Fludioxonil and low temperature inhibit growth of Cladosporium cladosporioides isolated from sweet pepper postharvest

Cladosporium rot ( Cladosporium cladosporioides ) is a common disease affecting sweet pepper postharvest. Rots are frequently observed in Mediterranean growing regions, and conidia produced during refrigerated transport and storage can spread readily in air currents or by direct contact with healthy fruits. There are limited management strategies that are used to control Cladosporium rot that include protecting fruits from physiological disorders and limiting wounding. The objective of our research was to characterize C. cladosporioides isolates from sweet pepper in Israel and to determine isolate sensitivity to the fungicide fludioxonil. Isolates collected from multiple regions in Israel were slow growing and formed olivaceous-grey to brown colonies on PDA. The conidia measured 5.1 × 3.1 µm and ramoconidia measured 15.4 × 3.3 µm. The optimum temperature was 20 °C for mycelial growth and conidial germination, and limited fungal growth occurred at 1 and 30 °C. Fruit extracts enhanced conidial germination, while there was no effect of fruit surface exudates. In histological sections from diseased pepper, hyphae had ramified through the inner pericarp layer by 24 h post inoculation (hpi) and dissolution of the cytoplasm occurred by 72 h. Sporulation from the hyphal layer and diseased tissue was observed 96 hpi. On fludioxonil amended media the average EC 50 was 0.19 ppm for the isolates tested, suggesting this fungicide could be beneficial in disease management programs.