Antifungal activity of Cosmos caudatus extracts against seven economically important plant pathogens
2013
Salehan, N.M. (University Putra Malaysia, Selangor (Malaysia). Inst. of Tropical Agriculture) | Meon, S. (Universiti Putra Malaysia, Selangor (Malaysia). Dept. of Plant Protection) | Ismail, I.S. (Universiti Putra Malaysia, Selangor (Malaysia). Inst. of Bioscience)
Crude leaf extract of Cosmos caudatus Kunth was separated into hexane, ethyl acetate and aqueous fractions and screened for antifungal activity against selected plant pathogens using agar cup method. The ethyl acetate (EtOAc) fraction was the most active in inhibiting growth and spore germination of Phytophthora palmivora (Butl.) Butl., the causal pathogen of black pod of cocoa, with percentage inhibition in radial growth (PIRG) of 52%. Sporangial germination was recorded to be the lowest in the EtOAc fraction with value of 15.62%. Scanning electron microscopy of P. palmivora treated with the EtOAc fraction showed stunted growth and abnormalities in the mycelium with reduced spore production. The bioefficacy of the fractions was further tested on detached cocoa pods. The EtOAc fraction gave the highest inhibition of 57.46% on diameter of lesions. These findings indicate that the ethyl acetate fraction of C. caudatus contains antifungal agents effective against P. palmivora, which could be used in the development of biopesticide for the control of black pod disease.
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