Lentil, known scientifically as Lens culinaris Medic., is a vital crop globally, especially in regions with dry or semi-dry climates. This pulse crop is not only a rich source of protein, vitamins, and minerals but also plays a key role in improving soil health through nitrogen fixation.

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Despite its importance, lentil farming faces a major threat from collar rot, a destructive disease caused by the soil-borne fungus Sclerotium rolfsii. Recent research published in Indian Phytopathology offers a detailed roadmap for managing this disease using eco-friendly methods.

Global Importance of Lentil Production and Challenges

To understand the significance of this research, it is important to first recognize the scale of lentil production. India, the world’s largest producer and consumer of lentils, cultivates the crop on 14.36 lakh hectares of land, yielding 13.30 lakh tonnes annually.

Globally, lentil production spans 50.1 lakh hectares, contributing 65.4 lakh tonnes to the world’s food supply.

However, up to 25% of this yield is lost to pests and diseases, with collar rot alone causing losses of up to 50% in severe cases.

The fungus responsible for this disease, Sclerotium rolfsii, attacks the base of the plant, leading to wilting, rotting, and eventual plant death. Its ability to survive in soil for years through hardened structures called sclerotia makes it a persistent problem for farmers.

Understanding Collar Rot Disease in Lentils

The study, conducted by researchers from Sardar Vallabhbhai Patel University of Agriculture and Technology in Uttar Pradesh, India, aimed to tackle this issue using biological control agents (BCAs) and organic amendments. The team focused on identifying native strains of Trichoderma, a beneficial fungus, and testing their effectiveness against S. rolfsii.

They also evaluated bacterial bioagents like Pseudomonas fluorescens and organic soil treatments such as vermicompost. The goal was to develop an integrated strategy that reduces reliance on chemical fungicides, which are costly, harmful to the environment, and leave toxic residues in crops.

Innovative Research on Eco-Friendly Disease Control

The research began by isolating S. rolfsii from infected lentil plants collected from farms in Uttar Pradesh. The fungus was grown in Petri dishes on a nutrient-rich medium called potato dextrose agar (PDA) and identified by its white, cotton-like growth and brown sclerotia.

Next, the team collected soil samples from 30 districts across western Uttar Pradesh to isolate native Trichoderma strains. These samples were processed using a special medium that promotes Trichoderma growth while suppressing other fungi. A total of 30 isolates were obtained, each labeled based on their geographic origin, such as the Badaun isolate or Shahjahanpur isolate.

Laboratory Breakthroughs in Fungal Control

In laboratory experiments, the researchers tested how well these bioagents could inhibit S. rolfsii. Using a method called the dual culture technique, they placed a disc of S. rolfsii on one side of a Petri dish and a disc of Trichoderma or a streak of bacteria on the opposite side.

After six days, they measured the growth of the pathogen and calculated the percentage of inhibition. The results were striking. The Badaun isolate of Trichoderma (labeled T16) achieved 87.03% inhibition of S. rolfsii, followed closely by the Shahjahanpur isolate (T15) at 84.81%.

Even more importantly, these treatments completely prevented the formation of sclerotia, the survival structures that allow the fungus to persist in the soil. Among bacterial agents, Pseudomonas fluorescens showed 80% inhibition, while Bacillus subtilis lagged behind at 68.89%.

Field-Tested Solutions for Healthier Lentil Crops

Following these promising lab results, the team conducted field trials during the 2022–2023 Rabi season. They tested nine different treatments, including seed biopriming with Trichoderma or P. fluorescens, soil amendments like vermicompost mixed with bioagents, and a control group with no treatment.

The field experiments followed a randomized block design with three replications to ensure accuracy. Key parameters such as disease incidence (%), yield (q/ha), plant fresh weight (g), and shoot length (cm) were measured.

Why These Results Matter for Sustainable Farming

The field results confirmed the effectiveness of the lab findings. Seed biopriming with the Badaun isolate (T16) reduced disease incidence to 10%, compared to 21.67% in the control group. This treatment also boosted yield to 14.5 quintals per hectare (q/ha), more than double the control group’s yield of 6.5 q/ha.

Seed biopriming with T. harzianum, a well-known biocontrol fungus, also performed well, reducing disease incidence to 11.67% and increasing yield to 14.01 q/ha.

Soil amendments further enhanced these results.For example, combining vermicompost with the Badaun isolate and P. fluorescens (Treatment T6) yielded 13.38 q/ha, while vermicompost with T. harzianum and P. fluorescens (T7) produced 13.08 q/ha.

