In-vitro evaluation of fungicides, bioagents and aqueous leaf extracts against Alternaria leaf blight of cotton

All the six fungicides viz.,Mancozeb (75% WP); Carbendazim(50WP), Copper oxychloride (50WP), Captan (50 WP), Thiram (75 %WP), Chlorothalonil (75 WP) evaluated in vitro (@500, 1000 and 1500ppm) were found effective against A. macrospora and causedsignificant inhibition of test pathogen over untreated control.However, Thiram was found most effective and recorded significantlyhighest mean mycelial inhibition (90.42%). This was followed by thefungicides, Captan (82.04%), Mancozeb (79.88%),Carbendazim(77.5%), Chlorothalonil (74.52%) and copper oxychloride(71.75%). All the five fungal and one bacterial bioagents/ antagonistsevaluated in vitro against A. macrospora were found antifungal/antagonistic against the test pathogen. However, T. viride was foundmost effective and recorded least linear mycelial growth (32.72 mm)with corresponding significantly highest mycelial inhibition (63.64%)of the test pathogen. The second and third best bioagents foundwere T. koningii and P. fluorescens, which recorded linear mycelialgrowth, respectively of 33.90 mm and 33.95 mm with correspondingmycelial inhibition, respectively of 62.33 and 62.27 per cent. All thesix botanicals/plant extracts evaluated in vitro (@5, 10 and 15 %each) were found fungistatic/ fungicidal against. A.macrospora.However, significantly least mean radial mycelial growth (56.18mm)and significantly highest mean mycelial inhibition (37.47%) wasrecorded with Garlic. The second and third best botanicals foundwere onion and Tulsi which recorded second and third least meanradial mycelial growth, respectively of 58.52 mm and 62.51 mm with corresponding mean mycelial inhibition of 34.97 and 32.86 percent, respectively.

In-vitro evaluation of fungicides, bioagents and aqueous leaf extracts against Alternaria leaf blight of cotton Keywords:

Gossypium spp. , Alternaria macrospora , Fungicide , Bioagents , Aqueous leaf extracts , Mycelial inhibition ,