Identification of fungal diseases in Phalaenopsis orchid production and investigation of biological control possibilities

This study aimed to determine the fungal diseases that cause problems in Phalaenopsis orchids, which are grown as pots and cut flowers in the ornamental plant field in Türkiye, and to reduce the effectiveness of these factors by using biological control methods. In the study, isolation was made from plants showing disease symptoms from greenhouses in different provinces. As a result of the isolations, 11 fungal the species belonging to 5 genera were identified. The genus with the highest prevalence rate was Fusarium with 14- 64.4%, while the most common species isolated from all regions was F. oxysporum (F.o) with a prevalence rate of 6.5-16.3%. According to the isolation results, other identified genera and species are Pythium sp., Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, F. acutatum, F. chlamydoporum, F. poae, F. proliferatum, F. solani, F. redolens and F. verticilloides. In the study, Trichoderma spp. obtained by isolation of plant samples in order to evaluate biological control possibilities were discussed. T. harzianum, T. virens, T. koningii and T. atroviride were determined on species basis. T.harzianum was the most common species in all regions with a prevalence rate of 68.1%, while the least common species was T. atroviride with a prevalence rate of 2.2%. In pot trials, the orchid isolate of T. harzianum and its commercial preparation, reduced disease severity of F. oxysporum by 77.3% and 81.8%, respectively. Both treatments increased root length, root and shoot fresh weight in orchid plants compared to control and only-pathogen treatments.