59   Interaction studies on Rhizoctonia solani , sheath blight pathogen and brown plant hopper (Nilaparvata lugens) in rice Reddy Kumar AV 1 *, N Kiran Kumar 2 , VB Sanath Kumar 3 , L Vijaykumar 4 , SB Yogananda 5 1 Department of Plant Pathology, CoA (UASB), V. C. Farm, Mandya, Karnataka, India 2 Department of Plant Pathology, CoA (UASB), V. C. Farm, Mandya, Karnataka, India 3 (AICRP) ZARS(UASB), V. C. Farm, Mandya, Karnataka, India 4 Department of Entomology, CoA (UASB), V. C. Farm, Mandya, Karnataka, India 5 Department of Agronomy, CoA (UASB), V. C. Farm, Mandya, Karnataka, India *Corresponding author e-mail: rk527930@gmail.com Oryza Vol. 62 Issue 1 2025 (59-67) DOI https://doi.org/10.35709/ory.2025.62.1.7 Received : 13 September 2024 Accepted: 27 March 2025 Published : 31 March 2025 ABSTRACT The association of sheath blight (Rhizoctonia solani), a widespread fungal disease in rice and the brown planthopper (Nilaparvata lugens), a major rice pest, presents a significant challenge in rice production. Brown planthopper feeding may increase plant susceptibility to sheath blight by weakening plant defenses and facilitating fungal invasion through the wounds they create. The synergistic effects of brown planthopper and sheath blight infestation result in significant yield losses, complicating management strategies. Three sets of interactions were conducted, among the three sets, the highest disease severity was recorded in the set 1 (Simultaneous inoculation of BPH and Rhizoctonia solani) (73.33%) followed by set 2 (Release of BPH and subsequent inoculation of Rhizoctonia solani after 7 days) (60%) and least disease severity was observed in set 3 (BPH release after 7 days of inoculation with Rhizoctonia solani) (57.04%). This study aims to investigate the complex interaction between brown planthopper and sheath blight in rice, focusing on how these interactions influence disease progression and pest dynamics, and to provide insights into improved management strategies for rice farmers facing both threats. Key words: Interaction, rice, sheath blight, brown plant hopper INTRODUCTION Sheath blight, caused by the fungal pathogen Rhizoctonia solani, is a prevalent disease in rice that leads to significant yield losses. The disease is characterized by blight symptoms on the leaf sheath, resulting in reduced photosynthetic efficiency and lower grain production. Environmental conditions, such as humidity and temperature, play a significant role in the disease's progress, making it particularly problematic in rice cultivation areas that favor fungal growth (Cheng et al., 2013). The brown planthopper is a notorious pest in rice (Oryza sativa) cultivation, known for causing significant damage through its feeding activities. BPH feeds on the phloem sap of rice plants, leading to reduced plant vigor, stunted growth, and even complete crop failure under severe infestations. BPH infestation can be devastating, especially in tropical regions, where it poses a substantial risk to rice yield (Ghobadifar et al., 2016). Additionally, BPH acts as a vector for several viral diseases, importantly impacting the overall health of rice plants and enhancing the severity of sheath blight infections. The feeding habits of BPH influence sheath blight development in several ways. Firstly, the mechanical damage inflicted by BPH feeding can open pathways for fungal spores, facilitating infection. Secondly, the stress on plants due to BPH infestation may weaken their defences against pathogens, making them more susceptible to sheath blight (Ramli et al., 2018). As such, the synergy between BPH feeding and sheath blight presents a dual threat to rice production that requires comprehensive study and management approaches.