Potential of Trichoderma sp. and Pinus sylvestris bark extracts as biocontrol agents against fungal pathogens residing in the Botryosphaeriales

Botryosphaeriales represents a diverse order of fungal pathogens of various woody plant species. In Serbia, these fungi are important pathogens of forest, ornamental and fruit trees causing die-back, cankers, leaf blights, fruit and root rot. The aim of this study was to evaluate the antifungal activity of Scots pine (Pinus sylvestris L.) bark extracts and Trichoderma sp. against Botryosphaeria dothidea, Neofusicoccum parvum and Dothiorella sarmentorum (Ascomycota: Botryosphaeriales) isolated from ornamental and forest trees. Bark extracts were prepared in water solution at two temperatures (80 and 120 ºC) and two pH levels (7 and 9). The extracts were tested using two concentrations (20 and 30%). Moreover, three isolates of Trichoderma sp. obtained from P. sylvestris bark were used against isolates of Botryosphaeriales and their antagonistic potential was estimated in vitro using a direct confrontation test. Mycelial growth of B. dothidea and D. sarmentorum in the presence of bark extracts was significantly inhibited while N. parvum showed no growth inhibition. B. dothidea growth was inhibited by 34 to 39% in case of 20% extracts and by 39 to 40% in case of 30% extracts. The growth inhibition of D. sarmentorum was between 48 to 60% in case of 20% extracts and 53 to 66% in case of 30% extracts.

All three isolates of Trichoderma sp. showed antifungal activity against selected pathogens. Isolate BK4G showed the highest inhibition level and it inhibited growth of B. dothidea, N. parvum and D. sarmentorum by 85, 62 and 75%, respectively.

Due to their ability to reside in wood, Botryosphaeriales are hard to manage. Moreover, environmentally safe pathogen control methods are preferred over classical fungicide treatments. This study suggested that both P. Sylvestris bark extracts and Trichoderma sp. could be used as biocontrol agents against Botryosphaeriales and that further evaluation of these agents in vivo is justified.