| Sumario: | The aim of this study was to establish the methodology and determine the relationships
between climatic factors and contamination of citrus fruit by the soil-inhabitant pathogenic
fungus Geotrichum citri-aurantii. This pathogen causes sour rot decay of citrus. The field trial
was set up in a ‘Murcott’ mandarin experimental orchard in Salto, Uruguay. Fruit sampling
was conducted weekly from March to June 2022. Six fruits from 2-3 trees per experimental
unit were arbitrarily selected within 50 cm from the orchard floor. Rainfall, air temperature,
wetness and relative humidity sensors were placed in the center of the orchard. Wind
sensors were placed at each sampling location. The mean number of epiphytic spores of G.
citri-aurantii per fruit (abundance) and the proportion of fruits positive for G. citri-aurantii
(incidence) were determined in the laboratory by washing and plating serial dilutions.
Climatic factors were related to G. citri-aurantii abundance or incidence through generalized
linear models specifying the normal or binomial error structure, respectively. For both
incidence and abundance, a significant negative relationship was observed with rainfall and
wind speed. In contrast, the relationship was significantly positive for wind gusts. The
variables wetness and maximum temperature were negatively and significantly related only
to abundance. Further field trials are necessary to validate the models and confirm the
results obtained in this first year of the study.
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