The U.S. Consumer Product Safety Commission said the failed welding can cause loss of control of the mowers, raising the risk of a crash. No incidents or injuries had been reported, the agency said.
The recall involves 2011 zero-radius-turn riding mowers with red, welded tubular steel frames. They were sold with three deck sizes: 44, 48 and 52 inches.
The recalled mowers are steered with two hand-held levers, rather than steering wheels.
The recall involves mowers with model number PNS20KA443 and serial numbers 928367 through 947833; model number PNS22KA483 with serial numbers 928417 through 949985; and model number PNS24KA523 with serial numbers 928492 through 950315.
They were sold nationwide by Exmark dealers last month and in March for between $6,881 and $7,658.
Consumers were advised to contact an Exmark dealer to have welded parts replaced.
Consumers can call 800-667-5296 for information.