Seed Treatment in Indian Mustard: Alternaria Blight, White Rust and Early Vigour in Rajasthan and Madhya Pradesh

Executive Summary

Indian mustard is dressed before sowing as a matter of routine, but the two diseases that decide the crop are not equally reachable from the seed bag. White rust (Albugo candida) has an established seed-treatment answer in Indian practice. Alternaria blight (Alternaria brassicae) does not: the package of practice manages it with mancozeb sprays from about 40 days after sowing, and no seed dressing appears in that recommendation. A grower who buys treated mustard seed believing it settles Alternaria blight is buying the wrong thing.

The seed still earns its treatment for two other reasons. Across 24 locations in Madhya Pradesh's Gird belt — Morena, Bhind and Gwalior, which supply more than 70 per cent of the state's mustard — a two-season survey found Alternaria blight severity between 28.56 and 44.16 per cent, with no field free of the disease. And the seed travels with its own inoculum: at Pantnagar, about 42.6 per cent of seeds from silique lots at 65 per cent disease severity carried A. brassicae, and the pathogen survived storage.

Why the Mustard Seed Is a Special Case

Mustard is a small-seeded, low-seed-rate, largely rainfed rabi crop. Akhouri Nishant Bhanu, Kartikeya Srivastava and Rajesh Kumar Singh, of the Institute of Agricultural Sciences at Banaras Hindu University, Varanasi, put the recommended rate at four to five kilograms of seed per hectare in rows 45 cm apart, sown 2.5–3.0 cm deep. Their 2019 review in Acta Scientific Agriculture states the standard pre-sowing practice plainly: seed should be treated with thiram or captan at 2.5 g per kg of seed.

A tiny seed rate and a low per-kilogram dose are why mustard seed treatment is cheap per hectare — and why it has to be got right, since an error in rate is applied to every plant in the field.

The Practice as It Stands in India

The BHU review is specific about where a seed dressing belongs. Damping off: a systemic fungicide such as carboxin or carbendazim at 2 g per kg of seed, with the note that Trichoderma seed treatment is now recommended but protects the seed against externally seed-borne pathogens. Downy mildew at the seedling stage: seed treatment with metalaxyl (marketed as Apron 35 SD) at 6 g per kg of seed, followed where needed by mancozeb at 0.2 per cent.

A 2026 review of Brassica juncea by Ashita Pawaiya and colleagues at Jawaharlal Nehru University, New Delhi, in Plant Signaling & Behavior, draws the same line. White rust: seed treatment with Apron 35 SD at 6 g per kg, plus two to three mancozeb sprays, against a reported yield loss of up to 47 per cent. Alternaria blight: removal of weeds and diseased debris, and mancozeb at 2 kg per 1,000 litres at 15-day intervals from 40–45 days after sowing, against a reported loss of 10–70 per cent. No seed treatment appears in the Alternaria row.

Mustard's best-supported seed-treatment target is an oomycete, not the fungus that gives the crop its worst foliar disease.

Disease Pressure, Measured: What a Mustard Seed Treatment Is Up Against

Loss estimates for Alternaria blight are wide, and the width is information. The Gwalior survey team cites P. D. Meena and co-workers' 2010 review for losses of 15–71 per cent in productivity and 14–36 per cent in oil content, with reduced seed size and seed discolouration; the JNU review cites 10–70 per cent. Neither band supports a yield promise. Which crop is hit depends on species and state: Meena, P. K. Rai and Pankaj Sharma, drawing on All India Coordinated Research Project on Rapeseed-Mustard severity data for 2004–2020 and publishing in the Journal of Oilseeds Research in 2023, report average severity of 39.3 per cent on toria (Brassica rapa ssp. toria) and 34.9 per cent on yellow sarson, against 31.1 per cent on B. juncea. By state the same dataset puts Rajasthan at 15.5 per cent — the lowest among the major rapeseed-mustard states — and Madhya Pradesh at 25.3 per cent, against 48.5 per cent in Uttarakhand and 43.7 per cent in Punjab.

