Fungicidal Action of Coconut Waste Liquid-Smoke on Citrus Fruit-Rot Pathogens (<i>Penicillium digitatum</i> and <i>Penicillium italicum</i>)

Abstract

The purpose of this study was to determine the fungicidal action of liquid smoke generated from young coconut waste for infection of green rot (Penicillium digitatum) and blue rot (Penicillium italicum) pathogens in postharvest citrus fruit. The pyrolysis of 1 kg of young-coconut resulted in 409 mL of crude liquid smoke, and 300 mL of distilled liquid smoke. The resulting distilled liquid smoke has the following characteristics: brownish-yellow in color, pH of 2, specific density of 1.02 g. mL -1 , and a total acid content of 10.7. Liquid smoke produced from young coconut waste was of good quality, in accordance with international quality standards. The overall characteristics of liquid smoke from coconut waste meet international liquid smoke standards, which include specific gravity, color, acidity, and pH in the required range and the absence of dispersed substances. The results showed that in in vitro testing, liquid smoke treatment at a concentration of 2.5% was able to retard the mycelium of Penicillium digitatum and Penicillium italicum with 100% inhibition. Whereas in in vivo testing, liquid smoke treatment at a concentration of 75% was able to retard the increase in the lesion diameter of the P. italicum fungal infection by 76.1%. However, all concentrations of liquid smoke treatments had no effect on P. digitatum. Treatment of the concentration of liquid smoke had no effect on the lesion diameter of the green rot infection on citrus fruit. Whereas in blue rot disease, the concentration of 50, 75, and 100% liquid smoke treatment gave different lesion diameter compared to the control, but among the treatments there was no difference in the lesion diameter. This proved that the treatment of liquid smoke concentration of 50% was established to have fungicidal action against blue rot desease on citrus fruit.