Search

Green mold ( Trichoderma aggressivum ) is an invasive disease of commercial mushrooms introduced into the United States from Europe that now has spread to commercial mushrooms throughout North America. We examined potential sources of invasive green mold inoculum and the association with different compost filling technologies on a large actively producing commercial mushroom farm. Green mold foci were sampled bed by bed, which generated 20,906 data points. Logistic regression was used to determine treatment differences. Mechanical filling of compost into the beds reduced green mold incidence over hand filling, apparently due to the reduced incidence of worker contact with the floor and between beds. Lower growing beds located closer to the floor had a higher incidence of green mold for both mechanical and hand-filled beds. We conclude that mechanical filling and generally reducing contact with the floor and between beds will reduce spread of green mold in commercial mushroom production., Competing Interests: The author(s) declare no conflict of interest.

Many 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., (© The Author(s) 2021. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Statistical analyses were performed on spatial distributions of mushroom green mold foci caused by Trichoderma spp. in 30 standard Pennsylvania doubles (743 m 2 production surface) selected at random from over 900 total crops mapped. Mapped production houses were divided into four tiers of six beds each with 16 sections per bed (total = 384 sections per double). Each section contained approximately 2 m 2 . Green mold foci were mapped according to presence or absence in each section as they became visible during the course of the mushroom production. There was a trend toward higher disease incidence at the ends of the doubles, although this was not consistent from level to level. Spatial analysis revealed that green mold foci were more likely to occur in neighboring sections along the beds rather than above, below, or across from each other. Cultural practices that were associated with movement along the beds, i.e., nutrient supplementation, spawning, bed tamping, surface covering, etc., were considered the most likely factors influencing the incidence of green mold in spawned compost. Airborne contamination was considered a less likely source of inocula contributing to epidemic development. Sanitation practices that reduce spore loads along the beds are expected to provide the greatest degree of green mold control.