State averages describe the trend; field numbers describe the problem. Babli, R. K. Pandya and Manoj Kumar Ahirwar, of the Department of Plant Pathology at the College of Agriculture, RVSKVV, Gwalior, surveyed 24 locations across three districts during rabi 2020–21 and 2021–22, sampling 25 plants per field at 90–100 days after sowing.

Madhya Pradesh: the Gird belt

Reported in Plant Archives in 2025, not one of the 24 locations was free of Alternaria blight. Percent disease index ranged from 33.19 to 44.16 per cent in 2020–21 and from 28.56 to 37.44 per cent in 2021–22; district means over the two seasons were 40.80 per cent for Morena, 39.95 per cent for Bhind and 30.87 per cent for Gwalior, against an overall mean of 37.20 per cent. The survey team chose these three districts because they jointly contribute more than 70 per cent of the state's rapeseed-mustard production.

Rajasthan: a lower average, but not uniformly

The AICRP state average of 15.5 per cent is roughly half the Madhya Pradesh figure, but it conceals the humid south-eastern plain — and the seed-treatment trial described next was run in precisely that zone. Disease pressure is a local variable, and the seed-treatment decision should follow it.

The Rajasthan Seed-Treatment Trial: Strong Ranking, Large Numbers, Read With Care

Geetesh Gupta and colleagues — from Career Point University, Kota; the College of Agriculture, Hindoli, under Agriculture University, Kota; and SKN College of Agriculture, Jobner, under Sri Karan Narendra Agriculture University — tested seed treatment alone in Rajasthan's humid south-eastern plain zone. Reporting in the Current Journal of Applied Science and Technology in 2023, they compared 13 treatments in a randomised block design with three replications: an unsoaked control, a water-soaked control, four salt soaks (1 per cent KCl, K2SO4, CaCl2 and NaCl), carbendazim 50 per cent WP, mancozeb M-45, each salt combined with mancozeb, and carbendazim with mancozeb.

Carbendazim plus mancozeb gave the best growth and yield attributes and the highest seed, stover and biological yields, with reported increments of 111.96 and 95.67 per cent in seed yield against the unsoaked and water-soaked controls. White rust and Alternaria blight were most severe in those two controls and least severe where seed had been treated with that combination.

Two qualifications matter. The best treatment was statistically at par with K2SO4 plus mancozeb, KCl plus mancozeb and mancozeb alone, while the salt soaks without a fungicide did not reach that group — the fungicide carried the effect and the salts added nothing. And a seed-yield increment near 100 per cent describes a low-yielding control in one experiment, not a transferable expectation. The useful output is the ranking: a contact plus a systemic fungicide, applied to the seed, beat salt soaks and untreated seed where both diseases were present.

White Rust: The Better-Supported Case for Dressing the Seed

For white rust the evidence is older and more consistent. Komal Kumawat, S. Hashmi and colleagues at Bundelkhand University, Jhansi, tested nine seed treatments in a randomised block design with three replications during rabi 2024, scoring white rust incidence at 30, 45 and 60 days after sowing. Mancozeb at 3 g per kg of seed gave the lowest mean incidence at 16.80 per cent, ahead of carbendazim at 17.80 per cent and Trichoderma harzianum at 19.04 per cent. Botanical extracts gave moderate control, and every treatment reduced incidence against the untreated control.

The mechanism explains why white rust behaves differently from Alternaria blight: Albugo candida can travel on and in seed, and metalaxyl is a systemic, oomycete-specific fungicide that moves into the seedling from the treated seed. Sneh Mathur and Maheep Bhatnagar, reporting in the Indian Journal of Plant Protection in 1992, found that metalaxyl seed treatment needed comparatively high rates for complete control, that seedling protection persisted about a month, and that the strongest result came from adding two foliar sprays.

Yaduka Agrotech Limited holds a CIB&RC Section 9(4) registration for Metalaxyl-M 31.8% ES as a wet-slurry seed dresser covering mustard downy mildew and white rust at 3.5 ml per kg of seed, and a second registration for Metalaxyl 35% W.S. under which white rust of rapeseed-mustard is an approved use. Those are regulatory facts about what the company is licensed to sell, not efficacy evidence; the efficacy evidence here comes from the trials cited, and where our certificate and a trial differ on rate, the certificate governs what we may state.

