Potassium phosphite in the management of green mold in citrus

Abstract

Orange is among the main produced species in citriculture, a widely important area of Brazilian agrobusiness. However, postharvest diseases, particularly the green mold caused by Penicillium digitatum, result insignificant losses in the sector. Given that chemical control is still the primary type of disease management, it is vital to create varied control methods to combine disease management programs. In this context, this study aimed to apply an alternative product based on potassium phosphite and evaluate its effect on the control of green mold and the quality of postharvest oranges.'Valencia' orange trees were treated with water (control), potassium phosphite (19.5 mL L-1), and benzimidazole fungicide (at the manufacturer's recommended dosage) at the first step of this work. The frequency and severity of green mold in the fruits were evaluated in the second step. The third step involved determining the physicochemical characteristics, which included peel and pulp color, pulp firmness, pH, titratable acidity, soluble solids, and ratio (SS/AT). Green mold incidence was reduced in oranges treated with fungicide and potassium phosphite, although the pathogen was not entirely inhibited. The effects of the potassium phosphite and fungicide treatments in oranges were similar in the area under the disease progress curve. The preharvest application of potassium phosphite (19.5 mL L-1) reduced the incidence of green mold in postharvest oranges without affecting the physical and chemical characteristics of the fruits, proving that the use of the alternative product can be a promising substitute.