Influence of the temperature and relative humidity on the incidence of wheat leaf rust (Puccinia Triticina Eriks.) in southern Sonora, Mexico, during three crop seasons

The influence of climate upon a plant disease is a consequence of the causal agent and its interaction with the host plant. Plants present distinctive elements by the effect of climate, whether they are adverse or beneficial to their growth and development, as well as for their exposure or protection from those climatic factors. The objective of this work was to analyze the influence of temperature and relative humidity in relation to commercial wheat fields which presented leaf rust in different areas of the southern region of the state of Sonora, Mexico, during the crop seasons 2017-2018, 2018-2019, and 2019-2020. Weather data were recorded from 23 weather stations that belong to the automated weather station network of the state of Sonora which comprise the Yaqui and Mayo Valleys. A Voronoi diagram was constructed to delimit the region which corresponded to each weather station, and so to locate each of the commercial wheat fields with leaf rust incidence, in order to analyze the weeks in which disease incidence was high. A “t student test” of independent samples was performed in order to compare the weather variables (average, maximum and minimum temperature, as well as relative humidity) during the three crop seasons, from the weather stations where commercial wheat fields were detected with the presence of leaf rust, with respect to those where the disease was not present. Relative humidity was the main key factor for the presence of leaf rust, since it is the variable where the mean of groups with and without the presence of leaf rust, showed statistical significant difference in each crop season, unlike the average and the minimum temperature which showed difference only during the 2017-2018 crop season, and the maximum temperature during 2019-2020