In vitro study of fungal endophythe as biocontrol agents against Sydowia polyspora, the cause of needle blight in Abies equi-trojani

In addition to its timber, the fir is an important tree that is produced in many parts of the world for landscaping and other uses such as Christmas trees. Current Season Needle Necrosis (CSNN) is one of the most important causes of drought in fir trees. The aim of this research is to investigate the efficacy of endophytic fungi against Sydowia polyspora, the causal agent of CSNN disease, in vitro and to contribute to future biological control studies. In this study, a total of 200 needle samples were taken from the non-symptomatic needles of Kazdağı fir (A. nordmanniana subsp. equi-trojani) trees in the Ilgaz forests within the borders of the Ankara Forest Management Directorate in 2023. Endophytic fungi were isolated from branch samples collected from 20 different trees in this region. Isolations were made for the detection of the causal fungus from some of the healthy needles taken from the needles showing CSNN symptoms. A total of 5 endophytic fungal species, S. polyspora (1 isolate), A. pullulans (1 isolate), T. rugulosus (1 isolate), Cladiosporium sp.(1 isolate), Penicillium sp. 1 (3 isolates), Penicillium sp. 2 (1 isolate), were isolated from the symptomless needles. Some of the isolated endophytic fungi; A. pullulans, T. rugulosus, Penicillium sp. 1, Penicillium sp. 2 isolates were cultivated and incubated against S. polyspora isolates by dual culture method. As a control, a sterile agar disc was placed opposite the S. polyspora isolates. Mycelial growth of control and endophytic fungi was measured on day 10 using a ruler and the inhibition percentage was determined using the inhibition percentage formula. The results showed that the endophytic fungi were effective against the causal fungus.