A grower representative predicts Environmental Court rulings on disputed parts of the Manawatu-Whanganui regional plan could force some out of the industry.
Federated Farmers and Horticulture New Zealand have lodged appeals in the High Court, challenging the rulings on the council's One Plan.
The Environment Court rulings mean that all intensive farming and horticulture operations will need resource consents that will require nutrient management plans and nitrogen caps to reduce to reduce fertiliser and other nutrients entering waterways.
There are also more stringent rules on hill country erosion control and protecting biodiversity.
Tararua Growers' Association president Terry Olsen says if the basis for the rulings stands uncontested or survives an appeal, the extra costs and uncertainty of getting consents will restrict the way growers can operate and could force some to give up.
"The way we see it at the moment, it's going to add more cost to grower activities, it's going to prohibit some growing activities and it's also going to really restrict where the growing activity potentially can take place in geographical terms.
"Further along the supply chain, it could mean a decline in grower activity on the rural areas."
Mr Olsen says that will lead to job losses and affect the regional and wider economy.
Horticulture New Zealand is appealing on behalf of the region's 200 growers. Chief executive Peter Silcock says one of the biggest worries for them is whether the Environment Court rulings could restrict essential crop rotation practices.
Hew Dalrymple, a Federated Farmers grain and seed representative, says it believes the Environment Court has gone too far and the appeal is partly aimed at getting some legal clarity.