Aerial transmission of Thielaviopsis basicola, a pathogen of corn-salad, by adult shore flies

Chlamydospores of Thielaviopsis basicola were consistently observed in fras s excreted by adults and larvae of shore flies that were collected in the i mmediate vicinity of naturally infected corn-salad plants obtained from a c ommercial greenhouse production facility. Approximately 95% of the adult fl ies and 85% of the larvae were internally infested with the pathogen. Patho gen-free adult shore flies were subsequently shown to acquire the pathogen by ingestion after feeding on naturally infected plants. Viable propagules of the pathogen were excreted by these internally infested adults and were capable of transmitting the pathogen to healthy seedlings, which subsequent ly became infected.