Survey and incidence of charcoal rot of soybean in major soybean-growing districts of Chhattisgarh

Introduction

Soybean (Glycine max (L.) Merr.) is an economically important leguminous oilseed crop belonging to the family Fabaceae and subfamily Papilionoideae. It has a somatic chromosome number of 2n = 40, and Glycine soja is regarded as its wild progenitor. The crop is believed to have been domesticated in ancient China and later spread worldwide as a major source of edible oil and plant protein (Hymowitz, 1970 and Singh, 2010) [5,9] . Soybean seeds contain about 36-40% protein and 18-20% oil, along with essential amino acids (notably lysine), vitamins, and minerals, making it a valuable component of human diets and livestock feed (Liu, 1997; Smith & Huyser, 1987) [6,10] .Globally, soybean ranks among the most important oilseed crops, and in India, it occupies a significant place in the oilseed economy; the country ranks among the top five producers in the world, with cultivated area reported around 13 million hectares and production approximately 15 million tonnes in recent seasons, and an average productivity typically near 1.0-1.1 t/ha. During 2024-25, soybean in India covered about 126.9 lakh hectares with production around 125-126 lakh tonnes and average productivity nearly 1,060 kg/ha. (Anonymous 2025) [2] . In India the major soybean growing states include Madhya Pradesh, Maharashtra, Rajasthan and others, while Chhattisgarh has also integrated soybean notably into its kharif agriculture, with the state's agro-climatic conditions favouring various high-yielding, disease-resistant varieties tailored for local production systems contributing to regional oilseed supply and farmer livelihoods. In Chhattisgarh, soybean is cultivated over an area of 31.51 thousand hectares, with an average productivity of 841 kg per hectare (Anonymous 2025) [2] . This indicates a moderate yield level in the state, reflecting the influence of local agro-climatic conditions and crop management practices on soybean production District-level analyses indicate variability in trends of area, production, and productivity over time, with some districts (e.g., Rajnandgaon, Kabirdham, Mungeli) showing increasing soybean production trends, while others (e.g., Raipur, Bilaspur, Durg) Charcoal rot is a soil-borne fungal disease of soybean caused by Macrophomina phaseolina. It develops under hot, dry conditions, infects roots and stems, and produces charcoal-like microsclerotia. Infected plants wilt, turn chlorotic, and often die prematurely, leading to significant yield loss. In Chhattisgarh, surveys have shown charcoal rot affecting soybean across major growing areas with high disease incidence, especially in districts like Durg, Rajnandgaon, Mungeli, Bemetara and Kawardha; average disease incidence has been reported up to about 42 % in some soybean belts, with variability across seasons and locations.

Materials and Methods

An extensive field survey was conducted during Kharif 2023-24 and 2024-25 in major soybean-growing districts of Chhattisgarh, namely Balod, Baloda Bazar, Bemetara, Durg, Kabirdham, Khairagarh-Chhuikhadan-Gandai (KCG), Raipur, and Rajnandgaon. The objective of the survey was to assess the prevalence and incidence of charcoal rot disease of soybean caused by Macrophomina phaseolina. A total of 23 villages across the selected districts were surveyed, representing diverse agro-climatic conditions, soil types, soybean varieties, and crop management practices. Charcoal rot incidence was recorded based on visible symptoms such as, Sudden wilting and drying of plants, Shredding of stem tissues, Presence of black microsclerotia in the stem and root tissues.

