Climate warming is leading to higher water use by fruit trees. Longer vegetation periods, higher evapotranspiration (ET) and extended droughts are the key factors. This study investigated, if supplementary irrigation of ‘Red Topaz’ ( Malus × domestica ) trees is required in South-West Germany. From 2023 to 2025 four irrigation strategies were applied: a digital sensor-based irrigation at a soil water tension threshold of 30 kPa, a web-based soil water balance irrigation model at an available wat