Bt hybrid (Bollgard II event)
Sold under many brand names on one GEAC-approved event — protects against the bollworm complex; destroy stalks after harvest for pink bollworm.
Quick facts
- Crop
- Cotton
- Type
- Hybrid
- Season
- Kharif
- Maturity period
- 160–170 days
- Seed rate
- 4.0 kg per acre plus 1.0 kg of non-Bt seed for the refuge, which you sow around the Bt crop. The refuge is not optional — it is what keeps bollworm from beating the Bt toxin (PAU, north zone)
- Expected yield
- 18–22 q/ha (seed cotton)
- Suitable soil
- Clay / black soil
- Disease resistance
- Bollworm complex — not pink bollworm, which has developed resistance
- Release
- GEAC approval 2006 · event licensed from Mahyco Monsanto Biotech, sold by many companies under their own hybrid names
Actual yield depends on sowing time, soil, irrigation, weather, seed quality and crop management.
About this variety
"Bt hybrid (Bollgard II event)" is not one ICAR-released variety — it is a class of hybrids from many seed companies that all carry the same Bollgard II genetic event, licensed from Mahyco Monsanto Biotech and approved by India's Genetic Engineering Appraisal Committee (GEAC) for commercial release in 2006. The event stacks two Bt genes, Cry1Ac and Cry2Ab, in the cotton plant's own tissue, giving built-in protection against the bollworm complex (American, spotted and — originally — pink bollworm). ICAR-CICR, Nagpur has been the government's Bt Referral Laboratory since 2005, testing seed lots for the presence of the Cry genes.
Should you pick this variety?
Pick a Bt hybrid on the Bollgard II event if you farm irrigated cotton with assured inputs and American or spotted bollworm is your main pest. It takes 160–170 days and gives 18–22 q/ha of seed cotton, the highest of the cottons compared here. Two conditions come with it: sow the refuge — 5 border rows of non-Bt cotton or 20% of the field, whichever is more — and destroy the stalks right after the last picking, because pink bollworm has beaten this event since about 2015. Seed costs more and there is no protection at all against jassids, whitefly, thrips or mealybug. Choose LRA 5166 or Suraj if you want to save your own seed or farm with low inputs, and DCH-32 if the mill pays you for extra-long staple.
Sowing & cultivation
- Sowing time1 April to 15 May. Sowing in this window gives better yield and gets the crop ahead of the insect build-up. Sow in the morning or evening (PAU)
- Seed rate4.0 kg per acre plus 1.0 kg of non-Bt seed for the refuge, which you sow around the Bt crop. The refuge is not optional — it is what keeps bollworm from beating the Bt toxin (PAU, north zone)
- SpacingRows 67.5 cm apart, with plants thinned to 75 cm within the row for a Bt hybrid — far wider than the 30 cm a Bt variety gets, because a hybrid plant is much bigger
- Sowing methodSow in lines with a cotton drill or planter, and thin after the first irrigation or a heavy shower
- IrrigationFour to six irrigations depending on the rain. The first comes 4 to 6 weeks after sowing and the rest every two or three weeks. Never let the crop go short at flowering or boll formation (PAU)
- Fertilizer55 kg N and 12 kg P2O5 per acre for a Bt hybrid — 120 kg urea with 27 kg DAP or 75 kg single superphosphate. That is nearly twice the nitrogen a non-Bt variety takes. Skip the phosphorus if the crop follows a well-fertilised wheat (PAU)
Pest & disease considerations
Management notes
- Grow the mandatory refuge — 5 border rows of non-Bt cotton, or 20% of the field area, whichever is more — around every Bt hybrid block; this is the Government of India stewardship requirement, not optional
- Destroy and remove cotton stalks right after the last picking — pink bollworm overwinters in old stalks and unpicked bolls, and this is now the main defence since the pest developed resistance to Bollgard II by around 2015
Advantages & considerations
Why farmers may choose it
- Built-in protection against the bollworm complex reduces the number of sprays needed for that pest group specifically
- Wide choice of company hybrids on the same event, adapted to different regions and soils
Things to consider
- Pink bollworm resistance to Bollgard II is now widespread — the technology no longer reliably protects against this particular bollworm species, only the American and spotted bollworm
- Higher seed cost than a non-Bt hybrid or open-pollinated variety, and no built-in protection against sucking pests (jassids, whitefly, thrips, mealybug) at all
- Skipping the refuge requirement accelerates resistance development for everyone growing Bt cotton in the area, not just your own field
Suitable regions
States this variety is recommended for — check locally, since a state can have more than one recommended zone.
- Gujarat
- Maharashtra
- Telangana
- Andhra Pradesh
- Punjab
Pink bollworm: the one job Bt will not do for you
Bollgard II still protects against the bollworm complex, but pink bollworm resistance to it is now widespread. On that one pest the seed gives you nothing, and the pest survives from one season to the next inside your own field trash.
