Efficient control of conidium germination, mycelial growth and early blight in tomato in vitro with essential oils under farm conditions

The aim of this work was to find a natural product and efficient dose to control early blight in tomato crop in agro-ecological or conventional agriculture system. The treatments were essential oils from Cymbopogon citratus, Eucalyptus citriodora, Piper hispidinervum, Cymbopogon martini, Rosmarinus officinalis, Syzygium aromaticum, Cinnamomum zeylanicum, Mentha piperita, Citrus sinensis var. dulcis, and Melaleuca alternifolia used against Alternaria solani in Solanum lycopersicum under greenhouse conditions. In vitro, mycelial growth and conidia germination were completely inhibited by C. zeylanicum, C. martini, C. citratus, and S. aromaticum oils of 750 μL L-1, E. citriodora and M. alternifolia at 2000 μL L-1, and Mentha piperita in 5000 μL L-1. In tomato, plants under greenhouse conditions, early blight in leaf was inhibited by C. zeylanicum, C. martini, C. citratus, and S. aromaticum at 750 μL L-1, and E. citriodora oil of 5000 μL L-1. The best results for MIC 50 and 90 with minor dose to control was essential oil from C. citratus at 341.32 and 1.822.10 µL L-1 rich in geranial (46.91%), neral (34.34%), and geranyl acetate (6.30%). Therefore, it is possible to use this essential oils or manufacture a new and efficient product to control Alternaria solani in tomato plants.   Key words: Agroecology, Alternaria solani, Cimbopogon sp., Eucalyptus sp., Neral, Solanum lychopersicon.