Chana Sowing: Seed Treatment to Prevent Wilt

Chickpea wilt, called ukhta or ukheda rog by farmers, is a fungal disease caused by Fusarium oxysporum f. sp. ciceris. The fungus blocks the water-carrying vessels of the plant, so the plant droops and dries even when the soil is moist.

The fungus survives in soil and plant debris as tough resting spores (chlamydospores) for several years, and it also travels with infected seed. This is why the same fields wilt year after year, and why seed treatment plus crop rotation is needed rather than one spray.

Wilt is worse in light, sandy soils, at soil temperatures around 25°C, and when the crop faces moisture stress. Early sowing in warm soil raises the risk. Losses range from 10 to 100% depending on variety and conditions, according to a review of chickpea wilt research.

Wilt shows up as drooping plants in patches, first in seedlings and again at flowering and pod stage. Early wilt causes more loss than late wilt because the plant dies before it sets pods.

• Seedlings collapse and lie flat on the soil within 3 to 5 weeks of sowing.

• In older plants, leaves droop from the top, turn yellow and then dry, while the plant stays green-stemmed for a few days.

• Split the stem lengthwise near the base: brown to black streaks inside the stem (vascular browning) confirm Fusarium wilt.

• Roots look healthy from outside, unlike dry root rot where roots are black, brittle and rotted.

• Patches spread in the same part of the field each season.

Dry root rot and collar rot are often confused with wilt. Seed treatment with Trichoderma and a fungicide helps against all three, which is another reason not to skip it.

A complete chana seed treatment protects against disease and helps the crop fix nitrogen and take up phosphorus. It has up to four components.

Doses vary by formulation. Follow the product label and local agriculture officer advice.

Seed treatment follows the FIR order: Fungicide, then Insecticide, then Rhizobium. Chemicals applied after Rhizobium kill the bacteria, and the crop then forms few nodules.

Trichoderma needs special care. It is a living fungus, and carbendazim, a systemic fungicide, can suppress many Trichoderma strains. So choose one of two routes: a chemical fungicide followed by Rhizobium and PSB, or Trichoderma followed by Rhizobium and PSB. If you want both a chemical and Trichoderma, use a fungicide that the Trichoderma label says is compatible.

Research under the ICAR All India Coordinated Research Project on Chickpea has tested such combinations, for example Trichoderma harzianum with propineb, as reported in the AICRP Chickpea report 2021-22. Rhizobium and PSB are generally compatible with Trichoderma, so the bio-only route is simple for organic growers.

1. Take good seed of a wilt-resistant variety. Remove shrivelled, broken and discoloured seed.

2. Day before sowing: spread seed on a clean sheet or use a seed treatment drum. Sprinkle a little water so the dressing sticks.

3. Mix the fungicide at the label dose and roll the seed until every grain is evenly coated. Dry in shade. If you are using the bio-only route, mix Trichoderma viride biofungicide at this step instead.

4. If termites are a problem in your field, apply the label dose of a seed treatment insecticide approved for chickpea. Let it dry.

5. Morning of sowing: boil about 100 g jaggery in 1 litre of water and let it cool. Mix in the Rhizobium biofertilizer and the PSB biofertilizer at the label dose to make a slurry.

6. Pour the slurry over the seed and mix gently by hand. Do not rub hard, or the coating comes off.

7. Dry in shade for 20 to 30 minutes and sow the same day. Never leave treated seed in the sun, which kills the bacteria.

Wear gloves and a mask while handling chemical dressings, and never use leftover treated seed as food or animal feed.

Seed treatment reduces infection, but a susceptible variety sown in a sick field will still wilt. Choosing a resistant variety is the single biggest step.

Pusa Chickpea 20211 (Pusa Manav), released in December 2020 for Madhya Pradesh, Gujarat and Maharashtra, was bred for Fusarium wilt resistance using genomics-assisted breeding. According to CGIAR's report on Pusa Chickpea 20211, it gave a weighted mean yield of 2,392 kg per hectare under wilt stress and matures in about 108 days.

In central India, JG 11 and JAKI 9218 are widely grown wilt-tolerant desi varieties. Seed companies and state universities release new resistant lines regularly, and the ICAR coordinated project screens dozens of entries for wilt each year. Ask your KVK for the latest resistant variety notified for your state.

Wilt is controlled most reliably when seed treatment is combined with good field practices. No single step is enough in a field with a long wilt history.

• Crop rotation: keep at least three years between chickpea crops in wilt-sick fields; rotate with wheat, mustard or sorghum.

• Sowing date: avoid early October sowing in warm soil. A review of wilt studies found late October sowing reduced wilt incidence.

• Deep summer ploughing: exposes and dries infected debris in May and June.

• Soil application of Trichoderma: mix Trichoderma with well-rotted FYM, keep it moist in shade for about a week, then broadcast before sowing.

• Moisture: avoid moisture stress at flowering; one light irrigation before flowering helps where water is available.

• Field hygiene: pull out and burn wilted plants, and do not carry soil from sick fields on equipment.

Use 75 to 80 kg seed per hectare for small-seeded desi chana and 90 to 100 kg per hectare for large-seeded types, which is roughly 30 to 40 kg per acre. Sow in rows about 30 cm apart for desi types.

Chana fixes its own nitrogen once nodules form, so it needs only a starter dose of nitrogen. Phosphorus and sulphur matter more; SSP is a good basal choice because it supplies both. Seed treated with Rhizobium and PSB makes better use of this basal dose. A chana nutrition soil kit can be added at sowing where soils are low in organic matter.

Rhizobium matters most in fields where chana has not been grown for several years, or never, because the right bacteria are scarce in that soil. In such fields, untreated seed often shows few pink nodules and pale plants at 30 to 40 days. Pull up a few plants carefully at that stage and split the nodules: a pink or red inside means they are fixing nitrogen, while white or green nodules are not working.

Sow chana about 8 to 10 cm deep in light soils so the seed reaches moist soil, and a little shallower in heavy soils. Avoid heavy irrigation soon after sowing, which can cause seed rot and collar rot.

For dealers, seed treatment is a small-ticket item that farmers often skip because it is not on their list. Selling it as a per-acre pack with seed changes that.

Biofertilizers have a shelf life, so order close to the sowing season and store them in a cool, shaded place. For bulk and institutional orders of bio-agents and biofertilizers, Katyayani Organics supplies distributors across India.

Before sowing, pick a wilt-resistant variety, buy the fungicide or Trichoderma plus Rhizobium and PSB, and plan to treat seed a day ahead. Follow the FIR order, dry seed in shade and sow on time. Follow the product label and local agriculture officer advice for every dose.