Fundecitrus identifies partial resistance of the black spot fungus to strobilurins

Fundecitrus has identified, for the first time in Brazil, evidence of partial resistance of the fungus Phyllosticta citricarpa, the causative agent of citrus black spot, to strobilurin fungicides. This finding corroborates alerts made by producers and technicians during the 2024/2025 crop season, in light of failures in controlling the disease in areas of the citrus belt of São Paulo. The study was conducted from the collection of samples of the fungus P. citricarpa in commercial orchards from different regions of the state of São Paulo. A total of 40 samples collected in the 2024/2025 crop season were analyzed, which were compared to other samples of the fungus sensitive to strobilurins collected between 1998 and 2012. According to Fundecitrus researcher Geraldo Silva Junior, strobilurins act on the respiration of fungi and the resistance of fungi to this chemical group of fungicides can occur through simple mutations in three different regions of the cytochrome b, in codons 129, ...