Airborne dispersal in Rhizopus stolonifer mainly occurs through
Rhizopus stolonifer asexual reproduction relies on production of numerous haploid sporangiospores within spherical sporangium atop sporangiophore lifted above mycelium. Upon maturation sporangial wall ruptures due to dehydration, increased turgor and columella collapse releasing thousands of dry spores into air currents allowing distant colonization. Airborne dispersal allows colonization of fresh bread, fruits and dung across environments. Ascospores occur in sac fungi inside asci, basidiospores in club fungi on basidia, zoospores require water and motile flagella. Hence airborne spread in bread mold chiefly mediated by sporangiospores representing non-motile mitospores adapted for wind transport.
Ref: Campbell Biology 12th ed., Chapter 31: Rhizopus Sporangiospores Airborne Dispersal; NCERT Class 11 Sporangiospores; NCBI Mucor Dispersal