Characterization of root rot disease of kiwifruit in the Black Sea region of Turkey

Forty-two kiwifruit orchards from Rize and Samsun provinces (Black Sea region, Turkey) exhibiting symptoms of root rot disease were examined between 2009 and 2010. Twenty-four fungal isolates recovered from affected roots were included in this study. Morphological characteristics of all isolates were recorded on potato dextrose agar, malt extract agar and Spezieller Nahrstoffarmer agar. The effect of temperature on radial colony growth was also evaluated at 5, 10, 15, 20, 25, 30, and 35 A degrees C. Histone H3 gene (HIS) was amplified with primers CYLH3F and CYLH3R and the amplified fragments were sequenced. The HIS phylogeny grouped all the isolates into six well-supported clades which were in agreement with phenotypical characteristics. Isolates were identified as Cylindrocarpon pauciseptatum, Cylindrocladiella parva, Ilyonectria liriodendri, I. torresensis, I. robusta and I. europaea, I. liriodendri being the most frequent species. All of them are reported for the first time on kiwifruit in Turkey, with the exception of I. liriodendri. Pathogenicity tests with selected isolates showed that 10 out of 11 isolates tested were able to induce typical root rot disease symptoms, affecting plant development and leading to the death of some plants. This study shows the high diversity of root rot pathogens found in kiwifruit trees in the Black Sea region of Turkey, being the first step towards a better understanding and management of the disease in local conditions.