SYMPTOMS AND SIGNS
Peacock spot appears on leaves as sooty blotches that develop into black, circular spots about 0.1 to 0.5 inch (2.5–12 mm) in diameter. There may be a yellow halo around the spot. Infection occurs in the fall, with temperatures between 35oF and 80oF. The optimum temperature is 58oF to 75oF. About 48 hours of free moisture allows the germinating spores to infect the leaf and cause significant disease. The warmer the temperature (up to about 75oF), the shorter the time necessary for infection to occur; it can be as little as 14 hours. The pathogen also infects fruit and fruit stems, but lesions are observed most often on upper leaf surfaces of leaves low in the tree canopy. Leaves fall prematurely. When significant defoliation occurs, strong bloom fails to develop and crop production is substantially reduced. Twig death may occur as a result of defoliation, and productivity is eventually further reduced.