Articles
Dry lenticel rot – an emerging postharvest disease on apples in northern Italy: insights from inoculation assays
Article number
1451_24
Pages
169 – 174
Language
English
Abstract
Ramularia mali, an emerging postharvest pathogen affecting apples, is causing concern due to the increasing number of cases since 2017. In contrast to the asymptomatic nature of the fungal infection in the field, symptoms on apples appear only after extended storage in cold storage facilities.
The initial occurrence of Ramularia spots, also known as dry lenticel rot, was observed in 2012 in the northern Italian region of Piedmont and the province of South Tyrol.
Recently, occurrence of the symptoms has been reported from other apple growing areas in Austria and France.
The aim of this study was to investigate the pathogen’s behaviour through inoculation assays, using three different methods (injection, puncture wounds, immersion) and subsequent storage for 3 months.
Two fungal isolates, one isolate originating from symptomatic fruit of the cultivar ‘Golden Delicious’, and one from the Ramularia mali type culture (CBS:129581), were used to inoculate apple batches at harvest time, as well as 5 and 7 months after harvest.
Symptom development occurred in 100% of the fruit when infected by injection of the conidial suspension.
Wounding of the apple cuticle by puncturing with a sterile needle showed symptoms in 94% of the apples after 7 months of postharvest storage.
However, no symptoms were observed in fruits at harvest time and after 5 months of storage.
Immersion of the fruit into conidial suspension showed no symptoms under all tested conditions.
The finding of a successful inoculation method is valuable for further research to improve the understanding of the dry lenticel rot symptoms’ development and pave the way for further investigations in the storage of apples.
The initial occurrence of Ramularia spots, also known as dry lenticel rot, was observed in 2012 in the northern Italian region of Piedmont and the province of South Tyrol.
Recently, occurrence of the symptoms has been reported from other apple growing areas in Austria and France.
The aim of this study was to investigate the pathogen’s behaviour through inoculation assays, using three different methods (injection, puncture wounds, immersion) and subsequent storage for 3 months.
Two fungal isolates, one isolate originating from symptomatic fruit of the cultivar ‘Golden Delicious’, and one from the Ramularia mali type culture (CBS:129581), were used to inoculate apple batches at harvest time, as well as 5 and 7 months after harvest.
Symptom development occurred in 100% of the fruit when infected by injection of the conidial suspension.
Wounding of the apple cuticle by puncturing with a sterile needle showed symptoms in 94% of the apples after 7 months of postharvest storage.
However, no symptoms were observed in fruits at harvest time and after 5 months of storage.
Immersion of the fruit into conidial suspension showed no symptoms under all tested conditions.
The finding of a successful inoculation method is valuable for further research to improve the understanding of the dry lenticel rot symptoms’ development and pave the way for further investigations in the storage of apples.
Authors
S. Primisser, D. Spadaro, S. Oettl
Keywords
Ramularia mali, apple pathogen, Koch’s postulates
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