Significance of Gnomoniopsis smithogilvyi as kernel rot of sweet chestnut in Turkey

Abstract

AbstractChestnut nut rots caused by fungi, especially by Gnomoniopsis smithogilvyi, showed a significant increase not only in Turkey but also in the other chestnut‐producing countries. In this study, the prevalence of chestnut kernel rot was determined by using 800 fruits collected from eight significant chestnut‐growing provinces of Turkey located in the Black Sea, Marmara, and Aegean Regions. Six types of kernel rot symptoms were determined from the necrotic nuts, brown rot being the most common accounting for 62% of the necrotic nuts. Along with G. smithogilvyi, seven additional fungal species Colletotrichum fioriniae, C. godetiae, Cryphonectria parasitica, Diplodina agrifoliae, Fusarium concentricum, Fusarium tricinctum, and Trichothecium roseum were found to be associated with kernel rot. In addition, some other ubiquitous fungi such as Penicillium spp. were detected. All the pathogenic fungi were identified through a combination of morphological traits and phylogenetic analysis involving partial internal transcribed spacer (ITS) sequences, as well as tef1 and tub2 loci sequences. The most frequently isolated fungus was G. smithogilvyi, and it was found at 98, 31, 10, and 1 of the necrotic kernels out of 291 showing brown rot, brown to black rot, cream colour decay, and white rot symptoms, respectively. It was not found from the kernels showing green rot and greenly‐blue rot symptoms. G. smithogilvyi was prevalent in six of eight chestnut‐growing locations in Turkey. Based on the findings, G. smithogilvyi was shown to be the main fungal agent of brown kernel rot of chestnuts, and some of the other fungi obtained from the kernels were shown to contribute kernel rots of chestnuts.