Heat treatments effect on Cadophora luteo-olivacea of kiwifruit

Abstract Heat treatments represent alternative methods to fungicides to control latent fruit pathogens, such as Cadophora luteo-olivacea of kiwifruit. The study reports the efficacy of different hot water and hot air treatments (45 °, 50 °, 55 °, 65 °, and 70 °C with the duration respectively of 10, 15 and 20, 10, 65, 3 min) on the conidial and mycelial fungal isolates growth by in vitro assays. Both treatments at 70 °C were the most effective on the conidial and mycelial growth of C. luteo-olivacea isolates. On the mycelial growth, treatment efficacy was on average 88% and 71%, respectively, and on conidial growth by 100% and 91.3%. A significant reduction of xylanase and pectinase enzyme activities of the isolates was detected after hot water and air treatment (70 °C × 3 min). Both treatments showed, in most cases, the total reduction, sometimes variable with the target isolate. Hot air treatment was the most efficient treatment by reducing the skin pitting incidence in in vivo experiments, showing an efficacy of 46.6%, on average. Results show that heat treatments are effective against C. luteo-olivacea, but ‘time × temperature’ combinations remain the main challenge to develop.