The country's biggest wool exporter is urging growers to stop sending underweight bales to market, a practice it says costs the industry more than a million dollars a year.
New Zealand Wool Services International spokesman Malcolm Ching says an estimated 20% of bales are packed too light.
Mr Ching says lighter bales add unnecessary costs during transport, handling and storage, and use more wool packs.
The official greasy weight, which is the weight of wool that has not been cleaned, ranges from 100 to 200 kilograms a bale, but coarse wool should weigh between 160 and 200 kilos a bale.
Mr Ching said the industry started to notice the problem a few years ago, but for some reason it has become noticeably worse this season.
He said in tough economic times woolgrowers do not have money to burn, but that is effectively what they are doing.