So the control is a calendar, not a spray can. Destroy and remove the stalks after the last picking instead of leaving them standing or stacked at the field edge, and do not keep the crop going for an extra late picking, because a long season is what builds the pest up. Sow within your area's window so the crop is not flowering late, hang pheromone traps to know when moths are about, open a few green bolls each week to look for pink larvae and rosetted flowers, and keep the refuge rows your seed packet asks for. These steps work much better when the whole village does them in the same weeks.
Where the planting material comes from
This is a hybrid, so seed kept from your own harvest will not breed true. The next crop comes up uneven in height, maturity and yield. Buy fresh certified seed every season and keep the bag tag until harvest.
How it compares with other varieties
Every Cotton variety with a page on this site, side by side. The row for this page is highlighted.
| Variety | Best for | Maturity | Yield | States |
|---|---|---|---|---|
| Bt hybrid (Bollgard II event)this page | Irrigated, high-input cotton where American bollworm is the main pest | 160–170 days | 18–22 q/ha (seed cotton) | Gujarat, Maharashtra, Telangana, Andhra Pradesh, Punjab |
| DCH-32 (hybrid) | Extra-long staple cotton under assured irrigation in south India | 170–180 days | 10–15 q/ha seed cotton | Karnataka, Tamil Nadu, Andhra Pradesh, Maharashtra |
| LRA 5166 | Non-Bt long-staple cotton for seed saving and for the Bt refuge rows | 165–175 days | 12–15 q/ha (seed cotton) | Gujarat, Maharashtra |
| Suraj (desi, non-Bt) | Low-input desi cotton for dry, sandy north-west land | 150–160 days | 8–10 q/ha, stable under stress | Punjab, Haryana, Rajasthan |
Tools for this crop
The numbers you need next: how much seed to buy, whether the lot germinates, what the fertilizer bill looks like and what Cotton is selling for.
- Seed Rate CalculatorHow much seed your Cotton plot needs, corrected for the germination of the lot you bought.
- Germination CalculatorTest 100 seeds from the bag before sowing and see whether the lot is fit to sow.
- Seed Variety FinderFilter every Cotton variety on this site by state, season, duration and soil.
- Fertilizer CalculatorTurn the NPK recommendation for Cotton into bags of urea, DAP and MOP for your field size.
- Crop CalendarMonth-by-month sowing, weeding, irrigation and harvest dates for Cotton in your state.
- Crop Profit CalculatorPut your seed, labour and input costs against the yield you expect from this variety.
- Mandi Price CheckerToday's Cotton rate in your nearest mandi, before you fix a price with a trader.
Frequently asked questions
Is Bt cotton the same in every company’s hybrid?
The underlying genetic event (Bollgard II, carrying Cry1Ac and Cry2Ab) is usually the same, licensed from Mahyco Monsanto Biotech — but it is bred into different parent lines by different companies, so agronomic traits like duration, canopy and regional suitability vary by brand.
Does Bt cotton still protect against pink bollworm?
Not reliably. Field-level resistance to Bollgard II was first reported by CICR around 2015, driven largely by inadequate refuge planting — stalk destruction after harvest and refuge compliance now matter more than the Bt trait itself for this pest.
How much refuge area does Bt cotton need?
5 border rows of non-Bt cotton, or 20% of the total field area, whichever is more — this is the Government of India stewardship requirement for every Bt hybrid.
Bt hybrid or non-Bt LRA 5166: which should I sow?
A Bt hybrid gives 18–22 q/ha but costs more in seed, needs the refuge rows and still needs sprays for sucking pests. LRA 5166 is non-Bt and open-pollinated, gives 12–15 q/ha, lets you save seed and also serves as your refuge crop. If your irrigation and inputs are assured, the Bt hybrid pays; if not, LRA 5166 is the steadier bet.
Can I keep seed from a Bt hybrid for next year?
No. It is a hybrid, so the next generation separates out and the crop becomes uneven, and the Bt trait is licensed technology. Buy fresh seed every season and keep the bill, which is also your proof if a seed lot fails.
What should I spray on Bt cotton, if the bollworm is already covered?
Plan for the sucking pests — jassids, whitefly, thrips and mealybug — because the Bt trait does nothing against them. Also keep watching for pink bollworm, which now survives on Bollgard II, and treat stalk destruction after picking as part of the plan, not an extra job.
How long does a Bt hybrid hold the field?
160–170 days, and with pickings spread over weeks the field is often tied up longer than that. Decide the rabi crop before you sow, because cotton that is still carrying bolls in December is what pushes wheat into a late sowing.
What seed-cotton yield should I plan for from a Bt hybrid?
18–22 q/ha of seed cotton, against 12–15 q/ha for the non-Bt variety LRA 5166 and 10–15 q/ha for DCH-32. That gap assumes irrigation and a full input schedule. On dry, low-input land the hybrid's advantage shrinks fast.
Sourced from: Package of Practices for Kharif Crops, Punjab Agricultural University: cotton sowing window, seed rate with refuge for Bt hybrids, row and plant spacing by cotton type, fertiliser and irrigation. editorial policy.