Assessment of the efficiency of essential oils of Ocimum gratissimum L. (Lamiaceae) and Hyptis suaveolens (L.) Poit. (Lamiaceae) in the biological control against sclerotinia of Abelmoschus esculentus (L.) Moench (Malvaceae) or okra (cultivars Volta and Hiré)
By: Doumbouya Mohamed, Tuo Seydou, Ouedraogo S. Leonard, Camara Brahima, Bolou BI Bolou Antoine, KouAkou Tanoh Hilaire, Koné Daouda
Key Words: Okra; Sclerotinia; essential oil; biological control; Côte d’Ivoire.
Int. J. Agr. Agri. Res. 8(3), 38-51, March 2016.
A study was conducted in order to determine the most sensitive cultivar of okra [Abelmoschus esculentus (L.) Moench], to fungus Sclerotium rolfsii Sacc. on the one hand, and on the other hand to compare the antifungal activity of two essential oils from Ocimum gratissimum L. and Hyptis suaveolens (L.) Poit., on this telluric mycopathogen from most vegetable crops grown in Côte d’Ivoire. Essential oils from dried leaves of these two plants were extracted by steam distillation for 3 hrs. The essential oil yield was very low with 0.29 % and 0.06 % respectively for O gratissimum. and H. suaveolens. The fungicidal properties of these essential oils were evaluated in vitro on the radial mycelial growth of S. rolfsii through five concentrations (125, 500, 1000, 2000 and 4000 ppm). After 7 days of incubation at 12-hour photoperiod at 25 ± 2 °C on PDA medium supplemented with essential oil, the radial mycelial growth of S. rolfsii was completely inhibited with 4000 ppm essential oils of O. gratissimum and H. suaveolens. The in vivo study showed a higher sensitivity of the Volta cultivar (83.33 %) to S. rolfsii than Hiré (16.67 %). The essential oils of O. gratissimum and H. suaveolens can be used in biological control against S. rolfsii, causal agent of Sclerotinia in okra crops. The Hiré cultivar is the best cultivar to be advised to farmers faced with this disease