The brown rot fungus Monilinia fructicola (G. Wint.) Honey is economically the most important pathogen of peach (Prunus persica (L.) Batsch) in Georgia (30). Direct yield losses result from infection of flowers (blossom and twig blight) and from fruit rot at harvest and postharvest; indirect losses are due to the cost of fungicide application during bloom and during the pre-and postharvest periods. In most years, direct losses from M. fructicolaincited blossom blight are minor (23,32,33); however, cankers, formed on twigs as a result of blossom blight, may serve as a source of inoculum for infections that occur during the preharvest fruit ripening stage, particularly in early maturing cultivars (23,32,33). Other within-orchard inoculum sources for preharvest fruit infections include conidia produced on thinned fruit on the ground (1,9,17) and on aborted, nonabscised fruit in the tree (1,17). By contrast, conidia produced on overwintered fruit mummies in early spring do not survive long enough to cause fruit rot (24).Immature stone fruits generally do not exhibit symptoms or signs of infection by M. fructicola unless ingress and colonization are favored by prolonged rain or high humidity following injury. Even without wounding, however, immature fruit may harbor symptomless (latent) infections. Latent infections may become active as the fruit ripen, thus becoming a possible means of carryover of M. fructicola from the spring to the preharvest period. Latent infections by M. fructicola or the closely related M. laxa have been documented in apricot (25,28,29), peach (15,20,25), plum (21,25), prune (20), and cherry (8,31). Michailides et al. (19,20) reported positive relationships between the incidence of latent infection in immature French prune, nectarine, and plum and fruit rot severity at harvest and postharvest in California. Similarly, Northover and Cerkauskas (21) determined that latent infections in European plum in Ontario, Canada, occurred throughout the growing season and correlated positively with fruit rot incidence at harvest. These authors concluded that latent infections were most important in humid temperate regions, where they may readily progress to fruit rot.In peach, latent infections can occur during all stages of fruit development but their role in the epidemiology of brown rot is uncertain. Kable (13,15) concluded that only latent infections near harvest are important in the development of fruit rot in the semiarid climate of southeastern Australia. Landgraf and Zehr (17) surveyed potential inoculum sources for fruit infection by M. fructicola in South Carolina peach orchards but did not include latent infection. They did acknowledge, however, the need to evaluate the role of latent infection in the humid southeastern United States. A better understanding of the importance of latent infection in the epidemiology of brown rot could facilitate the early detection of increased fruit rot risk before harvest, thereby increasing lead time for disease management decisions (8,(18)(19)(20).The objectiv...