The Seed Carries Its Own Inoculum

Why should a seed dressing matter for a disease managed by spraying leaves? Because in mustard the two are joined at the seed. Ruchi Tripathi, Rahul Purohit, A. K. Tewari and Shweta Kala, of G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, traced Alternaria brassicae from silique to seed and followed it through storage, publishing in Australasian Plant Pathology in 2025.

Silique-to-seed transmission was about 42.6 per cent in seeds from silique lots showing 65 per cent disease severity. Disease development was favoured by average relative humidity above 80 per cent with mean maximum temperatures near 29 °C, and earliest symptoms appeared 98 days after sowing across a sowing sequence from 1 October to 19 November at weekly intervals. Pathogen recovery from stored seed, checked monthly for six months, was 19.6 per cent at 10 °C and 13.8 per cent at 20 °C before the next sowing, with none at room temperature on agar plates. A PCR assay set a detection limit of 10 g of seed at 30 per cent silique infestation and 1 g at 65 per cent.

Three consequences follow. A seed lot is not a neutral input — its disease history is measurable and partly testable. Cool storage is not automatically safer than ambient storage for seed-borne Alternaria. And because much of the inoculum that devastates a crop in February arrives by wind and rain splash as the season advances, a seed treatment can only be expected to protect the young plant.

Trichoderma as a Seed Treatment Against Alternaria Blight

The clearest seed-applied evidence against Alternaria blight under Indian field conditions is biological. C. Zotinkhuma, Akshita Gupta, Pratibha Sharma and colleagues at DAV University, Jalandhar, with co-authors from Amity University, tested biochar and Trichoderma seed priming on B. juncea variety PBR 91 in rabi 2024–25, in a randomised block design with ten treatments, reporting in the International Journal of Research in Agronomy in 2025.

The best treatment combined the recommended dose of fertiliser with a seed priming mixture of Trichoderma viride and T. harzianum at 50:50. It cut the days to 50 per cent germination to 4.50, gave 208.93 cm plant height at 90 days and flowering at 61.50 days, and produced 668.16 g of seed per plot. It delayed the first appearance of Alternaria blight to 83 days after sowing and gave the lowest incidence (48.29 per cent), severity (21.09 per cent) and area under the disease progress curve (447.51) in the trial; the control, fertiliser alone, recorded 54.54 per cent incidence, 29.12 per cent severity and an AUDPC of 716.40.

The honest reading is a real but partial effect: a 21 per cent severity figure alongside a 48 per cent incidence figure describes a crop that still has a great deal of disease in it. Trichoderma seed treatment shifts the epidemic curve and buys the crop time; it does not replace the spray decision. It must also be handled as a living product, since a live fungal antagonist and a fungicide on the same seed have to be paired carefully — benzimidazole fungicides and wild-type Trichoderma are not compatible partners.

Early Vigour: What Priming Reliably Delivers

Where seed treatment in mustard is unambiguously reliable is establishment. Karantothu Suresh, Raj Kumar Mandal and colleagues at Dr. Rajendra Prasad Central Agricultural University, Pusa, Samastipur, compared an untreated control with nine priming treatments on variety Rajendra Suflam in a laboratory study in rabi 2023.

Laboratory: germination and vigour indices

Reporting in Plant Archives in 2025, they found 1 per cent KH2PO4 for four hours the best of the set. Germination was 94.01 per cent against 82.49 per cent in the control. Time to radicle emergence fell from 48.00 to 42.00 hours, shoot length rose from 5.16 to 6.47 cm and root length from 8.17 to 9.91 cm. Vigour index I rose from 1101.37 to 1539.93 and the accelerated ageing score from 14.99 to 20.00, with amylase, peroxidase and catalase activity all rising sharply. Priming moves the seed's germination machinery into a higher gear before sowing.

Field: does it survive to harvest?

