Experts fear an African swine fever (ASF) outbreak in Britain’s wild boar population – as they feast on dumped pumpkins.
The virus has already killed millions of pigs and wild boar worldwide, and can be traced to kitchen scraps and waste.
ASF can survive in cooked, frozen and preserved pork products.
These products can be cross-contaminated with other foods, including pumpkins.
Gloucestershire Constabulary's Rural Crime Team tweeted: "Please do NOT dump old pumpkins out in the woods/car parks in the Forest of Dean.
"There has been a large amount of Jack-o-lanterns dumped for the wildlife to feed on – but please remember it's illegal to feed the boar."
The force also shared a government warning over feeding wild boar in the region, saying that the arrival of ASF in Britain would be "devastating".
The guidance reads: "It is illegal to feed pigs, wild boar or any livestock with catering waste or kitchen scraps due to the risk of the disease.
"Ensure you dispose of any food leftovers in a secure bin.
"The most likely way ASF could infect pigs or wild boar in the UK is if they eat pork or wild boar meat products from infected animals.
"This could happen if a member of the public brought produce back to the UK from affected countries in Europe, Asia or Africa.
"It can also be spread on contaminated clothing, footwear and vehicles."
Foresty England previously said: "The disease can survive in cooked, frozen and preserved pork products and cross-contamination can occur with foods that are prepared in a domestic or catering kitchen.
"If food that has been contaminated is then fed to a pig or boar, either deliberately or accidentally, the impacts will be devastating to the boar and domestic pig population."
Wild boars have divided opinion in the Forest of Dean for years, with some arguing they are part of the region's history.
But others point to the chaos and destruction they can cause – with reports of attacks on pets and dog walkers.
Some locals have even claimed that the pigs have learned when bin day is so they can come into urban areas and rummage for food.