Essential oil of clove (Syzygium aromaticum) to control Sclerotium rolfsii in vitro

Essential oils can inhibit growth of several phytopathogenic fungi of agricultural concern, such as Sclerotium spp. which causes root and collar rots, hampering the absorption of water and nutrients. Natural oils have short persistence in the environment and low toxicity, comprising compounds safer than conventional agrochemicals. Within the context of integrated management of diseases, essential oils may benefit the health of farmers, consumers and the environment. This study evaluated the in vitro inhibitory effect of clove (Syzygium aromaticum) essential oil on the mycelial growth of Sclerotium rolfsii. The experimental design was completely randomized, with 7 treatments (5 oil concentrations, 1 negative control, and 1 positive control) and five replications, with the experimental unit constituted by a Petri dish. The treatments consisted of different oil concentrations (0.0125; 0.025; 0.05; 0.1 and 0.2%) of clove essential oil, a negative control (0.0%) and a positive control, fungicide Tiram (1 mL L-1). The essential oil and the fungicide Tiram were merged into the synthetic Potato-Dextrose-Agar (PDA) culture medium. The plates were inoculated with the pathogen S. rolfsii and incubated for seven days at 25 ± 2 °C. We compared the treatments through the percentage of mycelial growth inhibition (PIC) and the mycelial growth velocity index (IVCM). Increasing oil concentration significantly reduced the mycelial growth of S. rolfsii and paralyzed mycelial growth at 0.1% concentration. The effect of clove essential oil was similar to the commercial fungicide