The two-year trial run by Rupa Das, Saikat Biswas and Amitava Dutta at Bidhan Chandra Krishi Viswavidyalaya, Kalyani, in West Bengal, in the winters of 2017–18 and 2018–19, is the clearest available answer, though it was not run in Rajasthan or Madhya Pradesh. Six genotypes were sown at 6 kg per hectare after priming with 0.15 mol KH2PO4, 0.1 mol KNO3, PEG 6000, distilled water or nothing. Pooled across genotypes, KH2PO4 gave 1781.9 kg per hectare, PEG 6000 1693.8 kg, KNO3 1565.4 kg and unprimed seed 1140.3 kg, and primed crops flowered and matured slightly earlier. Genotype mattered as much as treatment, and a West Bengal winter is not a Rajasthan winter — but the direction of the priming effect held across two seasons and six genotypes.

The Cost Arithmetic on Four or Five Kilograms of Seed

Everything follows from the seed rate. At four to five kilograms per hectare, a dressing at 2.5 g per kg costs the price of 10–12.5 g of product; a metalaxyl-M dressing at 3.5 ml per kg comes to roughly 14–18 ml of formulated product. Against the cost of a single field operation, the material cost of treating mustard seed is close to negligible. The real costs are the labour and care of dressing properly, and the requirement that treated seed be sown in the season it was treated.

Expectation, not affordability, is therefore the live question. Jai Narain Singh, Ashish Kumar and A. K. Chaubey, of Krishi Vigyan Kendra, Singrauli, under Jawaharlal Nehru Krishi Vishwa Vidyalaya, ran three seasons of on-farm trials in Gopalpur and Chorgahi villages of Sidhi district, Madhya Pradesh. Their best module — a 5 per cent aqueous garlic bulb extract seed treatment, one spray of the same extract at 45 days after sowing and one mancozeb 75 per cent WP spray at 2.5 g per litre at 75 days — cut disease severity by an average of 71.90 per cent, raised yield by an average of 37.30 per cent and returned a benefit–cost ratio of 2.56, as reported in the Environment Conservation Journal in 2022. All three modules tested beat the farmers' existing practice.

What This Means for Seed Companies and Growers

For a seed company, the conclusions are about labelling and about the lot rather than the bag. Mustard seed sold as treated should say what the treatment is for; a dressing aimed at Albugo candida should not be presented as Alternaria control. Where a biological is included, its compatibility with the chemical component matters as much as its dose, and the layered coating approach — separating chemical and biological inputs so they do not sit against one another — is the technical answer. ICAR–Indian Institute of Oilseeds Research, Rajendranagar, has published work on such a system in oilseeds: a biopolymer double-layer coating carrying a fungicide, Trichoderma harzianum Th4d and a crop-specific biofertiliser, with germination after storage of 78.8–86.7 per cent against 56–58 per cent untreated, and, in groundnut field trials, an 80 per cent reduction in stem rot and 21.1 q per hectare against 12.9 q per hectare.

That work is the technical basis of Seed Primer, the multilayer biopolymer coating Yaduka Agrotech supplies. Its published validation is in groundnut, sesame and soybean; there is no published mustard trial of the system, and no mustard claim is made for it here. For the grower, four decisions follow. Treat mustard seed before sowing; it is cheap and standard. Choose the treatment for the disease seed treatment can reach, which in mustard means white rust and seedling establishment ahead of Alternaria blight. Know the seed lot, because seed-borne Alternaria is real, measurable and more likely to survive cool storage than ambient. And keep the spray decision for Alternaria blight in the plan from the start, because no seed dressing has yet been shown to carry an Indian mustard crop through a high-pressure season on its own.

Conclusion

Mustard seed treatment in Rajasthan and Madhya Pradesh is a cheap, well-established and useful practice that is routinely asked to do one job too many. The evidence supports it strongly for white rust, where metalaxyl and other dressings act on a seed-borne oomycete, and for early vigour, where priming with KH2PO4 or KNO3 consistently improves germination, root and shoot growth, vigour indices and field establishment. It supports it meaningfully but partially for Alternaria blight, where a Trichoderma seed treatment delays the epidemic and lowers severity without controlling the disease, and where the recommended Indian practice remains a mancozeb spray programme from about 40 days after sowing. A mean percent disease index of 37.20 per cent across 24 locations in Morena, Bhind and Gwalior, and a pathogen recoverable from seed stored through the off-season, make the case for treating the seed and testing the lot — not for expecting the seed to settle the season.

References and Sources

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