The Response of Tea Tree Oil as a Biofungicide Against Early Blight Disease in Tomato Crop (Solanum Lycopersicum) in Sudan

Abstract

The tomato crop (Lycopersicon esculentum Mill.) originated in Tropical Central and South America. In Sudan, tomato is gaining importance and its consumption has increased. It ranks as the second vegetable crop in Sudan. Tomatoes are subject to a large number of pests and diseases from the time of emergence to harvest. Among these; Early Blight is the most important fungal disease of tomato, induced by Alternaria spp. Current research is designed to investigate the potential of Early Blight biocontrol strategy through the use natural alternatives to pesticides with the aim of promoting sustainable agricultural development and economic growth. The antifungal effect of tea tree (Melaleuca alternifoilia) essential oil against Alternaria sp. was studied in vitro and in vivo. The inhibition effect of four different concentrations (0.5%, 1%, 2% & 3%) of tea tree oil or melaleuca oil on the growth rate (mm/hr.) of the pathogen was evaluated in potato dextrose agar. The inhibitory effect of the tea tree oil was examined in the nursery during 2007/2008 winter season using a susceptible open pollinated tomato cultivar Peto 86 and recommended fungicide for early blight disease of tomato Ridomil® Gold 72 W.P. for comparison. The results performed that the antifungal effect of tea tree oil against Alternaria spp. was enhanced significantly in vitro and in vivo with the least disease intensity of 12.50%.When tomato plants were treated with the concentration of 3% of the tea tree oil. Disease incidence of 17.88% and 25.08% was recorded on plants treated with the fungicide and the control treatment, respectively. Biocontrol methods based on inhibition of the spore germination of causal agents are achieving significant results. Some of the advantages of these methods over chemical methods include absence of residual toxicity, the harmlessness to the nature and costless.