Extracts, decoctions and essential oils of medicinal and aromatic plants in the inhibition of Colletotrichum gloeosporioides and Glomerella cingulata isolates from guava fruits

摘要

> size="2" face="Verdana, Arial, Helvetica, sans-serif">The main disease of the guava (Psidium guajava L.), after harvesting, is anthracnose, caused by Glomerella cingulata and Colletotrichum gloeosporioides. This pathogen and chemical residues of fungicides in fruits are considered the mains problems for exportation. In this work was evaluated the fungitoxic effect of extracts, decoctions and essential oils of medicinal and aromatic plants in the mycelium growth of the pathogens, in vitro, to be recommended as an alternative to chemical control in postharvest. To prepare the aquous extracts a 10% and the decoctions (sub-products of hydrodistillation) were added in PDA medium, autoclaved and distributed into Petri dishes. The essential oils were added in three equidistant points by Petri dishes contening PDA medium. Discs of the isolates of the pathogen were placed on the center of the Petri dishes. The fungitoxic effect was evaluated by measuring the diameter of the colonies when the pathogens or any other treatment reached the border of the Petri dishes. The aquous extract and the essential oil from the clove inhibit in 100% of G. cingulata and C. gloeosporioides growth, and the last one was totally inhibited by the essential oil of the lemon grass. The decoctions of rosemary, ginger, calendula, orange (Citrus sinensis) showed inhibition potencial to control both isolates of the pathogen. In the control of C. gloeosporioides also had good results the decoctions of mayweed, chamomile and tagetes. The total or partial mycelium growth inhibition of the Glomerella cingulata e Colletotrichum gloeosporioides showed the existence of compounds biologically actives with fungitoxic effect, in the extracts, decoctions and essential oils of medicinal and aromatic plants. This indicated a potential application of this products as an alternative to control anthracnose in guavas fruits.