Climate change, driven by rising global temperatures, means apple and pear producers in traditional growing regions are facing greater extremes in weather from summer drought to increased winter rainfall. Rising global temperatures have resulted in earlier springs and longer, hotter summers, increasing water uptake in apple and pear crops and putting pressure on vital water resources.
Since the late 1800s global temperatures have risen by an average of 0.5°C - 0.7°C and forecasts suggest that trend will accelerate. Increases of 0.2°C are expected every 10 years over the next century and that could have severe implications for tree fruit growers.
Orchards, particularly intensive production, require an adequate water supply during the growing season but it becomes more critical for yield and quality in the spring and summer. It is during this stage of the production cycle that the fruit moves from growth driven by cell division to increasing size through fruit cell expansion. This fruit fill is heavily dependent on water supply and it coincides with a seasonal period when water is most likely to be scarce.
As well as the reduced rainfall during the summer, drier, hotter weather increases the heat load on the tree. This adds to the rate of evaporative loss from the leaves and more water is drawn up from the soil as the process of transpiration accelerates. Evaporative losses also occur from the soil surface removing more moisture from the area around the roots, where it is needed most.