Symptoms are small brown leaf spots, sometimes with characteristic tan centers and tiny black round structures (pycnidia) where the pathogen’s spores are produced. Tiny, dark brown spots (usually less than ¼ inch in diameter) also develop with bacterial leaf spot, therefore it is important to look for the diagnostic pycnidia in the spots to distinguish these diseases.
The pathogen’s spores are dispersed by water (rain and irrigation). Seed can be contaminated with this pathogen,
Do not work in crops when leaves are wet. Apply fungicides beginning at the start of disease development when symptoms have just started to appear. In commercial fields apply Quadris or Cabrio in alternation with Tilt on a 7-day schedule. Once introduced on a farm the pathogen causing Septoria leaf spot can survive in non-decomposed plant debris, therefore promptly incorporating debris after harvest and rotating land where parsley is grown are important management practices.