GROWTH RATES OF RIPE ROT FUNGI AT DIFFERENT TEMPERATURES

Fruit storage and ripening studies have shown that the severity and incidence of ripe rots is affected by temperature and the ripeness of the fruit. High temperatures and long storage times favour the development of ripe rots while low temperatures and fast ripening times generally inhibit the growth of ripe rots. There is the potential for some fungi to grow faster or more slowly relative to one another depending on storage conditions. Differences in the growth rate at different temperatures of each type of fungi may explain, in part, why there are different incidences and severity of ripe rots in fruit from different orchards. To determine the growth rate of fungi, fungal isolates taken from ripe rots were grown in vitro on agar or in vivo on ripening fruit at a range of temperatures. Overall the fungi grew faster the warmer the temperature but each fungi species grew at different rates across the temperatures. The fungal growth on avocado flesh was exponential compared to a linear growth on agar suggesting it is not a good indication of the growth on avocado flesh. The growth of fungi could be linked to the rate of avocado flesh ripening, implying the riper the avocado flesh, the faster the fungal growth irrespective of temperature. In this study it was not possible to separately identify the effect of temperature or growth media on the fungal growth rates. Having prior knowledge of the predominant fungi in different lines of fruit could potentially aid in improving storage management