Brown rot on peaches and nectarines caused by Monilinia spp. results in significant economic losses in Europe. Experiments were conducted to study the effects of temperature (0-33 °C) on the temporal dynamics of decay and mycelium development and the subsequent sporulation on peaches and nectarine fruit infected by M. laxa and M. fructicola. The rates of decay and mycelium development increased with temperature from 0 °C to 25 °C for both Monilinia species. At 0 °C, decay was faster for M. laxa (0.20 cm days) than for M. fructicola (0.07 cm days); indeed, M. laxa was able to develop mycelia and sporodochia, but M. fructicola was not. At 4 and 20 °C, there were no differences in decay and mycelia development between the two Monilinia species. When temperature increased from 25 to 33 °C, the rates of fungal decay and mycelium development decreased. At 30 and 33 °C, M. fructicola decayed faster (0.94 and 1.2 cm days, respectively) than M. laxa (0.78 and 0.74 cm days, respectively) and could develop mycelia and produce sporodochia, whereas M. laxa failed at 33 °C. These results indicated that M. fructicola is better adapted to high temperatures, whereas M. laxa is better adapted to low temperatures. These results can be used to predict the relative importance of the two species during the season at a given site and to improve management strategies for brown rot in areas where both species are present.

No abstract

Monilinia spp. is the main pathogen responsible for postharvest losses of stone fruit.Several studies have examined the conditions for Monilinia spp. infection in the field, but very limited information is available about postharvest. Storing fruit for 24 hours in cold room and water dump fruit in a water tank are the most common handling operations during the postharvest of fruit. Then, the aim of this study was to investigate the risk of Monilinia fructicola infection for peaches and nectarines during cold storage and water dump operations. The storage of fruit with the presence of M. fructicola conidia on their surface for up to 30 days at 0 or 4 ºC and 98% Relative Humidity (RH), did not suppose an important risk of infection since only 3.3% of fruit were already infected. M. fructicola was not able to infect fruit at 20 ºC when the RH was around 60%, however, it was possible to develop disease if fruit was already infected before the treatment applications. Conidia of M. fructicola present on the surfaces of nectarines was not able to infect fruit stored at 0 ºC and 100% RH for 24 hours and then immersed in the water dump tank, nevertheless it was able to infect 26.3% of peaches in the same conditions. When fruit was immersed in the dump tank with water containing the presence of viable conidia of M. fructicola, and then fruit was incubated at 20 ºC and 60 or 100% for 7 days, the infection recorded was between 66.7 and 90%, respectively. In addition, water dump operation free from M. fructicola conidia favours optimal conditions to develop infections produced on fruit before the treatment applications. Therefore, postharvest water dump would provide optimal conditions to infect inoculated and non-inoculated fruit, increasing the need for water disinfection.

From all studied handling operations on stone fruit packing houses, hydrocooling is the most relevant in the development of brown rot disease. Duration of the treatment seems to be more important than chlorine concentration. In addition, hydrocooling and water dump were less relevant in peaches than in nectarines. As a general trend, hydrocooling and water dump reduced incidence on fruit with recent infections (2 or 24 h before operation); however, when infections have been established (48 h before operation) diseases were not reduced. © 2017 Society of Chemical Industry.

The survival of the fungus Monilinia fructicola on fruit and inert surfaces at different temperatures (range: 0–30°C) and relative humidity (RH) (range: 60–100%) was investigated. M. fructicola conidia survived better on fruit than on inert surfaces. The viability reduction rate at 20°C and 60% RH was 1.2 and 5.8 days−1 on fruit and inert surfaces, respectively. Overall, on fruit surfaces, conidia viability was reduced at high temperatures and was longer at higher RH than at lower RH; in contrast, on inert surfaces, conidia viability was longer at only low temperatures. On fruit surfaces, at 0°C and 100% RH, conidia survived up to 35 days, and at 30°C and 60% RH, conidia survived up to 7 days. However, on inert surfaces at 20°C and 30°C, conidia lost their viability after 48 and 24 h, respectively. These results suggest that M. fructicola can remain viable in cold rooms for over 30 days on fruit surfaces or over 25 days on inert surfaces. Furthermore, under the orchard conditions during the growing season, conidia may remain viable for only 2–3 days on immature fruit surfaces before conidia will be unable to penetrate the host.