Growing apricots is not an easy task. The ideal climate for apricots is a uniform, moderately cold winter, mild dry spring and warm but not too hot summer. Apricot trees are the first of all fruit trees to bloom in the U.S. and bud kill is common in areas where cold spring temperatures drop below freezing. In addition to dangers of frost, apricot trees are also susceptible to several diseases that can cause brown spots to form on the fruit.
Shot Hole Disease
Shot hole disease may kill apricot buds during the winter and cause spots to appear on fruit and leaves in the spring. Spots caused by the fungus are light brown with dark purple edges and may flake off, leaving rough areas beneath. Shot hole disease lives on infected twigs that spread when splashed with water from a sprinkler or rain. Shot hole is similar to fog spot except the spots have red edges.
Bacterial canker disease mainly affects apricots and plums. This disease is capable of killing the entire tree within one or two years after planting. Cankers exude a sour smelling gum substance causing brown or tan spots on the bark, leaves and fruit. Spots on fruit appear as depressions with dark centers, sometime with underlying gum pockets.
Scab (also known as freckles) is the result of a fungus called Cladosporium carpophilum. This fungus is common throughout the midwest U.S. and affects peaches, nectarines, plums and apricots. This mild fungal disease is more common in low-lying shady areas where moisture evaporation is poor. Scab appears on fruit and twigs several weeks after the petals have fallen. Severely affected apricots will split open to the pit and never ripen, leaving fruit susceptible to brown rot.
Fungicide sprays are the easiest way to control fungal diseases that affect apricots. Spraying should occur from petal fall until 40 days before harvest, every 10 to 14 days. Other precautions include good soil drainage and removing nearby diseased plants and trees. Prune apricot trees every year to ensure good air circulation. New trees typically produce fruit during the third season; this is when they are most susceptible to scab. It is important to prune twigs with lesions during the first two growing seasons, according to the University of Illinois Extension.