Result and Discussion

An extensive survey was carried out during kharif 2023-24 and 2024-25 in major soybean-growing districts of Chhattisgarh, including Balod, Baloda Bazar, Bemetara, Durg, Kabirdham, Khairagarh-Chhuikhadan-Gandai (KCG), Raipur, and Rajnandgaon to assess the prevalence and incidence of charcoal rot disease caused by Macrophomina phaseolina. The survey encompassed 23 villages representing different soil types, varieties, and management conditions (rainfed and irrigated). The data presented in Table 1 indicated that the disease incidence ranged from 13.79 to 41.30% during 2023-24 and 18.00 to 35.48% during 2024-25, with an overall mean range of 16.51 to 37.32% across locations. The highest mean disease incidence (37.32%) was observed in Newaspur (Bemetara) under rainfed conditions, whereas the lowest mean incidence (16.51%) was recorded in Atariya (Rajnandgaon) under irrigated condition. Among districts in Table 2, Bemetara and Kabirdham recorded comparatively higher mean disease severity (30-37%), followed by Raipur and Khairagarh-Chhuikhadan-Gandai KCG (28-35%), while Rajnandgaon and Durg exhibited relatively lower incidence (16-26%). The higher disease levels in Bemetara and Kabirdham might be attributed to continuous soybean cultivation, presence of susceptible local varieties, and favorable soil moisture stress conditions prevalent during the crop maturity stage. Fields sown with local varieties exhibited consistently higher charcoal rot severity compared to improved varieties such as JS 335, JS 20-98, JS 95-60, JS 97-52, and RSC 11-72. Early sown fields (first fortnight of June) generally showed lower disease incidence, whereas late-sown crops (July) recorded higher infection possibly due to terminal moisture stress and higher soil temperature during pod filling. The disease was more prevalent in Kanhar soils under rainfed conditions, which favor the development of M. phaseolina due to their cracking nature and tendency to dry rapidly after rainfall. In contrast, irrigated fields and Bhata or Dorsa soils exhibited relatively lower disease intensity, indicating the role of soil moisture availability in disease suppression. Overall, disease severity in 2023-24 was slightly higher than in 2024-25, indicating that annual climatic variation, particularly rainfall distribution and temperature during maturity, significantly influenced disease expression. The present findings corroborate the results of Amrate et al. (2024) [4] , who reported widespread occurrence of charcoal rot in central India with severity ranging between 20-60%, particularly under rainfed conditions. The higher disease incidence under moisture-stressed environments suggests that M. phaseolina thrives in high temperature and low soil moisture situations, leading to rapid colonization of host tissue. Adoption of resistant varieties, timely sowing, and irrigation during critical stages could be effective measures to reduce disease intensity. Continuous monitoring and mapping of disease distribution will help in developing location-specific management strategies for sustainable soybean production in Chhattisgarh. The present findings were consistent with Almeida et al. (2001) [3] , who reported that soybean root infection occurred in all four growing seasons under both no-till and conventional systems. However, during drought years (1998-99 and 1999-2000), disease severity at the final growth stage was 22-25% higher in the conventional system compared to the no-till system. Disease development, measured by the area under the disease progress curve (AUDPC), also differed significantly between the two systems during these seasons. Several pathogens, including Macrophomina phaseolina, survived in soybean debris left on or buried in soil, with M. phaseolina showing the ability to survive and multiply effectively. RAPD analysis of 55 isolates grouped them into three genetic clusters, indicating low genetic variability within groups, possibly due to the absence of a sexual stage and seed transmission. Different haplotypes were even found within the same root, showing genetic diversity across soybean-growing regions of Brazil. The present findings were in agreement with Saikrishna (2022) [7] , who conducted a roving survey in Telangana during 2019 to study the occurrence of Macrophomina phaseolina in different crops. Disease incidence varied among crops and locations. The highest incidence (64%) was recorded in soybean in Nizamabad district. In other crops, incidence reached 49.25% in maize, 62% in castor, 40% in sesame, and the lowest (25%) in red gram. The soil pH of infected fields ranged from 5.7 to 6.2, and temperatures varied between 27 °C and 32 °C, indicating that warm conditions favored disease development. The present findings agreed with Sandhu (2025) [8] , who reported that Macrophomina phaseolina is a serious soil-borne pathogen causing charcoal rot in soybean, especially under high temperature and drought conditions. The fungus infects a wide range of host plants, making its management difficult. Infected soybean samples were collected from different regions and isolated on Potato Dextrose Agar after surface sterilization. The fungus showed typical mycelial growth and sclerotia formation within 2-3 days at 25 ± 1 °C. Identification was based on morphological characters and pathogenicity tests. The study also revealed variability among isolates, indicating differences in structure and possible virulence levels.

Acknowledgement

I express my sincere gratitude to my respected guide and advisory committee for their valuable guidance, encouragement, and constructive suggestions throughout this research work. I am thankful to the Department faculty and staff for their support. I also extend heartfelt thanks to my family and friends for constant motivation and encouragement.

Conclusion

The study confirms that charcoal rot is widely distributed across soybean-growing districts of Chhattisgarh, with disease incidence reaching up to 37.32% in severely affected areas. Environmental factors such as high temperature, terminal moisture stress, rainfed cultivation, and susceptible local varieties significantly influenced disease development. Improved varieties, timely sowing, and irrigation during critical growth stages reduced disease severity. Continuous monitoring and location-specific management strategies are essential to minimize yield losses and ensure sustainable soybean production under changing climatic conditions in the state.

References

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