Investigation of the Phytopathological Causes of Citrus Tree Trunk Foaming in Turkey

Foaming was observed in mandarin and orange species that were grafted on rootstocks trifoliata ( Poncirus trifoliata ) hybrids and was investigated in terms of phytopathological causes in the Cukurova region, where 80% of Turkey's citrus production takes place. Citrus exocortis viroid (CEVd) and citrus cachexia viroid (CCaVd) agents were screened by RT-PCR method by taking samples from different citrus rootstocks and cultivars showing foamy bark symptoms. It was determined that 17 of the 49 isolates were infected with CEVd and 14 of them were infected with CCaVd. There are 4 trees infected by both viroid agents at the same time. Based on a blast analysis, it was found that the reference genomes for CEVd and CCaVd in the NCBI GenBank had 95-100%. To check on the presence of bacterial and fungal agents, isolates were created from the foamy bark tissue of citrus trees . Lasiodiplodia theobromae , Ilyonectria liriodendri , Fusarium pseudonygamai , Alternaria alternata , and Streptomyces spp . were found as a result of the isolations. Analysis of soil samples taken from citrus plantations that had indications of foamy bark revealed a high calcareous soil structure with a pH above 7.5. Keywords: Citrus, Foamy bark, Viroids, Cukurova region, Turkey DOI: 10.7176/JBAH/13-18-04 Publication date: October 31 st 2023