These treatments not only suppressed the pathogen but also improved plant health, as seen in higher fresh weights (37g for T2 vs. 20g for control) and longer shoots (27cm for T2 vs. 12cm for control).

Overcoming Challenges in Biological Pest Control

The success of these methods lies in their synergy. Trichoderma works by competing with S. rolfsii for space and nutrients, releasing enzymes that break down the pathogen’s cell walls, and stimulating the plant’s natural defenses.

Pseudomonas fluorescens produces antibiotics that inhibit fungal growth, while organic amendments like vermicompost enrich the soil with beneficial microbes and organic matter. Together, these approaches create an environment where the pathogen struggles to survive, allowing the lentil plants to thrive.

The Future of Eco-Friendly Lentil Farming

Another critical advantage of these eco-friendly methods is their cost-effectiveness. Producing Trichoderma on wheat grains costs between ₹50–100 per kilogram, significantly cheaper than chemical fungicides, which can cost ₹300–500 per kilogram. For smallholder farmers, this price difference is crucial.

Adopting seed biopriming with the Badaun isolate could increase a farmer’s income from ₹32,500 per hectare (untreated fields) to ₹72,500 per hectare, assuming a market price of ₹5,000 per quintal. Additionally, organic amendments like vermicompost improve soil structure and water retention, reducing the need for synthetic fertilizers over time.

Building Resilient Farming Systems

However, scaling up these solutions presents challenges. Producing bioagents on a large scale requires sterile laboratory conditions and trained personnel, which may be lacking in rural areas. Environmental factors like soil pH, temperature, and moisture levels can also affect the consistency of bioagents’ performance.

To address this, the researchers recommend establishing community-led biocontrol production units and providing government subsidies to make these technologies accessible to small farmers.

Education and training programs are equally important, as many farmers are unfamiliar with biocontrol methods.
Demonstration plots and workshops led by agricultural extension services could bridge this knowledge gap.

A Blueprint for Sustainable Agriculture

Looking ahead, the study highlights the need for further research to optimize application methods. For instance, adjusting the timing and dosage of bioagent treatments could enhance their effectiveness.

Exploring combinations of multiple bioagents or integrating them with resistant lentil varieties may offer even greater protection against collar rot. Preserving microbial biodiversity is another priority, as native strains like the Badaun isolate demonstrate superior adaptability to local conditions compared to generic commercial products.

Conclusion

In conclusion, this research offers a transformative approach to managing lentil collar rot. By replacing chemical fungicides with natural bioagents and organic practices, farmers can achieve higher yields, healthier soils, and safer food production. For countries like India, where lentils are a dietary staple and a lifeline for millions of farmers, these strategies are not just innovative—they are essential for sustainable agriculture.

The success of the Badaun and Shahjahanpur isolates underscores the value of local biodiversity and the potential of homegrown solutions to global agricultural challenges. As the world grapples with climate change and food security, such eco-friendly practices will play a pivotal role in building resilient farming systems for future generations.

Power Terms

Lentil: A lentil is a type of edible seed from the legume family, scientifically known as Lens culinaris. It is a staple crop grown in dry or semi-dry regions and is rich in protein, fiber, and essential nutrients like iron and folate. Lentils are vital for food security, especially in countries like India, and improve soil fertility through nitrogen fixation, a process where symbiotic bacteria in their root nodules convert atmospheric nitrogen into a form plants can use. Examples include red, green, and brown lentils, which are used in dishes like soups, stews, and salads.

Collar Rot: Collar rot is a plant disease caused by the fungus Sclerotium rolfsii. It attacks the base (collar) of lentil plants, causing wilting, stem rot, and death. The disease is economically significant as it can reduce crop yields by up to 50%. Farmers manage it using bioagents like Trichoderma or soil amendments. Symptoms include white fungal growth and brown sclerotia near infected stems.

Sclerotium rolfsii: A soil-borne fungus that causes collar rot in lentils and other crops. It survives harsh conditions through sclerotia—hard, brown resting structures. This pathogen is destructive because it infects plants at any growth stage and thrives in warm, moist soils. Controlling it requires eco-friendly methods like bioagents, as chemicals are costly and environmentally harmful.

Nitrogen Fixation: A natural process where bacteria in lentil root nodules convert atmospheric nitrogen (N₂) into ammonia (NH₃), enriching the soil. This reduces the need for synthetic fertilizers, lowers farming costs, and improves soil health. For example, lentils planted in rotation with wheat can boost soil nitrogen levels for subsequent crops.

