Md Asif Hasan Mazumder Niloy ¹ Sharita Islam ¹ Tasnimul Ferdous ¹ Soyabur Rahman ² Sabina Yesmin ³ Dr. Sk. Shahriar Bin Rasul, ¹ Jebunnahar Khandakar ^1*

• ¹ Independent University, Bangladesh, Dhaka, Bangladesh
• ² Mushroom Development Institute, Dhaka, Bangladesh
• ³ Bangladesh Agricultural Research Institute, Dhaka, Dhaka, Bangladesh

Mold contamination, particularly from green and orange molds, poses a serious threat during the spawn running stage in mushroom cultivation, exacerbated throughout the during hot and humid summer months. Despite extensive studies on green mold, orange mold remains underexplored. Consequently, this study comprehensively investigated orange mold contamination, focusing on identifying the causaltive agent, assessing its pathogenicity, and exploring potential countermeasures. Internal Transcribed Spacer (ITS) region sequencing was used to confirm the causative entity, while the dual confrontation plate method was employed to assess pathogenicity. Furthermore, control strategies, including plant extract, in vitro media performance, and substrate characteristics, were explored. For estimated substrate qualities, fFourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) studies, along with analysis of physicochemical properties including the C: N ratio, carbon, protein, and minerals content were assessed. The result confirmed Neurospora sitophila as the causal entity. The pathogenicity assessments indicated that this mold impedes the colonization of mushroom mycelium by competing for nutrients and space. The in-vitro studies of media performance demonstrated that Neurospora sitophila growth was inhibited at varying rates in nitrogen-supplemented media in the presence of available carbon. Noteworthy, SEM analysis revealed Neurospora sitophila heavily colonized sawdust but not rice straw, attributed to a higher C: N ratio in sawdust. These findings suggest that lower C: N ratio negatively affect affects orange mold growth, highlighting nitrogen supplementation in sawdust or using rice straw as effective strategies to manage orange mold contamination in mushroom cultivation. This strategy could also be applied to other food industries where Neurospora is used.