Anthracnose can be identified by examining the fruit with a microscope for appressoria or infection pads produced by fungus. Anthracnose tearstaining can occur when Septoria spot is also a problem. The fungus, Septoria spp. Complete coverage is important, repeated applications may be necessary for season long control, especially following heavy rainfall. It occurs in the San Joaquin Valley and interior districts of Southern California during cool, moist weather.
Infections begin when spores of the fungus are spread throughout the tree in dew or rain water.
The damage to the rind lowers the grade of the fruit and results in culling. Septoria spot may be confused with copper injury, except that the pits caused by copper do not have fungal fruiting bodies. A tearstaining often accompanies the spotting. On lemon, the small spots develop into large, brown blotches during storage. Septoria may cause similar spotting on leaves or twigs that are weakened by frost or pests.