For cherry producers, the accumulation of chill hours during winter is an essential pillar to ensure even and productive bud burst. In recent seasons, it has become evident that winters are losing consistency: there are fewer cold days, more cloudiness during certain periods, and increasingly frequent warm afternoons in the middle of winter. These conditions can compromise chill accumulation, leading to uneven bud bursts, late bloomings, and a direct impact on the productive and commercial potential of the orchards.
In this scenario, alongside climate monitoring, new agronomic tools emerge to protect the already accumulated chill. One of these is the controlled use of water to cool the orchard during warm winter events, a technique that has already shown positive results in areas like Maule and Biobío. Its objective is not to generate cold, but to prevent the loss of what has already been gained, especially during the dormancy phase.
How does water cool? The principle of evaporative cooling
This technique is based on evaporative cooling, a physical process wherein water, as it evaporates, absorbs heat from the environment. By applying small amounts of water using pulsators or micro-sprinklers on the canopy, a thin film is formed which, when evaporating, reduces the temperature of the air and nearby plant tissues.
The system is activated in a timely and strategic manner, with the aim to prevent ambient temperature from exceeding 14°C, a critical threshold identified for its potential to reverse already accumulated chill hours. Therefore, it is recommended to start the application between 12 and 13°C, anticipating the thermal rise to keep the environment under control and avoid reaching the risk threshold.
The protocol is implemented through a block logic:
Water is applied for 30 minutes at an intensity of 1 mm/h.
Then, spraying is halted for 90 minutes.
If at the end of the interval the temperature continues to rise, a new 30-minute block is repeated.
This intermittent application pattern allows for effective temperature modulation without saturating the soil or wasting water resources. It is crucial to note that this management begins when chill hour accumulation starts, which typically occurs from May, depending on the location and local conditions of the orchard.
Conclusion
The use of water as a tool to cool the orchard during winter represents an emerging strategy with great potential to tackle the effects of increasingly warm and variable winters. This technique offers an adaptive management alternative in the face of climate change, allowing anticipation of risk scenarios and protecting orchard yield from the earliest stage of the production cycle.
Furthermore, it is a technique of simple installation and operation, which does not require significant additional hydraulic investments, making it an especially attractive alternative for producers keen on implementing strategies that ensure good chill hour accumulation during the dormancy phase.
