Spread of phytophthora rot on stored citrus and its prevention by fungicide dips 1

Oranges and lemons infected with Phytophthora citrophthora and P. syringae were placed among healthy fruits in boxes kept at 5, 10 and 14°C. The spread of the rot by contact infection was assessed after 3,6,12 and 18 days and again after 7 days' shelf‐life at 17°C. P. citrophthora infected adjacent fruits after 12 days at 10°C and 3 days at 14°C. No infection occurred at 5°C. P. syringue infected the fruits at all the temperatures tested. On fruits kept for 6 days at 5°C, the rot developed after shelf‐life. The presence of Phytophthora ‐infected fruits in orange and lemon packing boxes enhanced the development of penicillium rots. Post‐harvest dips in metalaxyl at 0.05 and 0.1% concentrations and fosetyl‐Al at 0.1,0.2 and 0.3% concentrations prevented the spread of P. citrophthora in packing boxes kept for 30,40 and 60 days at 11°C, but had no effect on penicillium rots. The mixture of the above fungicides with thiabendazole at 0.1%] or imazalil at 0.05%, concentrations gave best control against phytophthora and penicillium rots.