Officials at the Peak District park are hoping volunteers will help staff eradicate a plant which is being blamed for damaging riverbanks.
The non-native Himalayan balsam is said to have a "devastating impact" by over-running natural species and causing erosion.
Park officials fear that if the plant is left unchecked it could threaten the area's biodiversity.
Work to clear part of the River Dove starts on 2 June at Hulme End car park.
National park ecologist Frances Horsford said: "We need to get rid of it in June, July and August before it seeds.
"Each plant produces up to 800 seeds in pods that 'explode' on touch, catapulting the seed up to seven metres.
"But, in the autumn it dies back leaving bare banks.
"We'd be very grateful for people's help before it's too late."
Volunteer are sought on the River Derwent between 1000 BST until 15000 BST on Sunday 11 July, Saturday 17 July and Sunday 25 July.
People should meet near Calver crossroads on the A623 by the playing fields, officials said.