Abstract:

The aim of this study is to investigate the antifungal activity of propolis against V. dahliae Kleb. under both in vitro and in vivo conditions. Firstly, the inhibitory effect of the propolis on mycelial growth in Potato Dextrose Agar (PDA) media containing its ethanol extract (PE) at various concentrations (0.003, 0.06, 0.125, 0.25, 0.5, and 1 ppm/mL) was investigated under in vitro conditions. Then to assess the effect of PE on non-defoliating (PHCVd3 isolate) and defoliating (PHCVd47 isolate) pathotypes of V. dahliae, the varieties Giza 45 (resistant), Carmen (tolerant), and Acala SJ2 (susceptible) treated with PEE (1 ppm/mL) were observed in the plant growth chamber up to the 4-6 leaf stage. The whole in vitro experiments were carried out with three replicates, and the studies in vivo experiment were with five replicates depending on a completely randomized parcels design. The most effective dose of PEE with1 ppm/mL dose resulted in 75.2% suppression against the PHCVd3 isolate, while the effect of the same dose against the PHCVd47 isolate was 74.4%. The lowest disease severity index (DSI) values against PHCVd3 and PHCVd47 isolates in cotton cultivars treated with PE were 1.34 and 1.64 in the Giza 45, respectively, and the highest DSI values were 3.80 and 3.90 in the Acala SJ2 cultivar in vivo experiment, respectively. The findings indicate that PE treatment has a promising effect against cotton wilt disease that could be combined with known plant protection strategies.

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