While the plants are dormant in winter, snowfall doesn’t cause major issues. Cherry plants are highly resistant to low temperatures; they are naturally adapted to temperate and cold-temperate regions. The problems arise mainly in two cases: when temperatures are extremely cold, and when snowfall and cold temperatures occur as the vegetative organs begin to awaken and mobilize, as is the case in spring.
When is the likelihood of heavy snowfall highest?
Although the possibility of snowfall is concentrated in winter, it can extend beyond that period. Late snowfalls can occur when plants already have developed vegetative organs, when they are no longer dormant, and when they have buds and flowers. This is when low temperatures become a problem, as the organs become sensitive and can freeze.
In these cases, the control systems used in the Argentine Patagonia are primarily irrigation or micro-irrigation systems. However, if there’s significant snow accumulation, frost control cannot be effectively implemented.
How is an orchard managed during and after snowfall?
The management of the orchard doesn’t differ significantly from what happens when it rains. When it snows or rains, activities are limited or suspended until they can be resumed when weather and environmental conditions permit. The first step is to clear the snow.
More than the snowfall itself, I would say that the low temperatures are the most delicate issue. Here, temperatures can reach -15 degrees Celsius, with typical ranges between -7 and -12 degrees Celsius. When the ground freezes in winter, it restricts earth-moving activities. For example, if I need to plant and the ground is frozen, it’s not the ideal time, and I have to postpone until the ground defrosts or plant earlier or later.
If the surface freezes within the first few centimeters, it can be broken using a shovel or pickaxe, and work can continue. If the ground freezing is more extensive, machinery is used to break it up and create furrows, allowing winter work to proceed.
What happens if I plant under those conditions and the soil afterward freezes?
The moisture in the soil freezes, then it expands, and when it returns to liquid state, the roots are no longer in close contact with the soil particles. Therefore, watering is required to quickly reestablish that contact. Root freezing can also occur. However, cherry plants are resilient to both snowfall and cold temperatures.
Due to snow accumulation of up to 40 centimeters or more, it covers all types of vegetation. This attracts hares and rabbits, especially hares in the southern Patagonia, which feed on the stems above the snow surface. Thus, intensified hare control is necessary. While hare protectors are always present, they can be covered by snow during snowfall.
What are the main variables to consider in these circumstances?
Snow adds weight to branches and can cause them to break. If the snow freezes, the weight increases, raising the likelihood of breakage. Additionally, during frost control measures, the sprayed water can freeze, adding additional weight.
Wind, which is a common factor in Patagonia, also has various undesired effects on plant structure, formation, and branch breakage.
Because of these factors, cherry crops in Patagonia must necessarily be supported by wire structures to withstand the weight of snow, frost control measures, and to mitigate the effects of wind. All of this is essential for sound plant structure from a productivity standpoint.
What benefits do these climatic conditions offer for the fruit?
Regarding benefits, snowfall itself doesn’t bring any particular advantages; it does, however, lead to temporary inconveniences, such as suspending and postponing all operational tasks: pruning, soil work, and plantings.
The primary benefit isn’t from snowfall, but from the accumulation of chilling hours. Patagonia and cold regions provide the required chilling hours for plants to achieve a good production.
Moreover, the Patagonian environment, in addition to providing cold, also experiences longer days during spring and especially summer. This slows down and extends the phenological stages, resulting in better fruit quality. The thermal amplitude, the difference in temperature between day and night in Patagonia, means that the plant doesn’t have to tap into its sugar reserves, leading to higher sugar content or brix levels in the fruits.
Another benefit of an extremely cold environment like that of Patagonia is a healthful environment in terms of pests and diseases, as they are almost non-existent. This makes for a highly favorable environment from that perspective.
What can you tell us about other regions producing cherries under these conditions?
Many regions, particularly in the Northern Hemisphere, produce cherries with snow. It’s common in regions like Canada, British Columbia, the northeastern United States, Washington, Oregon, northern Europe, and parts of China. In many regions, cherries coexist with snow during winter.
As an example, well-known varieties like Santina and Lapins originated in an experimental station in Summerland, British Columbia, Canada, where snow and cold are natural and normal conditions.
Naturally, cherries come from that side of the world, from a temperate and cold-temperate zone. However, in recent years, breeders have been developing varieties with fewer chilling hour requirements, primarily for commercial reasons and to cater to market demand. This allows cherries to be produced during months when there is no cherry production, both in the Northern and Southern Hemispheres. This trend is where we are heading.