AbstractMany growers on mushroom farms producing white and brown varieties of Agaricus bisporus have noticed a potential association between sciarid fly (Lycoriella ingenua) pest populations and green mold (Trichoderma aggressivum) disease expression, and suspect that in addition to other preventative measures, controlling flies may be important to controlling green mold spread. In this study, we examined the association between L. ingenua populations and green mold disease incidence in commercial mushroom farms. In addition, we studied how relevant variables related to farming practices and farm characteristics may affect fly and disease incidence. Our data show that L. ingenua and green mold incidence are associated and that preventative measures such as sanitation and new technologies to reduce human-substrate contact are correlated with reduced green mold incidence. In addition, data indicated farm characteristics such as the proximity to neighboring farms as well as an organic mushroom growing regime are associated with fly incidence.