In vitro evaluation of plant extracts against early blight of tomato caused by Alternaria solan

Abstract

Early blight of tomato (Lycopersicon esculentum Mill) caused by Alternaria solani (Ellis & Martin Sorauer) is the most serious and destructive disease in worldwide. In the present study, ten plant extracts viz; Ashwagandha (Withania somnifera), Nithya Kalyani (Cathranthus roseus), Tulasi (Ocimum tenuiflorum), rhizome of Ginger (Zingiber officinale), bulbs of Garlic (Allium sativum), Coleus (Plectranthus scutelarioides), Bougainville (Bougainvillea glabura), Eruku (Calotropis gigantea), red and green coloured sea weeds were used against this disease. Experiment was laid out in Completely Randomized Design (CRD) with three replications by poisoned food technique. Mycelial growth of A. solani and percentage inhibition was recorded after 5, 7 and 9 days after incubation. All the tested plant extracts significantly inhibited the mycelial growth of the pathogen when compared with control. However, among all ten tested plant extracts ten percent of Garlic extract was found superior over other treatments followed by Bougainville, Eruku and Coleus by recording 77.4, 57.4 and 55.2 percent inhibition over control respectively. Least inhibition was observed in Ashwagandha (24.2%) and sea weeds (0%). Overall results revealed that all the tested concentrations of Garlic (Allium sativum) were found significantly effective against early blight of tomato.