Bio-efficacy of fungicides, bioagents and plant extracts/ botanicals against Alternaria carthami, the causal agent of Alternaria blight of Safflower (Carthamus tinctorius L.)

A total of eleven fungicides namely: mancozeb 75 WP, chlorothalonil 75 WP, copper oxychloride 50 WP, thiram 75 WP, captan 50 WP, difenconazole 25 EC, carbendazim 50 WP, hexaconazole 5 EC, propiconazole 25 EC, penconazole 10 EC and metalyxil + mancozeb (Ridomil) 68 WP were evaluated (at 500, 1000 and 1500 ppm each) in vitro against Alternaria carthami. All the fungicides tested caused significant inhibition at all three concentrations tested over untreated control. The average inhibition recorded with the test fungicides was ranged from 28.39% (chlorothalonil) to 94.44% (carbendazim). However, carbendazim recorded significantly highest average mycelial growth inhibition (94.44%). The second and third best fungicides found were mancozeb (85.43%) and thiram (83.33%). These were followed by hexaconazole (82.95%), ridomil (82.83%) and difenconazole (77.16%). All the six fungal and one bacterial bioagents/antagonists evaluated in vitro were found antifungal/antagonistic against A. carthami. However, T. viride was found most effective and recorded significantly highest mycelial growth inhibition (94.07%) of the test pathogen over untreated control. The second and third best bioagents/antagonists found were T. hamatum and T. koningii which recorded mycelial growth inhibition 85.18 and 81.11%, respectively. All the eleven plant extract/botanicals were evaluated in vitro (each at 10, 15 and 20%) against A. carthami. The mean percentage mycelial growth inhibition recorded with all the test botanicals was ranged from 19.26 (A. racemosus) to 62.47 (A. sativum) per cent. However, A. sativum was found most fungistatic which recorded significantly highest mean mycelial growth inhibition (62.47%). The second and third best botanicals found were D. metal (49.87%) and C. longa (46.91%). Thus, all the botanicals tested were found fungistatic antifungal and caused significant inhibition of A. carthami over untreated control.   Key words: Alternaria carthami, in vitro, fungicides, botanicals, bioagents, inhibition.