Corn bacterial leaf streak: alternative hosts of Xanthomonas vasicola pv. vasculorum

ABSTRACT Corn bacterial leaf streak is an emerging disease, and there are few studies related to its management. Therefore, it is necessary to know alternative hosts of this pathogen that may interfere with its survival during the off-season. The aim of this work was to evaluate different genotypes of oats, barley, and wheat as secondary hosts to the pathogen Xanthomonas vasicola pv. vasculorum. The experiments were carried out in Guarapuava, PR, Brazil, in the 2019 and 2022 seasons, in a greenhouse, with completely randomized design and five replications. Eight different cultivars of winter cereals widespread in the region were inoculated, and susceptible corn hybrid was used as a control. Disease incidence evaluations were performed to calculate the area under the disease progress curve (AUDPC). In the 2019 season, relative humidity averages at ten days after inoculation were between 54 and 68%, and only TBIO Audaz wheat cultivar, in addition to the control, showed symptoms related to the disease. In the 2022 season, when relative humidity remained around 70% throughout the experiment, all genotypes tested showed symptoms. However, cultivars Danielle (barley), TBIO Audaz, and ORS Vintecinco (wheat) did not differ from the susceptible corn control, with the highest AUDPC values. These results indicated that winter cereals are hosts of X. vasicola pv. vasculorum, and that relative humidity affects the expression of disease symptoms.