PEOPLE are being urged to root out killer weeds this summer.
Two, which have been found growing in Kirklees, are ragwort - which can kill animals - and Himalayan balsam, which kills native plants.
The RSPCA is urging people with horses or livestock to watch out for ragwort.
The yellow-flowered weed is a major cause of animal poisoning.
When animals eat the plant it causes irreversible damage to the liver and digestive system and they die slow, agonising deaths.
Yorkshire RSPCA inspector Dave Millard wants landowners to kill off ragwort - which produces 150,000 seeds.
He said: "There is no cure for ragwort poisoning. The only effective prevention is to eliminate the plants."
Weedkiller can be used and ragwort should then be dug out by the roots.
Himalayan balsam has been taking root in Hepworth.
Mrs Sandra Horn and husband Keith, of Uppergate, found the weed growing at Far Lane and Sally Wood. She told Kirklees Council, but she and a friend removed the weed at Far Lane themselves - filling 10 bags.
Himalayan balsam has a thick, hollow stem and purple or red-tinged branches.
It up to six feet tall, with pink, purple or white snapdragon- like flowers and oval, serrated leaves.
It flowers in sunny moist, grassy spots from early summer to early autumn.
It smothers native plants.
A Kirklees spokeswoman said staff had collected the bags and would strim the plants.
Next spring, they would treat the areas with chemicals, to kill any remaining seeds.
She urged people who saw such weeds to tell the council, rather than deal with them themselves.
Phone Ross Streetcare on 0800 731 8765.
Battle hots up
MPS have backed a drive to control ragwort.
Millions of pounds every year are already spent in the battle against ragwort.
Now, a code of practice is being drawn up as part of new measures in the Ragwort Control Bill, which cleared its Commons stages yesterday.
Ragwort is thought to kill about 500 horses every year.