IN VITRO EVALUATION OF PLANT EXTRACTS AGAINST FOLIAR FUNGAL PATHOGENS INDUCING GROUNDNUT (Arachis hypogaea L.) LEAF SPOTS

Abstract

In 2024, an invitro experiment was conducted to evaluate the efficacy of two plant extracts, Azadirachta indica (neem) seeds and Eucalyptus cameldulensis (eucalyptus) leaf against three foliar fungal pathogens Puccinia arachidis Speg., Cercospora arachidicola Hori and Phaeoisariopsis personata Berk. causing rust, early and late leaf spots respectively, on groundnut (Arachis hypogaea L.) in Crop Protection Department, Institute for Agricultural Research (IAR) Zaria. The treatments consisted of a factorial combination of the three pathogens, two plant extracts in three different concentrations (0.5, 1.0 and 1.5 mg/ml), a standard check of mancozeb + carbendazim (Team®) used at recommended rate (2 kg/ha) and an untreated control, making a total of twenty-four (24) treatments with four replications, in a completely randomized design (CRD). Data were collected on radial mycelial growth taken daily starting at second day after inoculation (DAI) for seven days and spore count at 14 DAI. The results showed that neem seed and eucalyptus leaf extracts, at 1.0 and 1.5 mg/ml, significantly inhibited radial mycelial growth and sporulation of Cercospora arachidicola, Phaeoisariopsis personata and Puccinia arachidis, with neem seed extract demonstrated higher inhibitory activity compared to eucalyptus leaf extract. This finding suggests neem seed and eucalyptus leaf extracts at 1.0 and 1.5 mg/ml will be viable alternatives to synthetic pesticides for managing groundnut foliar fungal pathogens in-vitro.