Ecological behavior of Drechslera/Helminthosporium spores in a wheat crop in NW Spain

The objective of this study was to determine the presence of Drechslera/Helminthosporium in the air of a wheat crop in the NW Iberian Peninsula and its relationship with meteorological variables. Research was conducted in A Limia, Ourense, during the wheat growing seasons from 2021 to 2023. The Lanzoni VPPS-2010 spore trap was used to collect the spores, which were identified by optical microscopy. The phenological stages of the wheat crop were classified according to the BBCH scale, and the spore concentrations in each phenophase were analyzed. Meteorological variables were provided by a meteorological station located near the spore trap. In 2021, monitoring was done for 94 days, in 2022 for 89 days and in 2023 for 78 days. Spores were detected during most phenological stages, mainly during 11–20 h. Temperature and sunshine hours were the variables that positively influenced the variations in Drechslera/Helminthosporium concentrations in the air in 2021 and 2023, while in 2022, relative humidity, rainfall and leaf moisture were the factors that had the most influence. The maximum temperature and leaf moisture of the previous days were the variables that best predicted the concentrations of these spores for 2022. This is the first investigation in Spain that reports the presence of the sporal type Drechslera/Helminthosporium in the air during all phenological stages of wheat cultivation, and provides useful information for the development of strategies to prevent the diseases they cause.