Studies on the interaction between Septoria tritici and Stagonospora nodorum in wheat

Interactions between Stagonospora nodorum and Septoria tritici were studied . Results from a detached glume experiment indicated that the interaction m ay be isolate-dependent, as it was shown that the interaction between the t wo pathogens may be beneficial or antagonistic depending on the isolate of each pathogen present. The number of spores produced by both pathogens was significantly greater when an aggressive isolate of S. tritici was mixed wi th a non-aggressive isolate of S. nodorum, whereas the number of spores pro duced by both pathogens was significantly less when two non-aggressive isol ates were mixed. There was a significant reduction in disease level when S. tritici was applied prior to S. nodorum, compared to vice versa in the gro wth chamber. Results from growth chamber and field studies showed that S. n odorum produced significantly more spores when both pathogens were present together. It is concluded that S. tritici has a stimulatory effect on spore production by S. nodorum. However, there was a reduction of S. tritici spo res observed in the dual inoculation treatments, suggesting that S. nodorum inhibits S. tritici.