The New Zealand Winegrowers website explains their Sustainability policy so well:
The Maori word Toitū (pron. toy-TOO) refers to the life-force of the land and can be interpreted as meaning "eternally sustainable”. For us it represents the New Zealand wine industry’s commitment to protect the places that make our famous wines, and to ensure that our activities lead to continually improving economic, environmental and social outcomes, locally and globally.
Under New Zealand Winegrowers’ Sustainability Policy, wine must be made from 100% certified grapes in fully certified winemaking facilities and certification must be through an independently audited programme — either Sustainable Winegrowing New Zealand or one of the recognised organic or biodynamic certifications.