Chemical composition and antifungal activity of mandarin essential oils on the in vitro control of Colletotrichum abscissum

Abstract

Citrus farming in Brazil faces phytosanitary problems, especially postbloom fruit drop, caused by the Colletotrichum abscissum fungus. This study investigated the action of mandarin essential oils on the in vitro development of C. abscissum. Essential oils of IAC 2019Maria mandarin, Murcott IAC 221 tangor, and Late IAC 585 willowleaf mandarin were analyzed, extracted from immature and ripe fruits at different dosages (0, 2, 4, 8, 16, and 32 µL mL-1), as well as the main chemical components found on them, and the in vitro inhibition of mycelial growth, sporulation, and spore germination of the fungus. Limonene was the main compound found for all mandarin varieties at both ripening stages. The essential oil from immature fruits of Late IAC 585 showed a greater mycelial growth inhibition (66.89 %), whereas that from ripe IAC 2019Maria mandarin fruits stood out with greater inhibition (67.24 %). Both essential oils from immature fruits controlled sporulation; but, for ripe fruits, only the dosages influenced the conidia reduction. The dosages of 16 and 32 μL mL-1 of the essential oils extracted from immature and ripe fruits of the three mandarin varieties inhibited spore germination, indicating a potential alternative strategy for disease management.

KEYWORDS: Citrus farming, postbloom fruit drop, limonene.