(This publication was previously published on Smartcherry by Sofía Cáceres, our Technical Manager)
Frosts represent a silent threat capable of destroying in minutes what took months to develop. In cherry orchards, these extreme weather events cause catastrophic losses ranging from 26.7% to 99.3% of production, depending on the species and environmental conditions.
The 2024 season left a deep mark on Chile's central production areas. Temperatures dropped to -3°C in regions like Valparaíso, O'Higgins, and Maule, causing significant losses in orchards without protection systems. The economic impact resonated with every affected producer, transforming harvest hopes into million-dollar losses.
When ice attacks cells
Frost damage begins at the microscopic level. Ice crystals form within plant tissue following two lethal paths. Intracellular frost generates crystals directly in the cell protoplasm. Extracellular frost forms ice between cells, creating an osmotic deficit that dehydrates and collapses vital structures.
The rate of cooling marks the difference between cellular life and death.
When cooling occurs rapidly, the damage becomes irreversible. Ice simultaneously invades intercellular spaces and the interior of cells, preventing any adaptation. Cell membranes break down. The protoplasm disintegrates. Affected tissues acquire that characteristic dark color announcing death.
Critical thresholds are clearly defined. At -2.22°C, 10% of the buds are lost. At -4.44°C, the devastation reaches 90%. Each degree below the freezing point exponentially multiplies the damage.
Vulnerability according to phenological stage
The susceptibility of the cherry tree varies dramatically depending on its developmental stage. Between swollen bud and exposed cluster, vulnerability reaches its peak. It is as if nature specially punishes this spring awakening.
Studies from the Southwest Michigan Research and Extension Center revealed alarming patterns. Crops in the tight cluster stage suffered damage from 51.9% to 76.9%. Those in the green tip stage showed losses from 50% to 62.6%.
Duration intensifies the impact.
Prolonged frosts cause greater destruction than brief temperature drops. During winter, these episodes can extend for hours, especially at dawn. Each additional minute of cold exposure reduces recovery chances.
Lost flowers, ruined harvests
Within each cherry blossom, the pistil emerges as the most vulnerable structure to cold. This female reproductive organ succumbs first, followed by the stamens and finally the petals. The death of the pistil irrevocably seals that flower's fate.
The diagnosis is simple but evident. By cutting a swollen bud, a black pistil reveals death. A green pistil promises life. For cherry trees, every flower counts. Unlike apples or pears that can lose 50% of their flowers without seriously compromising the harvest, cherries require multiple individual fruits to achieve commercial yields.
When the damage persists until harvest
Frosts leave invisible scars that manifest months later. Trees stressed by cold produce fruits with compromised cellular integrity, reduced firmness, and shorter shelf life. Sugar accumulation patterns are altered. Acidity profiles become unbalanced.
Bound calcium decreases significantly in fruits from frost-affected trees. This critical indicator predicts future problems: increased vulnerability to pitting, accelerated pedicel dehydration, heightened susceptibility to fungal infections during storage.
The commercial implications are dire.
Export markets, especially China, demand superior quality standards. Fruits from stressed trees rarely meet these demands, forcing their sale in local markets at significantly lower prices.
Mass abortion: protecting the tree's offspring is essential
Fruit abortion represents a complex physiological response to frost stress. During the first 25 days after full bloom, any fruit that surpasses this period has successfully completed initial setting.
Frosts disrupt this delicate balance. Damaged tissues require additional energy for repair, creating competition for limited carbohydrates. In its evolutionary wisdom, the tree sacrifices fruits to ensure its own survival.
Death of young trees and long-term losses
Young cherry trees, especially those between 1 and 5 years old, face particular risks. Winter damage in these trees follows characteristic patterns, primarily affecting the xylem instead of the typically damaged phloem.
Damaged wood acquires a distinctive light brown color. Damage lines precisely match the depth of snow during the cold event. It is an accurate photograph of disaster, recorded in the tree's anatomy.
The mechanism is treacherous. Warm winter periods raise trunk temperature, especially when snow reflects sunlight onto the bark. Subsequent sudden cold finds the tree unprepared, unable to reacclimate. Death can be total.
The new challenges of climate change
Climate change is redefining the risk map for cherry production. The transition from El Niño to La Niña in 2024 brought lower precipitation and cold episodes during the critical budding period.
The paradox feels strange.
While average temperatures rise, climatic volatility intensifies the risk of devastating frosts. Warm periods accelerate bud development, increasing their vulnerability when the inevitable cold waves arrive.
Producers face an unpredictable enemy. Traditional strategies based on historical data lose effectiveness in the face of increasingly erratic climatic patterns. Thus, the industry recognizes the urgent need for more robust and adaptable protection systems.
Frosts will continue to be a structural threat to cherry production. Every spring brings with it the anxiety of clear nights and descending thermometers. The battle between cold and life repeats, leaving winners and losers in a game where the stakes are high and the rules constantly change.
