UniversePG I www.universepg.com 159 Evaluation of Some Fungicides against Collar Rot Disease of Soybean Md. Maksuder Rahman 1 , Mahbuba Kaniz Hasna 2 , Nahar Shumsun 1 , Raqibul Hasan 1 , Md. Nazizul Islam 3 , Md. Humayun Kabir 1 , and Mohammad Delwar Hossain 1 * 1 Department of Plant Pathology, Bangladesh Agricultural University, Mymensingh, Bangladesh; 2 Plant Pathology Division, Bangladesh Institute of Nuclear in Agriculture, Mymensingh, Bangladesh; and 3 Department of Environmental Science, Bangladesh Agricultural University, Mymensingh, Bangladesh. *Correspondence: delwarmhossain@gmail.com (Dr. Mohammad Delwar Hossain, Professor, Dept. of Plant Pathology, Bangladesh Agricultural University, Mymensingh. Bangladesh). ABSTRACT A number of selected fungicides were evaluated to determine their efficacy for controlling collar rot disease of soybean plants caused by Sclerotium rolfsii. The experiment was conducted under the controlled condition at the Plant Pathology Laboratory and Field laboratory of BINA, Bangladesh Agricultural University campus from November 2018 to August, 2019. In-vitro research was done for the observation of radial mycelial growth of S. rolfsii on potato dextrose agar (PDA), treated with five fungicides viz. Antracol 70 WP (T1), Ridomil Gold MZ 68 WP (T2), Secure 600 WG (T3), Bavistin DF (T4), Dithane M-45 (T5) and one non-treated (T0) treatment. The highest percentage of mycelial growth inhibition of S. rolfsii in PDA medium was recorded in treatment T5 (Dithane M-45) 100% and lowest in treatment T3 (Secure 600 WG) 37.33% at 6 days after inoculation. Then the selected five fungicides were again applied to pot under controlled conditions to observe the best effect of selected fungicides against collar rot pathogen of soybean plants. The inoculation was done on a variety of BINA soybean 4 in pot condition. The highest mortality percent for the collar rot disease was found in treatment T0 (controlled) 100% soybean plants conversely, the lowest mortality percent was found in treatment T5 (Dithane M-45) 27.28% besides 38.92% in T2 (Ridomil Gold MZ 68 WP), 43.42% in T1 (Antracol 70 WP), 46.18% in T3 (Secure 600 WG) and 50.00% in treatment T4 (Bavistin DF) respectively. Thus, Dithane M-45 was found superior in controlling collar rot pathogen S. rolfsii of Soybean over all other fungicides tested in both in vitro and in vivo. Keywords: Fungicide, Collar rot disease, Sclerotium rolfsii, Evaluation, and Soybean. 1. INTRODUCTION: Soybean (Glycine max L. Merr.) is a leguminous crop and a good source of protein and vegetable oil. Soybean is providing 40% protein. It can play a vital role in balancing the protein deficiency of our diet (Mondal and Wahhab, 2001; Rahman, 2003). Soy- bean production of Bangladesh is 1.59 t/ha which is much lower than the world average (2.53 t/ha) (FAO, 2013). Soybean raw materials are used in different industries. Different soya foods are also prepared from soybean (Hossain et al., 1992). Soybean can fix to an extent of 300kg Nitrogen/ ha/year and reduce the nitrogen requirement by 25- 75% with Bradyrhizobium japonicum. Moreover, Soybean can fix atmospheric nitrogen symbiotically and therefore, through symbiosis about 80-90% nitrogen demand could be supplied by soybean (Keyser and Li, 1992). Thus this crop enhance soil fertility and economizes crop production not only for themselves but also for the next cereal crops and other non-legume crops grown in rotation and thereby, minimizing the regular rate of nitrogen fertilizer. American Journal of Pure and Applied Biosciences, 2(5), 159-166, 2020 Publisher homepage: www.universepg.com, ISSN: 2663-6913 (Online) & 2663-6905 (Print) https://doi.org/10.34104/ajpab.020.01590166 American Journal of Pure and Applied Biosciences Journal homepage: www.universepg.com/journal/ajpab