Biocontrol strategies to reduce the impact of Septoria tritici blotch in wheat

Trichoderma strains are used as biofungicides for some plant diseases. The aim of this research was to evaluate the effectiveness of Trichoderma harzianum isolates, applied alone and in combination with fungicides, to control Zymoseptoria tritici, the causal agent of Septoria tritici blotch of wheat, and their impact on wheat yield and its components. To this end, field experiments were performed in 2010 and 2011 and 10 different treatments were applied. The disease severity was assessed by visual estimation of the leaf area affected by Z. tritici at the first node, anthesis and early dough growth stages. The best results for reducing the area under the disease progress curve (AUDPC) were “coated seed only with T. harzianum” and “coated seed plus two foliar application of T. harzianum”. Regarding the increase in yield gain and the improvement of yield components, the fungicide treatment applied at seedling, and tillering in 2011 provided significant increase. Respect the treatments with the application of T. harzianum the best was only one application as coated seed of the biocontroler alone showing yield responses similar to the ones obtained with the fungicide treatments. We recommended the coated seed alone because the protective effect lasts until the early dough stage of ripening. This application produced a comparable yield to that obtained with three applications of T. harzianum at different phenological stages of wheat with as well as with more than one application of commercial fungicide. We found a strong relationship between the number of kernels per spike and the wheat yield in 2011 as a consequence of the best environmental conditions for the disease’s occurrence. Contrary, it was shown a non-significant association between thousand kernel weight (TKW) and the wheat yield.