Studies on the determination of soil-borne fungal pathogens in strawberry seedlings

The study was conducted in order to determine the precence and incidence of fungal pathogens in strawberry seedlings of Aydın Province, to identify them by conventional and molecular methods, and to determine the sensitivity of some strawberry cultivars to the most important pathogens found in the seedlings. Isolations were made from the crown and root of totally 2366 strawberry seedlings before plantings in the strawberry growing areas of Sultanhisar and Köşk during 2009-2010 and 2010-2011 cropping season. A total of 1014 isolates were obtained. Pathogenicity tests made by on stolons indicated that 291 Fusarium spp.,153 Rhizoctonia spp., 4 Macrophomina sp., and 9 Cylindrocarpon sp. isolates were pathogenic. Fusarium spp was found to be the major pathogen of the crown (the incidence 2,1% in first year and 1,1% in second year) and the incidence of Rhizoctonia spp. in the crown was 0,48% and 0,1%, respectively in both production seasons. The incidence of Fusarium spp was also the highest rate in the roots of seedling with 11,6% and 4,6% while the incidence of Rhizoctonia spp was 8,96% and 4,8%, respectively in two growing season. Pathogens were identified based on morphological features in conventional and molecular techniques. As a results of BLAST analysis of Tranlation Elongation Factor (TEF) 1α gene Fusarium oxysporum, , F.o. f.sp. fragariae, F. solani, F. arthrosporioides, F. verticilloides and F. proliferatum, F. acuminatum, F. avenaceum, F. redolens and F. lateritium were identified. Rhizoctonia isolates were also classified into two groups, multinucleate and binucleate by using nuclei staining technique. Molecular analaysis indicated that the 47,5% of binucleates belonged to AG-G, 18,6% to AG-A, 1,7% to both AG-A and AG-K, multinucleates belonged to 1,7% AG-4 anastomosis groups. Macrophomia phaseolina ve Neonectria (Ilyonectria) macrodidyma and Neonectria (Ilyonectria) radicicola were also determined from strawberry seedlings. In cultivar reaction studies performed in vitro on stolons showed that Fortuna, Rubygem, Camarosa and Festival were the most sensitive cultivars to F. oxysporum while Sabrina was tolerant. Fortuna and Camarosa were found to be more sensitive to Rhizoctonia spp., the cultivars of Sabrina, Rubygem and Festival were determined to be less sensitive. Keywords: Strawberry, seedling, Fusarium oxysporum f.sp. fragariae, Rhizoctonia spp., Neonectria spp. (Ilyonectria spp.), Macrophomina phaseolina.