In Vitro Comparative Activities of Four Essential Oils on Mycelial Radial Growth of Magnaporthe Oryzae B.C. Couch, a Rice Blast Pathogen in Burkina Faso

Özet

Caused by Magnaporthe oryzae B.C. Couch, rice blast is considered as the main fungal disease in rice fields in Burkina Faso. Pure essential oils of Cymbopogon schoenanthus, Ocimum americanum, Ocimum gratissimum and Lippia multiflora were tested in vitro to assess the radial growth and inhibition rate of the fungus using the contact and fumigation methods. For each essential oil, five doses were developed: D2 (0.1 µl/ml), D4 (0.6 µl/ml), D6 (1.2 µl/ml), D8 (1.8 µl/ml) and D10 (2.4 µl/ml). In both tests, two synthetic fungicides namely mancozeb and azoxystrobin at recommended doses of 6.67 µl/ml and 3.33 µl/ml respectively, and an absolute control were used. The results showed that in the contact method, pure essential oils of O. americanum, L. multiflora, C. schoenanthus and O. gratissimum inhibited 100% of the mycelial radial growth of the fungus at doses D10 (2.4 µl/ml), D4 (0.6 µl/ml), D6 (1.2 µl/ml) and D4 (0.6 µl/ml) respectively. As for the fumigation method, oils of O. americanum, L. multiflora, C. schoenanthus and O. gratissimum inhibited mycelial radial growth of the fungus by 100% at doses D10 (2.4 µl/ml), D2 (0.3 µl/ml), D6 (1.2 µl/ml) and D8 (1.8 µl/ml) respectively. Mancozeb and azoxystrobin inhibited radial mycelial growth by 100% and 74.1% respectively. These essential oils can be used to control rice blast in the field. This will also reduce environmental pollution.