The Horowhenua Mayor says the person who set fire to the Foxton Racecourse is obviously disturbed.
The police are investigating the fifth suspicious fire in a month to strike the racecourse in the town of Foxton in Manawatu.
Late last month it was hit by a string of four suspicious fires in the space of 10 days.
The blaze, to which the fire service was called at 1am on Sunday, destroyed half of the racecourse's last remaining stable block.
No horses were in the 28 stable block at the time of the fire.
Mayor Brendan Duffy says the community has had enough, and he believes the person responsible needs help.
Mr Duffy says people in the Foxton community need to step forward if they know anything about the fires.
He says people are not coming forward with information as readily as he would like.