Wheat blast caused byMagnaporthe oryzaepathovarTriticumis efficiently controlled by the plant defence inducer isotianil

Wheat blast caused byMagnaporthe oryzaepv.Triticumis an upcoming threat to wheat cultivation worldwide. The disease crossing over to wheat first gained attention in South America, with increasing interest coming from its more recent appearance in the big wheat-growing areas of Asia. The increasing economic relevance of the disease and the lack of genetic resistance in current wheat breeding material, besides fungicide resistance already present in fungal pathogen populations, highlighted the need to evaluate the potential of isotianil as an alternative plant protection measure. Isotianil is already registered in Asia for the protection of rice againstM. oryzae, but because the agronomic practices and disease development of blast differ between rice and wheat, the efficacy of isotianil against wheat blast was hard to predict. Testing isotianil in the currently available formulations, applied either as seed treatment or soil drench, resulted in a significant reduction of disease severity. The efficacy was comparably high, on different wheat cultivars and using several fungal isolates with different degrees of virulence. Microscopic analyses revealed that isotianil treatment can prevent invasive growth of the pathogen. No phytotoxicity from isotianil treatment was observed on wheat plants. Importantly, isotianil not only protects wheat plants at the seedling stage but also on spikes thereby preventing losses due to this most severe disease syndrome. In summary, the results showed the high potential of isotianil to protect against wheat blast.

Automated summary

Isotianil showed significant efficacy in reducing disease severity of wheat blast when applied as seed treatment or soil drench, with microscopic analyses revealing its ability to prevent invasive growth of the pathogen. The results demonstrated the high potential of isotianil to protect wheat plants against wheat blast, and no phytotoxicity was observed on wheat plants following treatment.