Losses in North Carolina from preharvest rots caused by C. acutatum are estimated at 1-5 percent while losses from postharvest decays are probably much higher on susceptible cultivars. Studies of fruit rot diseases conducted following storage or shipment of fruit show that this disease is the most damaging and most commonly occurring postharvest rot of blueberry. The pathogen causes sunken lesions on berries when infection occurs prior to harvest. Alternaria spores can be splashed or carried by wind-blown rain to other berries. This indicates that most alternaria infections are not initiated until after fruit is harvested, because the stem scar is only exposed when berries are detached.
Postharvest infections produce fuzzy mycelial growth on the surface of the berries.
This fruit rot disease was relatively unknown and of minor importance until the release of the cultivar Harrison. Although high yielding and large fruited, Harrison is extremely susceptible to phomopsis fruit rot and for this reason is no longer recommended for planting in commercial production fields. Spores from infected twigs are carried by rain to developing berries, where they infect and cause a soft rot at harvest. Prior to harvest, infected berries become light cream-color rather than normal blue and drop to the ground. These infected fruit, if left on the ground, form overwintering sclerotia and provide a source of inoculum the following year.