severity of parasitic attack was done following ICRISAT’s disease score scale, which ranges from 1 to 9. Treatments with aqueous extracts of L. multiflora and Z. mucronata recorded the best disease control. The disease scores of these treatments were less or equal to 4 (corresponding to a resistance of plants), and increased pod yield by 2676.889 kg ha-1 (L. multiflora) and 2976.926 kg ha-1 (Z. mucronata), respectively. This field trial has confirmed that plants tested significantly control leaf spot diseases of groundnut.
Key Words: Arachis hypogaea, Cercospora arachidicola, Phaeoisariopsis personata