Eficácia dos extratos de romã no controlo de doenças pós-colheita em laranjas ‘Navelina’

Abstract

Efficacy of pomegranate extracts on controlling post-harvest diseases in ‘Navelina’ oranges Controlling post-harvest diseases through the use of plant protection products is becoming increasingly difficult, with strict limitations, loss of effectiveness and the public and markets demand for less or even residue-free products. As so, horticultural sector needs to effectively minimize post-harvest pathogenic fungal rot losses in citrus fruits with a reduced use of plant protection products. The literature indicates that different natural extracts, such as pomegranate skin extracts, have growth control properties of Penicillium digitatum. The objective of this work was to verify the effectiveness of pomegranate extracts in reducing postharvest losses of citrus fruits that Frutas Tereso markets, caused by the main postharvest pathogenic fungus P. digitatum. Water and methanol extracts of pomegranate skin from the varieties 'Acco' ‘Wonderful’ and 'Mollar de Elche' were obtained and secondary screening and semicommercial testing on 'Navelina' oranges were performed. In secondary screening in 'Navelina' oranges, treatment with aqueous extract of the 'Wonderful' pomegranate variety at a dry residue concentration of 1.2% versus control allowed a reduction in rot incidence of over 47% at day 7 and over 37% at day 10. With methanol solvent at a dry residue concentration of 2%, the reduction in the incidence of decay over the control was greater than 47% at days 7 and 10. In the semi-commercial trial, Wonderful-Methanol-2% treatment was the most effective: the reduction in incidence, sporulation and severity with this treatment was 33%, 44% and 40%, respectively. Tests indicate that pomegranate extract treatments, particularly 2% 'Wonderful' methanolic extracts, are effective in reducing the incidence, severity, and sporulation of P. digitatum rot in 'Navelina'.