Essential oils on the control of stem and ear rot in maize

Abstract

Stem and ear rot caused by Stenocarpella maydis are responsible for severe losses in maize production. Treatment of seeds with fungicides may induce environmental damage. Hence, this study aimed to evaluate the effects of essential oils extracted from Cymbopogon winterianus, Thymus vulgaris, Cymbopogon citratus, Corymbia citriodora, Cinnamomum zeylanicum, and Syzygium aromaticum on the development of in vitro S. maydis. In addition, maize seeds were treated with these essential oils to determine their possible mode of action and effects. The oils from S. aromaticum, C. zeylanicum, and T. vulgaris inhibited fungal development at concentrations higher than 0.025%. The oils from S. aromaticum and C. zeylanicum showed seed germination rates of 89.0% and 84.5%, which were higher than that of the control. The oils from S. aromaticum and C. zeylanicum reduced the pathogen incidence in the seeds to 39.0% and 28.0%, respectively. Further, these oils as well as that from T. vulgaris produced lower reduction of maize stand. Scanning electron microscopy examination revealed that essential oils from S. aromaticum and T. vulgaris acted directly on the conidia, impeding germination. The fi ndings suggest that the oils from S. aromaticum, C. zeylanicum, and T. vulgaris are potential alternatives for maize seed treatment in the control of S. maydis.