Control of lemon postharvest diseases by low-toxicity salts combined with hydrogen peroxide and heat

•Lemon green and blue molds were controlled by H2O2 followed by low toxicity salts.•Phomopsis stem-end rot was controlled by sorbate and phosphite salts at 20 °C.•Either sorbate or a sequence of H2O2 and phosphite were the most promising treatments.•These treatments are proposed to control citrus postharvest pathogens.

The effectiveness of potassium sorbate, sodium bicarbonate and potassium phosphite combined with heat and hydrogen peroxide in the presence of CuSO4 to control major lemon postharvest diseases was investigated on artificially infected fruit. Green and blue molds, which both require wounds for infections to occur, were controlled by combination of hydrogen peroxide followed by inorganic salts, even when the temperature solutions were 25 °C. Control of sour rot was poor with salt solutions alone but significantly improved in treatments including hydrogen peroxide followed by potassium sorbate or sodium bicarbonate at 50 °C. Phomopsis stem-end rot was effectively controlled by potassium sorbate and potassium phosphite at 20 °C, and diplodia stem-end rot was partially controlled only by potassium sorbate. Applications of either potassium sorbate or a sequence of hydrogen peroxide followed by potassium phosphite were the most promising treatments, primarily because they controlled most of the diseases without the need to heat the solutions. These treatments controlled postharvest citrus diseases to useful levels and could be suitable alternative to conventional fungicides, or could be applied with them to improve their performance or to manage fungicide resistant isolates.