Fruit and vegetable growers are battling to stop people stealing their produce.

Thefts are costing growers tens of thousands of dollars each year, with broccoli, corn, watermelon and avocados among the most popular crops.

Horticulture New Zealand reports cases of entire potato and onion plots being dug up overnight, or apple and avocado trees being stripped by thieves.

Growers have started to beef up patrols and some are considering closed circuit television surveillance.

Grower and packing firm Leaderbrand Produce of Gisborne estimates it loses thousands of dollars every year in stolen produce.  Operations manager Stuart Davis believes most is then sold illegally at flea markets.