Inoculum sources and characterization of isolates of Gilbertella persicaria from peach fruit in South Carolina

In 1991 and 1992, Gilbertella persicaria was more common than Rhizopus spp. on rotted peaches found on the orchard floor in the major peach production areas of South Carolina. G. persicaria was isolated frequently from soil and surface organic debris in commercial peach orchards in five counties. Rhizopus spp, were isolated much less frequently from these sources. Also, G. persicaria was commonly found along with Rhizopus spp. in soil and debris collected from harvest bins before and during harvest, in hydrocooling water and dump tank water, and on packing line belts. Dicloran and iprodione were both active in vitro to inhibit growth of mycelium, but chlorinated water dips were required for control of fruit decay caused by G. persicaria. Selected isolates of G. persicaria grew and sporulated at 10 to 40 degrees C and induced symptoms within 4 days at 22 to 34 degrees C. External nutrients were required for spore germination, and wounding was required for infection of peach fruit.