The mycelial growth of ten Diaporthe citri isolates was studied comparing six culture media (oatmeal-agar, malt-peptone-agar, potato-dextrose-agar, orange leaf-dextrose-agar, lemon leaf-dextrose-agar, corn-agar) under 22 ± 2 °C and 12 h light/12 h dark. The evaluation of the mycelial growth of the fungi was also compared under five different temperatures (10, 15, 20, 25 and 30 °C) and three different luminosity conditions (12 h light/12 h dark, continuous light and continuous dark) on potato-dextrose-agar media (PDA). Variations in pycnidial and mycelial mass production were observed in the different media, temperature and luminosity conditions tested. For most isolates, oatmeal-agar, 20-25 °C and continuous light promoted best sporulation. The pycnidial production was greater under continuous light. The pathogenicity test was made by inoculating mycelial discs of 5 mm on sores made in twigs and stem of citrus (Citrus spp.) cultivars. After seven days, gum exudation was observed in plants that were inoculated with the isolates, but not on control. All isolates were pathogenic, but PC2 and PC5 caused bigger lesions in plants.
