Some of the UK's favourite fresh foods may be unavailable for weeks, or even months, if the country crashes out of the European Union without a deal, the UK's food and drink lobby warned on Wednesday.
Retailers such as Tesco have also warned that leaving the bloc on October 31 without a transition agreement would be problematic because so much fresh produce is imported and warehouses are stocked full before Christmas.
The industry - which employs 450,000 people - views Brexit as the biggest challenge since World War II, dwarfing previous crises such as the horsemeat scandal of 2013 and the mad cow disease outbreaks of the 1980s and 1990s.
"We know there will be disruption at ports, and that will have knock-on effects," Tim Rycroft, the Food and Drink Federation's chief operating officer, told Al Jazeera.
"There will be shortages - [though] no one will starve; this won't be like the war."
The UK only produces half the food it consumes, and retailers are concerned food with short shelf-lives could be left to rot in the back of trucks while lengthy new customs procedures build backlogs of deliveries.
In advance of the original Brexit deadline of March 29, supermarkets and retailers spent millions of pounds working with suppliers to increase stocks of dried goods including pasta, bottled water and toilet paper.
But after three years of Brexit discussions, it is still unclear on what terms the country will leave the bloc, with options ranging from a last-minute exit deal or delay to an acrimonious divorce.
Prime Minister Boris Johnson has repeatedly said that unless the EU agrees to a new divorce deal, he would then lead the country out of the bloc on October 31 without an agreement.
When winter approaches, the UK becomes more dependent on imported food, so a Halloween no-deal Brexit is potentially more disruptive.
Britain imports around 60 percent of its food by the beginning of November - just the time that delays caused by a no-deal Brexit could be clogging up ports and motorways, Rycroft said.
Fresh fruit and vegetables, which have a short shelf-life of only a few days, cannot be stored for long so any checks at Calais could lead to significant disruption at Dover, Britain's biggest port.
The cost of preparing for a no-deal exit, including reserving warehouse space, using alternative distributors and losing orders in congested ports, would cost the industry up to 100 million British pounds ($121m) a week, Rycroft earlier told Reuters News Agency.
A government spokeswoman said it was working to support industry: "The UK will be leaving the EU on 31 October and our top priority is supporting consumers and businesses in their preparations for Brexit."
The UK food and drink industry accounts for 19 percent of the manufacturing sector by turnover and employs more than 450,000 people in Britain across 7,000 businesses including Associated British Foods Plc, Nestle and PepsiCo.
Some of the bigger companies have tested different ports to avoid the main route of Dover-Calais while pharmaceutical companies have reserved air freight capacity to fly in supplies if needed.
Brexit supporters say there may be short-term disruption from a no-deal exit but that the UK will thrive if cut free from what they see as a doomed experiment in integration that has led to Europe falling behind China and the United States.
Rolls-Royce said on Tuesday it was ready to cope with the fallout from a disorderly Brexit after the aero-engine maker spent around $120m to increase inventory, among other preparations.
We now need government to follow through and manage some of these consequences
Tim Rycroft, UK Food and Drink Federation
Concerns over a no-deal Brexit are being raised in other sectors, too.
University research faces the triple threat of reduced tuition-fee income, the loss of EU grants and post-Brexit visa difficulties for researchers, the Lords Science and Technology Select Committee has warned, urging ministers to match EU levels of research funding after the UK leaves the bloc to protect university income streams.
As the UK is a net beneficiary of EU research funding, this amount will be greater than the amount the UK currently contributes to the bloc's research pot.
"The government intends to spend 2.4 percent of GDP on research and development by 2027," said committee chair Lord Patel. "But we conclude that it will be extremely difficult to meet this target unless funding for research in universities is secured and the UK can attract researchers from overseas."
Delivery truck drivers also face the "absolutely outrageous" scenario of sitting in two-day-long queues without food or toilets if the UK crashes out of the EU, hauliers have warned.
"I think people under-estimate the scale of the complexity of it," said Duncan Buchanan, policy director for the Road Haulage Association.
"I believe the reasonable best-case scenario that authorities are working on is between 24- and 48-hour delays on all vehicles - all vehicles, all lorries going through the port."
And no welfare provisions are being put in place for the drivers, he said.
"We have huge road delays. We have serious problems. If a lorry is caught up 24 hours on the motorway, where does the driver go to the toilet? This is absolutely outrageous that drivers can be treated like they're completely unimportant.
The UK has 85 days to sort out these issues before the country leaves the EU by automatic operation of law on October 31.
"We now need government to follow through and manage some of these consequences," Rycroft told Al Jazeera.