Interaction between Diplodia pinea or Diplodia scrobiculata and fungal endophytes isolated from pine shoots

Abstract

Four endophytes isolated from healthy shoots of adult red pine ( Pinus resinosa Aiton) or jack pine ( Pinus banksiana Lamb.) trees were tested as potential biocontrol agents of the conifer shoot blight and canker pathogens Diplodia pinea (Desmaz.) J. Kickx fil. and Diplodia scrobiculata J. de Wet, B. Slippers & M.J. Wingfield. The effect of the endophytes on the germination of Diplodia species conidia and on the symptom severity caused by these pathogens on P. banksiana seedlings under greenhouse conditions was evaluated. Aggressiveness of each organism also was determined by means of single inoculations on jack pine seedlings. The results indicated that the endophyte Trichoderma atroviride P. Karst. showed a clear antagonism to Diplodia species. The culture filtrate of this fungus was able to reduce spore germination of D. scrobiculata. Furthermore, it was able to inhibit the D. pinea invasion when both organisms were inoculated in the same seedling. The observed reduction in the symptom severity on jack pine seedlings might be due to parasitism and (or) production of inhibitory compounds. Therefore, T. atroviride might deserve further investigations for its use as biocontrol agent against D. pinea.