Some farmers say they fear their families could be put at risk of coronavirus due to an increase in walkers using footpaths on their land.
Under official guidance people can go for a walk or run close to home once a day.
But some farmers say paths should be closed or diverted because of fears it could be spread unwittingly via stiles and gates.
The Welsh Government said it had already shut some of the busiest paths.
This includes popular paths in Snowdonia and the Breacon Beacons, where crowds flocked for exercise at the start of the restrictions, despite social-distancing warnings.
Residents are urged to be responsible whilst out on public footpaths and fields for their daily exercise. We have had reports of walkers not adhering to the government guidance or social distancing and social gatherings. 1/3 pic.twitter.com/YxKMC3Ec0m— Bridgend CB Council (@BridgendCBC) April 2, 2020
Jacob Anthony, who farms near Bridgend, said he had seen a significant increase in walkers coming through his farmland since the measures were introduced.
He said while he usually enjoyed speaking to walkers on his land he was worried they may be unknowingly spreading the virus, and worried it could harm his loved ones, and the livestock, especially during the lambing season.
"My grandad is 87, is still farming, my sister is asthmatic and my mother has an auto-immune disease and we really don't want to be catching this virus," he said.
"We've seen some motorbikes and families with young children as well as beer cans on the mountains so it looks like people have been drinking up here too," he said.
"Farmers can't go into hibernation, we have to work, and the countryside is our office.
"If we're sick there's nobody to look after the animals."
Kate Beavan, a farmer near Abergavenny, said while she appreciated how lucky she was to have so much outdoor space, when some people were stuck inside without gardens, people needed to think before they ventured to the countryside.
"Walkers will be welcomed back here with open arms when this craziness is over, we are just asking for a bit of thought for vulnerable farming families at this time. I think the majority of people are understanding," she said.
The National Farmers' Union (NFU) in Wales said there had been a "significant increase" in people using paths, and called on the Welsh Government to act.
NFU Cymru's Hedd Pugh said he found a walker from Shrewsbury on his farmland, near Dinas Mawddwy, Gwynedd, who was unaware of the guidance to stay close to home to exercise.
"Farmers have observed a significant increase in the use of public rights of way and access land in the light of the social distancing guidelines introduced during the Covid-19 pandemic.
"This has led to concerns and anxiety where public rights of way are in close proximity to homes and farmyards, particularly so in instances where farmers or members of their families fall into the vulnerable category.
The Welsh Government said it had introduced regulations forcing councils, National Park Authorities, Natural Resources Wales and the National Trust to close certain footpaths.
"The busiest locations, where large numbers of people gather, have been closed," he said.
"The regulations also allow the closure of paths if their use poses a high risk to the incidence or spread of infection in their areas.
"The decision on closing paths rests with these authorities as they possess the local knowledge to understand where a closure is necessary."
The Welsh Conservatives' rural affairs spokesman Andrew RT Davies said some footpaths crossed people's homes and gardens.
"Families and farmers are both telling me they are getting scared that an influx of people - in some cases more than they've seen before - could spread this virus to them," he said.
The UK's largest walkers' group, The Ramblers, said it has asked people to respect the closures.
"We have joined with other prominent outdoor organisations in writing to the Welsh Government urging them to keep a focus on helping people to safely access local exercise opportunities near to their homes, while also guarding against unnecessary or inappropriate path and green space closures," it said.