09-08-2013, 03:41 PM
In Vitro and field evaluation of different fungicides against early blight of tomato caused by Alternaria solani
ABSTRACT
Bio-assay of seven fungicides was done under in vitro conditions by using concentration of 250, 500, 750 and 1000 ppm against the early blight pathogen, A. solani by poisoned food technique and it was observed that all the fungicides significantly inhibited the mycelial growth even at all concentrations. Tebuconazole was most effective, recording no mycelial growth of the pathogenic fungus even at 250 ppm, followed by mancozeb, carbendazim + mancozeb, metalaxyl + mancozeb, copper oxychloride while carbendazim was least effective where maximum fungal growth was recorded at all concentrations (250, 500, 750 and 1000 ppm. When the rate of inhibition of fungal growth was compared over control, it was found that a maximum inhibition (100%) was observed in tebuconazole and minimum in carbendazim (44.81-55.19%). Field evaluation of various fungicides revealed that tebuconazole recorded the lowest disease intensity thereby indicating its usage in absence of any suitable variety followed by mancozeb, carbendazim + mancozeb, metalaxyl + mancozeb, captafol, copper oxychloride, whereas carbendazim should be least preferred. However, it was observed that there was no significant variation between tebuconazole and mancozeb during all the three sprays.