Eco-friendly management of blast in pearl millet

Introduction

Pearl millet, scientifically known as Pennisetum glaucum L., and commonly referred to as bajra or bajri, belongs to the Poaceae family. It is an important cereal crop cultivated extensively for both human consumption and livestock feed and fodder. Being a C 4 plant, pearl millet possesses high photosynthetic efficiency and superior dry matter production capacity, which enable it to thrive under adverse agro-climatic conditions such as drought, low soil fertility, and high temperatures. Owing to its remarkable adaptability, it serves as a staple food crop for resource-poor and smallholder farmers across Asia and Africa. Globally, pearl millet contributes nearly half of the total millet production and ranks as the sixth most important cereal crop after maize, rice, wheat, barley, and sorghum. In India, the major pearl millet growing states include Rajasthan, Maharashtra, Uttar Pradesh, Gujarat, and Haryana, which together contribute nearly 90 percent of the national production. In Gujarat, pearl millet is cultivated in 26 out of 33 districts during different seasons. During kharif 2024-25, the crop occupied an area of 1.68 lakh hectares with a production of 3.10 lakh tonnes and an average productivity of 1844 kg ha⁻¹. In the summer season, it covered 3.22 lakh hectares with a production of 9.78 lakh tonnes and productivity of 3035 kg ha⁻¹, whereas in the coastal semi-rabi season, it occupied 0.070 lakh hectares with a production of 0.160 lakh tonnes and productivity of 2291 kg ha⁻¹. Overall, pearl millet covered 4.97 lakh hectares in Gujarat with a total production of 13.04 lakh tonnes and an average productivity of 2390 kg ha⁻¹ during 2023-24. Nutritionally, pearl millet grains contain approximately 11.60 percent protein, 5.00 percent fat, 67.00 percent carbohydrates, and 2.70 percent minerals (Gill, 1991) [3] , making it an important source of nutrition in arid and semi-arid regions. Despite its adaptability and nutritional significance, pearl millet production is constrained by several biotic stresses, among which blast disease caused by Pyricularia grisea is one of the most destructive. The disease has emerged as a serious threat to pearl millet cultivation in several parts of India, causing substantial losses in both grain and forage yield. The incidence of pearl millet blast on commercial hybrids has increased alarmingly in many states of the country (Thakur et al., 2009) [20] .

The pathogen is capable of infecting plants at all growth stages, from seedling to maturity, leading to severe reductions in grain yield and forage production (Lukose et al., 2007) [8] . Management of blast disease has relied heavily on synthetic chemical fungicides. Although these chemicals provide rapid disease suppression, their continuous and indiscriminate use has resulted in environmental pollution, accumulation of toxic residues in food products, and development of fungicide-resistant pathogen strains. Therefore, there is an increasing need to develop ecofriendly and economically viable disease management strategies. Among the alternative approaches, biological control using beneficial microorganisms has emerged as a promising and environmentally safe method for the management of fungal diseases. In this context, Trichoderma harzianum and Pseudomonas fluorescens have gained considerable attention because of their strong antagonistic activity against several plant pathogens and their additional role in promoting plant growth (Kashyap et al., 2020) [5] . Species of Trichoderma suppress pathogens through various mechanisms such as mycoparasitism, production of hydrolytic enzymes, competition for nutrients and space, and secretion of antifungal metabolites (Rai et al., 2016; Kashyap et al., 2017) [13,6] . Furthermore, they enhance plant growth by producing phytohormones including indole acetic acid, gibberellins, and cytokinins, thereby improving root colonization and nutrient uptake. Similarly, Pseudomonas fluorescens, an important plant growth-promoting rhizobacterium (PGPR), exhibits biocontrol activity through the production of siderophores, antibiotics, and other secondary metabolites that inhibit pathogen growth and induce systemic resistance in plants (Srivastava et al., 2013; Solanki et al., 2014) [19,18] . Therefore, the integration of biological agents offers a sustainable and eco-friendly approach for the effective management of pearl millet blast disease.

Materials and Methods

A field experiment was carried out at the Pearl Millet Research Station of Junagadh Agricultural University, Jamnagar, Gujarat, during the consecutive kharif seasons of 2023, 2024 and 2025 to study the eco-friendly management of blast in pearl millet. The experiment was laid out in randomized block design with three replications at spacing of 60 ×10 cm with 4.0 × 3.0 m gross plot size. Standard agronomic practices of NPK-80 kg, 40kg, 0 kg were followed at the time of crop growth period. A variety dhanshakti was used in this experiment by imposing the following treatments: (Table 1). Foliar application of different bio agents were carried out for the management of pearl millet blast. The first spray was given just after appearance of the disease and second spray was given at an interval of 15 days. Ten plants were selected randomly from each plot for scoring the disease intensity. These plants were observed for disease intensity from upper, middle and lower leaves using disease rating scale of 0-9. Observations on disease intensity were recorded at 45, 60 and 75 DAS. Per cent disease intensity (PDI) was calculated by using the following formula.

