Pesticide Action Network Updates Service (PANUPS)

U.S. Town Uses Hot Water to Control Weeds

June 14, 1999

Carrboro, North Carolina, is killing weeds with water instead of chemicals. The town is using a machine that superheats water and dispenses it in a carefully controlled stream to kill weeds without using toxic chemical herbicides. The equipment, which is made in New Zealand, is in use in several other countries but is almost unknown in the United States.

Carrboro is testing the equipment to implement the town’s least toxic Integrated Pest Management policy, adopted in March 1999. The policy calls for phasing out use of conventional pesticides, including herbicides, on town property, but does not apply to the local residents, their property or businesses. City leaders hope to show how beautiful grounds can be achieved without poisoning the environment.

To date, efforts to reduce pesticide use have emphasized alternatives to conventional herbicides. An earlier analysis of Carrboro’s pest management practices showed that more pesticides were used on weeds than for any other purpose. Weeds are a problem around buildings and parking lots, along curbs and gutters and in parks. The town is using a comprehensive approach, rather seeking a single solution, including a biodegradable herbicide made from corn gluten, propane flamers which kill plants by singing them, thick mulch on plant beds to smother weeds, and now hot water.

The machine in use in Carrboro produces a steady stream of near-boiling water that kills weeds by melting the waxy outer coating of their leaves. The self-contained machine is mounted on a small truck with hoses connected to long-handled applicator wands. A quick spray on unwanted weeds kills them; the plants darken almost immediately and turn brown within a few hours. The flow of water is low and cools quickly. While the results look very much like that of a contact herbicide, there is no toxic residue and the area is immediately safe for play.

“That’s what it is all about,” said Allen Spalt, Director of the Agricultural Resources Center and a member of the Carrboro Board of Aldermen. “We want to find ways to reduce pesticide use so that we can eliminate the risk of any child being poisoned. Carrboro already uses only small amounts of pesticides; we believe that this hot water system may be part of the solution to reducing use completely.”

The hot water system, on loan to Carrboro until the end of June, will be used by town staff, who will also demonstrate it for other interested parties. At the conclusion of the trials, a final decision will be made whether or not the town will purchase the equipment.

Source/contact: Allen Spalt, Director, Agricultural Resources Center, PESTicide EDucation project, 115 West Main Street, Carrboro, North Carolina 27510; phone (919) 967-1886; fax (919) 933-4465; email: aspalt@mindspring.com; Web site http://metalab.unc.edu/arc/