ABSTRACT
Aims: This work aimed at evaluating the effects of ethanolic and methanolic extracts of lemongrass upon the control in vitro of Colletotrichum gloeosporioides and upon the post-harvest quality of guavas “Paluma”. Methodology: We analyzed the inhibition of mycelial growth and sporulation of the pathogen at different concentrations of the extracts (8%; 5%; 3%; 1.5% and 0.5%). In the post-harvest assay, the guavas were treated by immersion in distilled water, ethanolic and methanolic extracts (1%; 0.5% and 0.25%) and stored at 25ºC ± 2ºC for eight days. We evaluated mass loss, total soluble solids, total titratable acidity, ratio, reducing and non-reducing sugars, ascorbic acid and pH and the incidence of anthracnose. Results: In the test in vitro, the pathogen growth inhibition was dose-dependent and the sporulation was completely inhibited upon higher concentrations of extract. At post-harvest, the fruits maintained their physicochemical characteristics, and the treatments were not efficient at retarding fruit ripening. Although the tested treatments inhibited the plant pathogen C. gloesporioides in vitro, they were not efficient at controlling the disease in vivo. Conclusion: The extracts showed control in vitro of C. gloeosporioides at 8%. However, the extracts were not effective at controlling the disease after harvest.
ABSTRACT
Aims: This study is aimed to evaluate the in vitro antifungal activity effect of the crude aqueous extract (CAE), hydrolate (HY) and essential oil (EO) of Corymbia citriodora, Cymbopogon citratus, Cymbopogon flexuosus and Curcuma longa against the phytopathogenic fungi Alternaria steviae, Botryosphaeria dothidea, Colletotrichum gloeosporioides and Sclerotium rolfsii, and assess, in situ, the effectiveness of CAE of medicinal plants in reducing the severity of the cucumber anthracnose. Methodology: The EOs and HYs were obtained by hydrodistillation. The CAEs were prepared by the turbolysis method. Mycelial growth of the fungi was measured daily, by the diametrically opposite method. In the in vivo test, the CAEs were sprayed on the cotyledon leaves of healthy cucumber plants with three days after were inoculated with C. lagenarium. The severity of assessment of the disease was based on a scale of notes. Results: The medicinal plants studied showed antifungal activity against all or almost all pathogens. In general, treatment with CAE and HY of C. longa revealed the highest inhibition against the fungi tested. With the exception of the EO of C. longa, the other EOs showed total inhibition against all the fungi and in all the concentrations tested. Compared to control, in in vivo assays CAE of C. citratus presents a potential for control of cucumber anthracnose reducing the severity of the disease. Conclusion: The medicinal plants studied produce compounds associated with antimicrobial activity.