In Vitro Evaluation of Fungicides, Botanicals and Bioagents against Alternaria alternata, Causing Leaf Spot of Gerbera

Gerbera (Gerbera jamesonii Hook), one of the important flower crops suffers from substantial damage with leaf spot disease incited by Alternaria alternata (Fries) Kessler. Results of the in vitro evaluation revealed that all the test fungicides, botanicals and bioagents significantly inhibited mycelial growth of A. alternata, over untreated control. Of the systemic fungicides tested, highest average mycelial growth inhibition was recorded with Hexaconazole (94.44%), followed by Carbendazim (84.93%), Propiconazole (81.53%), Difenconazole (75.97%) and Thiophanate methyl (51.21%). Of the non- systemic fungicides tested, Mancozeb recorded highest average mycelial growth inhibition (92.21%), followed by Curzet (84.45%), Chlorothalonil (80.90%), Propineb (78.89%) and Copper oxychloride (74.03%). Aqueous extracts of all the botanicals tested (@ 10 and 20%) were antifungal to the test pathogen. However, significantly highest average mycelial growth inhibition was recorded with A. sativum (74.45%), followed by C. longa (63.99%), D. metal (53.06%), C. gigantica (48.99%) and P. hysterophorus (48.90%). Among the bioagents tested, significantly highest mycelial growth inhibition was recorded with T. vride (86.67%), followed by T. hamatum (78.34%), T. koningii (76.67%), T. lignorun (68.15%), T. harzianum (53.16%) and Pseudomonas fluorescens (50.38%).