Dog mess has been tied to a gate lock in the popular tourist spot the Dedham Vale - an area of outstanding natural beauty on the Essex and Suffolk border.
Farmer Lucy Jane saw the mess smashed into the gate's combination lock near Flatford Mill, close to Willy Lott's Cottage on Tuesday while working with her 14-year-old son.
Describing the littering as "utterly vile," she cleaned it up so she could get to her sheep and open the combination padlock.
"People come to enjoy the countryside but it would be nice if they would respect it," Ms Jane said. "It was absolutely disgusting.
"Bags are also left hanging on trees and people say they'll pick them up on the way back but they don't."
Ms Jane also claims there has been sheep worrying in this field and the other one she has in Royal Hospital School in Holbrook, which is illegal under the Dogs (Protection of Livestock) Act 1953.
"They can have a heart attack and die," she added, explaining when she confronts dog walkers: "The majority of people are kind but you get several who say 'I do what I like when I like.'"
Recently, she asked a dog owner to move to a field in Flatford where you can leave your dogs off the lead and was told the sheep probably enjoy it.
"My sheep do not know what the dogs will do over the time they're chasing them," the 45-year-old said. "It's so heart-breaking.
"I really don't understand the mentality of it. I honestly do not know why.
"I’ve also had some metal fencing posts stolen and had someone use spray paint and put it on my sheep feeder," she said.
"Plus I had a knife left on one last year as well. I’m so fed up with it. Why can’t people enjoy the countryside and respect it as well?"
A spokesperson for the National Trust, who manages Dedham Vale, said: “Flatford is a very popular place for people to walk their dogs and we welcome responsible dog owners.
"Dog waste bins are available but we encourage all visitors to take their dog waste home with them and have placed signage around the site.
"We are promoting the countryside code and have a canine code of conduct, which we hope will promote responsible dog ownership.”
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