Effect of nutrients and plant extracts on Alternaria blight of tomato caused by Alternaria Alternata

Studies with nutrients and phyto-extracts were performed in vitro and in vivo to assess their potential in controlling Alternaria blight of tomato (Solanum lycopersicum L., syn. = Lycopersicon esculentum Mill.) caused by Alternaria alternata. It has become a severe menace to the growers of Rajasthan in India and in general causes economic losses under changing climatic scenario. In the present study, seven nutritional elements (copper, calcium, zinc, magnesium, potassium, iron and boron) at 100, 300 and 500 ppm concentration and seven botanicals (Calotropis gigantea, Alstonia scholaris, Gingiber officinale, Allium sativum, Azadirachta indica, Datura stramonium and Aloe barbadensis) at 5, 10 and 15% concentrations were evaluated in vitro by poisoned food technique. In field experiments, further these nutrients (at 0.5% conc.) and plant extracts (at 10% conc.) were assessed by two foliar applications to control the disease. The results of in vitro studies with copper and zinc showed the most significant antifungal activity at all tested concentrations. In botanicals, the 100% inhibition of mycelial growth was obtained with garlic extract at 10% concentration. In field conditions, two foliar applications of copper sulphate (0.5%) were proved the most effective in reducing disease intensity (46.94%) and in increasing fruit yield (43.75%) followed by zinc sulphate. In plant extracts, garlic extract (10%) proved superior in reducing disease intensity (58.16%) and in increasing fruit yield (49.47%) followed by neem leaf extract. The results of this study indicate that foliar application garlic extract has great potential to be used to manage disease effectively and eco-friendly for the betterment of the end users. In lieu of consumer health, present findings may be helpful for growers to get extra benefits by producing organic tomato.