Rust fungus was released in summer 2024 in Hertfordshire by Herts and Middlesex Wildlife Trust and in West Yorkshire.
Additional Defra funding has also seen a “successful” release at Wheldrake Ings nature reserve near York, the trust said.
The National Trust, which runs Hardcastle Crags, Hebden Bridge, said it was “delighted” that rust fungus was “thriving” there.
Rosie Holdsworth, National Trust countryside manager, said early results had been “very encouraging”.
“We’re excited to monitor how the fungus continues to suppress balsam growth in the coming seasons,” she said.
Elliot Baxendale, YWT project officer, said the charity had spent around 700 hours across two months in 2025 manually removing it.
“We spend a lot of time managing Himalayan balsam infestations both on and off our reserves,” he said.
“It’s a difficult task given its sheer quantity and how hard it is to reach.”
The rust fungus survived the Yorkshire winter, YWT said, and in spring it “naturally reinfected” this year’s Himalayan balsam seedlings.
Mr Baxendale said it was “a truly exciting and game-changing opportunity for managing this highly invasive and destructive species”.