Bioagents: Beneficial microorganisms like fungi (Trichoderma) or bacteria (Pseudomonas fluorescens) used to control pests and diseases. They are eco-friendly alternatives to chemicals, suppressing pathogens through competition, antibiotic production, or boosting plant immunity. For instance, Trichoderma is applied to seeds or soil to protect lentils from collar rot.

Trichoderma: A genus of fungi used as bioagents. Species like T. harzianum combat plant pathogens by producing enzymes (e.g., chitinases) that break down fungal cell walls. They also compete for nutrients and space. Farmers use Trichoderma in seed biopriming or soil treatments to reduce collar rot and improve crop yields.

Pseudomonas fluorescens: A soil bacterium that suppresses plant diseases by producing antibiotics like phenazines. It colonizes plant roots, protecting them from pathogens like S. rolfsii. Farmers apply it as a seed coating or soil drench to enhance lentil growth and reduce collar rot incidence.

Bacillus subtilis: A bacterium used in biocontrol. It produces antifungal compounds and stimulates plant defenses. Though less effective than Pseudomonas in the study, it is still used in organic farming to manage soil-borne diseases.

Vermicompost: Compost made using earthworms to break down organic waste. It improves soil structure, nutrient content, and microbial activity. In the study, vermicompost mixed with bioagents increased lentil yields by 13.38 q/ha, showcasing its role in sustainable farming.

Press Mud: A byproduct of sugar mills, rich in organic matter. Used as a soil amendment, it enhances soil fertility and water retention. In the research, press mud combined with bioagents reduced collar rot incidence in lentils.

Mustard Oil Cake: Residue from mustard oil extraction, used as organic fertilizer. It releases nutrients slowly and improves soil health. Farmers apply it to fields to suppress pathogens and boost crop growth.

Dual Culture Technique: A lab method to test bioagents’ effectiveness. A pathogen and a bioagent (e.g., Trichoderma) are placed on opposite sides of a Petri dish. The bioagent’s ability to inhibit the pathogen’s growth is measured. This technique helped identify the Badaun isolate as the most effective against collar rot.

Radial Growth: The outward spread of a fungus on a growth medium, measured in millimeters. In the study, researchers compared the radial growth of S. rolfsii in the presence of bioagents to calculate percent inhibition.

Percent Inhibition: A formula to measure a bioagent’s effectiveness:

$Percent Inhibition = Control Growth Control Growth - Treated Growth \times 100$

For example, the Badaun isolate showed 87.03% inhibition, meaning it reduced fungal growth by 87%.

Sclerotia: Hard, brown survival structures produced by fungi like S. rolfsii. They allow the fungus to persist in soil for years. Preventing sclerotia formation, as seen with Trichoderma treatments, is key to long-term disease control.

Randomized Block Design: A field experiment layout where plots are grouped into blocks to minimize variability. Each block contains all treatments, ensuring fair comparison. The study used this design to test nine treatments across three replications.

Seed Biopriming: Coating seeds with bioagents or nutrients to enhance germination and early protection. For example, seeds treated with Trichoderma had 10% disease incidence vs. 21.67% in untreated seeds.

Necrotrophic Pathogen: A pathogen that kills host tissue before feeding on it. S. rolfsii is necrotrophic, attacking lentil stems and causing rapid plant death.

Chitinases: Enzymes produced by Trichoderma that break down chitin in fungal cell walls. This weakens pathogens like S. rolfsii, slowing their growth.

Glucanases: Enzymes that degrade glucan, a component of fungal cell walls. Combined with chitinases, they enhance Trichoderma’s antifungal activity.

Induced Systemic Resistance (ISR): A plant defense mechanism activated by bioagents like Trichoderma. ISR primes the plant to respond faster to infections, reducing disease severity.

Phenazines: Antibiotics produced by Pseudomonas fluorescens that inhibit fungal growth. They play a key role in suppressing S. rolfsii in lentils.

Pyoluteorin: Another antibiotic from Pseudomonas that targets pathogens. It complements phenazines in protecting plants.

Microbial Antagonism: Competition between microbes for resources. Beneficial microbes like Trichoderma outcompete pathogens, limiting their spread.

Quintal: A unit of yield measurement (1 quintal = 100 kg). The study reported lentil yields up to 14.5 q/ha with bioagent treatments, highlighting their impact on productivity.

Reference:

Singh, A., Mishra, P., Khilari, K. et al. Ecofriendly management of lentil (Lens culinaris Medic.) collar rot (Sclerotium rolfsii Sacc.) for sustainable organic production. Indian Phytopathology (2025). https://doi.org/10.1007/s42360-025-00845-2

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