Bollgard Turns 30: Bt Cotton's Path From 'Triple Nickel' to 2029 Launch

Bollgard, the Bt worm-resistance trait that broke tobacco budworm's grip on the Cotton Belt, marks 30 years since its 1996 commercial release — and its maker already has a successor, Bollgard 4 HT4 with ThryvOn, targeted for launch by 2029.

In the late 1980s and early 1990s, tobacco budworm turned uncontrollable across the Cotton Belt. The bioengineered Bt trait supplied the fix, and Bayer's Bollgard franchise grew from it.

Jay Mahaffey, entomologist, Scott Learning Center manager and science fellow at Bayer Crop Science in Scott, Miss., has studied Bt traits since graduate school — before the technology had a name. He has spent 32 years as an entomologist at the center.

Mahaffey said Bollgard technology seemed like science fiction at the time. "It was the idea that genes from bacteria could be expressed to produce protein in plants. That's what became the Bollgard franchise of products," he explained.

What did Bollgard change?

Mahaffey credits Bollgard, alongside boll weevil eradication, with building a cotton pest management system growers had never experienced.

"It allowed changes in varieties and technologies that made a serious positive contribution to our pest management system," he said.

Before Bt, farmers planted conventional upland varieties across the southern Cotton Belt — Deltapine 50, Deltapine 20, Sure-Grow 125 and Sure-Grow 501.

"The cotton world, in a search for earliness, had started to grow varieties that were determinate and earlier," Mahaffey said. "They taught us a lot about what we could or couldn't do with insect management. Those are varieties that a lot of folks remember."

Which varieties defined the shift?

The move from conventional to Bollgard genetics produced milestone releases:

• 2003: Deltapine 555 BG/RR, the "triple nickel," which Mahaffey called a "major breakthrough" — enabling fruit retention on more nodes and fuller season-length exploitation.
• 2005: Bollgard II reached the market.
• 2016 class: Deltapine 1646 became the most planted variety, covering the largest percentage of cotton acreage in modern times.

"Everybody remembers 'triple nickel,'" Mahaffey said. "We enabled an insect management system that let us exploit season length to the ultimate goal of increased fruit retention."

Deltapine now evaluates a new variety set every year through its New Product Evaluator program, running for nearly 20 years. Bollgard 3 and ThryvOn technology have since reached growers.

What's coming in the 2025 class and beyond?

Mahaffey flags two 2025-class varieties. Deltapine 2537 BT3XF is broadly adapted and high-yielding in the Midsouth and upper Southeast. Deltapine 2522NR B3TXF adds reniform nematode tolerance and a full trait package: Bollgard 3 for worms, ThryvOn for plant bugs and XtendFlex triple-stack herbicide protection.

"We've reduced another stressor in the system like reniform nematodes. It all really started, in my view, with Bollgard," Mahaffey said of Deltapine 2522. "It has enabled us to develop less determinate genetics, put those genetics in the marketplace and give people guidance about how to use [plant growth regulators] as good as they can be."

Bollgard 4 HT4 with ThryvOn is expected to launch by 2029, extending the trait line another generation.