Sum of total rating Total number of leaves observed × Maximum disease rating ×100

Blast disease rating scale (0-9)

Scale Description 0

No lesions 1 Small brown specks of pinhead size without sporulating center 2 Small roundish to slightly elongated, necrotic grey spots, about 1-2 mm in diameter with a distinct brown margin, lesions are mostly found on the lower leaves 3

Lesion type is the same as in scale 2, but significant number lesions are on the upper leaves 4

Typical sporulating blast lesions, 3 mm or longer, infecting less than 2% of the leaf area 5

Typical blast lesions infecting 2-10% of the leaf area 6

Blast lesions infecting 11-25% leaf area 7

Blast lesions infecting 26-50% leaf area 8

Blast lesions infecting 51-75% leaf area 9

More than 75% leaf area affected

Results and Discussion

The field experiment comprising nine treatments including an untreated control was conducted during kharif 2023, 2024, and 2025 to evaluate their efficacy against blast disease of pearl millet. The pooled results of three years presented in Table 2 [2] . The reduction in blast disease intensity observed with Pseudomonas fluorescens might be due to induction of systemic resistance and production of antibiotics, siderophores, and other secondary metabolites that inhibit the growth and development of the pathogen. Similar findings were reported by Krishnamurthy et al. (1998) [7] and Bhaskar et al. (2021) [1] , who observed substantial reduction in blast incidence with the application of Pseudomonas fluorescens. Similarly blast disease control was recorded from sprays of P. fluorescens in finger millet by Netam et al. (2016) [10] . Same result was found by Ramappa et al., (2002) [14] obtained good control by two sprays of P. fluorescens against Pyricularia grisea. Sitther and Gananamanickan (1996) [17] reported the effectiveness of six strains of Pseudomonas fluorescens for their ability to inhibit the blast fungus. The application of bioagents in reducing the blast disease of finger was also reported by Senthil et al., (2012) [15] . The effectiveness of organic formulations such as Jivamrut, Panchgavya, cow urine, and NSKE may be associated with enhancement of beneficial microbial activity in the rhizosphere along with the presence of antifungal compounds that suppress pathogen development. These organic treatments possibly improved plant vigor and enhanced natural resistance against blast infection. The present investigation corroborates earlier reports suggesting that bioagents and organic formulations provide sustainable, eco-friendly, and effective management of blast disease under field conditions. Furthermore, Jambhulkar et al.

(2018) [4] also reported that the combined use of biological agents enhances disease suppression and improves overall crop health.

Yield and Economics

The three-year pooled results presented in Table 4 revealed significant influence of different treatments on grain yield of pearl millet. Among the treatments, Trichoderma harzianum recorded the highest grain yield (2411 kg ha⁻¹) and proved superior over the untreated control. However, it remained statistically at par with Pseudomonas fluorescens (2386 kg ha⁻¹), Bacillus subtilis (2345 kg ha⁻¹), Panchagavya (2307 kg ha⁻¹), and Jivamrut (2301 kg ha⁻¹). The minimum grain yield (1689 kg ha⁻¹) was recorded under the untreated control, indicating severe reduction in crop productivity due to blast disease infection in the absence of management practices. The increased grain yield observed under Trichoderma harzianum treatment may be attributed to effective suppression of blast disease along with enhanced plant growth and nutrient uptake. Trichoderma spp. are known to produce various growth-promoting substances and elicitors that stimulate root development, improve nutrient availability, and enhance physiological activities, ultimately leading to higher crop productivity (Ghorbanpour et al., 2018) [2] . Similarly, Pseudomonas fluorescens and Bacillus subtilis might have improved grain yield through disease suppression and promotion of plant growth by producing beneficial metabolites and enhancing nutrient mobilization. The findings of the present investigation are in accordance with the results of Varshney and Chaube (1997) [21] , who reported that application of Pseudomonas fluorescens and Trichoderma harzianum significantly increased growth and yield parameters in tomato. Likewise, Nezarat and Gholami (2009) [11] observed significant improvement in plant height, 100-seed weight, number of seeds per ear and seed yield in maize following application of beneficial microbial inoculants. Netam et al. (2016) [10] reported that significantly higher grin yield found with three sprays of P. fluorescens in finger millet. The fodder yield data presented in Table 4 also showed significant variation among different treatments. The maximum fodder yield (4883 kg ha ⁻1 ) was recorded with Panchagavya, which remained statistically at par with Bacillus subtilis (4873 kg ha⁻¹), cow urine (4854 kg ha⁻¹), Trichoderma harzianum (4819 kg ha⁻¹), Pseudomonas fluorescens (4808 kg ha⁻¹), and Jivamrut (4668 kg ha⁻¹). The untreated control recorded the lowest fodder yield (3570 kg ha⁻¹). Petro et al. (2020) [12] revealed that foliar spray of Pseudomonas fluorescens at 20 DAS and Trifloxystrob in + Tebuconazole at 35 DAS was found effective with least disease intensity of blast, higher grain and fodder yield. Higher fodder yield under Panchagavya and bioagent treatments might be due to improved plant vigor, enhanced nutrient availability, and reduced disease severity, which collectively promoted better vegetative growth and biomass accumulation. Organic formulations such as Panchagavya and Jivamrut are known to enhance microbial activity in the soil and supply essential nutrients and growth-promoting substances, thereby improving crop growth and fodder production. The overall improvement in grain and fodder yield under biological and organic treatments suggests their potential as eco-friendly and sustainable approaches for blast disease management and productivity enhancement in pearl millet. The highest additional income ₹20548 ha -1 , highest net realization of ₹ 19373 ha -1 and maximum ICBR 1: 17.49 was obtained in the treatment Trichoderma harzianum followed by Pseudomonas fluorescens, Netam et al. (2016) [10] found that cost benefit ratio was also higher in three spray of P. fluorescens, three sprays of Trichoderma harzianum and at par with Ediphenphos in finger millet.

Conclusion

It can be concluded from the above results that the spraying of Trichoderma harzianum (50 g/10 l of water) or Jivamrut (300 ml/10 l of water) in pearl millet against blast disease were found effective to minimize blast intensity, higher grain and fodder yield and additional income also.

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