They will instead have to pay a tax to send the waste to landfill. However, the NFU has helped to secure a temporary extension of the old practice until 2013 to give growers a chance to adjust to the new rules.
An NFU representative said: "There are serious concerns on the financial impact this could have on tomato growers."
British Tomato Growers' Association chairman Nigel Bartle told Grower: "It's difficult to find a material that will last and that comes at the right price because tomatoes are a very long crop. Lots of people shred it and there are some growers who still burn haulm. That was not a problem until it emerged that there's a tiny level of plastic on the haulm."
He added: "In the grand scheme of things, the amount of string is minuscule, but trying to remove it would be an absolute nightmare. It would be nice if growers could get a tax break for most of the waste being green."
The new waste regulations do, however, have many benefits for growers because the government has agreed not to charge farmers and growers for registering everyday waste exemptions.
A waste exemption is a very specific type of-low risk waste handling operation that does not require a permit. Originally it had proposed to replace the exemptions with a system whereby farmers and growers are charged every three years. But lobbying from the NFU has helped to get the charges dropped.
The union argued that such proposals would impose yet more cost burdens on the industry, discourage recycling and ultimately result in farmers and growers sending more waste to landfill.
NFU environmental policy adviser Aarun Naik said: "We welcome the Government's decision not to charge farmers for registering everyday waste exemptions.
"The NFU has lobbied hard against these charges because their introduction could have resulted in more than £4m being taken out of the farming industry and into the pockets of the Environment Agency each year.
"Recycling and responsible management of waste must be not be discouraged by introducing more costs onto industry, especially in the current economic climate."
Under the new regulations, farmers will be expected to re-register - at no cost - their relevant exemptions every three years.