In a review article published in this issue of Molecular Plant Pathology, Ceresini et al.(2019) wrongly treat the wheat blast fungus as a new species, Pyricularia graminis-tritici (Pygt), following the proposal of Castroagudin et al.(2016). Despite the host specificity implied by the name Pygt, the proposed species concept includes isolates that cause major disease epidemics on finger millet and turf grasses (Castroagudin et al., 2016, 2017). These authors also conclude, based on little evidence, that ‘the hypothesis of grass-specific populations for the overall Pyricularia oryzae species complex is falsified’. In addition, they stress that the rice blast fungus, which they describe as P. oryzae,‘may not provide a suitable model for understanding the biology of Pygt’. All of these conclusions are misinformed and have serious consequences. International quarantine regulations are needed to block the movement of this fearsome seed-borne blast fungus through the trade of seed or grain. The Pygt designation magnifies the challenge by grouping the dangerous, highly aggressive wheat pathogens from South America and Bangladesh, which are readily distinguishable from other P. oryzae lineages, with non-wheat pathogens that are already found worldwide and are not known to be virulent on wheat or rice. Careful biological analysis of wheat blast host–pathogen interactions has clearly shown that studies of other host-adapted forms of the fungus are relevant to an understanding of wheat blast and the development of new methods for disease control. Here, we summarize the overwhelming evidence that supports the alternative, internationally recognized designation of Pyricularia oryzae (synonym Magnaporthe oryzae; Zhang et al., 2016) as a single species divided into host-adapted lineages with limited primary host ranges. We also delineate the errors that led Ceresini et al.(2019) to their false conclusions. The same discussion applies to a second recently published review on the same topic (Ceresini et al., 2018).

Wheat blast disease is caused by a lineage of the ascomycetous fungus P. oryzae which is adapted to cause epidemics on hosts in the genus Triticum (Cruz and Valent, 2017; Islam et al., 2016; Urashima et al., 1993). This dangerous new disease emerged in Brazil in 1985 and subsequently spread to Bolivia, Paraguay and northern Argentina before moving to Bangladesh in 2016. This disease is poised to spread in South Asia and beyond, with major potential impacts for global food security. Pyricularia oryzae is best known as the causal agent of rice blast, which remains a major constraint on the production of rice (Oryza sativa) worldwide. In addition, P. oryzae causes