How to protect citrus and avocado trees before summer causes damage
Technical Recommendation for June
Anyone who works with citrus or avocado trees in the southern part of the country is familiar with the scenario: the first heat waves of May and June arrive, and with them comes an increase in physiological fruit drop, sunscald spots on the skin, and trees showing clear signs of stress. What isn’t always obvious is what’s happening inside the plant and why.
João Costa, researcher specialized in citrus and avocado trees, is the author of this June issue of the Recommendation by Hubel Verde, which focuses on strategies for mitigating heat and water stress in these crops.
“Under extreme temperatures and water deficit, the plant activates hormonal mechanisms associated with senescence and the physiological drop of fruits“, explains João Costa.
In practical terms: under extreme heat, the plant increases its production of ethylene and abscisic acid, hormones that signal stress and can cause premature fruit drop, damage to the fruit’s skin, and significant yield losses. This critical period coincides precisely with the post-flowering stage and the initial growth of the fruit, when the tree’s physiological demands are at their peak.
The window of opportunity for intervention is short. And it begins before symptoms appear.
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Water management: the first line of defense
Before any complementary strategy, irrigation remains the main factor in mitigating stress.
“In conditions of extreme heat, even small fluctuations in water balance can quickly lead to physiological stress”, emphasizes João Costa.
The irrigation schedule must meet the actual needs of the crop, without sharp fluctuations in the soil's water potential. Fertigation should occur during the cooler periods, as applying fertilizers in the middle of the day increases osmotic pressure in the rhizosphere and hinders water absorption precisely when the plant needs it the most.
In peaks of extreme heat, short bursts of comfort help reduce plant dehydration during the most critical hours, having a real impact on the physiological state of the tree.
Osmoregulation: helping the plant to retain water
When the plant experiences water stress, one of the main challenges is to maintain cellular turgor, that is, to keep the cells hydrated and functional.
Vegetal B60, based on betaine glycine, acts as an osmoregulatory agent, allowing cells to maintain water and functionality even under adverse external conditions.
“The goal is not only to reduce the impact of heat but to allow the plant to remain physiologically active", says João Costa.
The application should be preventive, in the days leading up to a heat wave, with a persistence of about 15 days. Applying after the symptoms appear is reacting too late.
Sunburn is not inevitable
Sunburn is one of the main causes of commercial devaluation in citrus and avocados, and it is also one of the most preventable.
The intense radiation causes photo-oxidative damage to the fruit's epidermis, compromising quality and visual appearance. Sugarplex Reflexo, formulated with zinc and sorbitol, addresses this problem systematically: zinc reduces oxidative damage caused by radiation; sorbitol facilitates the rapid transport of the nutrient to the fruit, via phloem, with high translocation efficiency.
Fruits without scalding maintain integrity, better post-harvest preservation, and higher market value.
Silicon: physical barrier against radiation and heat
Silprotect, based on high bioavailability orthosilicic acid, deposits silicon in the cuticle creating a barrier that filters infrared and ultraviolet radiation, reduces leaf temperature, and limits water loss through the leaf surface, a source of dehydration that often goes unnoticed.
“It also helps to improve stomatal function and preserve photosynthetic efficiency under extreme light conditions”, explains João Costa.
Protect what is already on the tree
In years of extreme heat, often the difference is not in producing more — it is in being able to protect what is already on the tree.
Vegetal B60 prepares the cell, Sugarplex Reflexo protects the fruit, Silprotect creates the physical barrier. Three complementary interventions that, applied at the right moment and based on well-calibrated irrigation, can make the difference between a compromised campaign and a harvest within expectations.
Anticipating critical periods and acting preventively is now an integral part of a serious technical strategy in citrus and avocado.
If you wish to adjust these strategies to the reality of your farm, the Hubel Verde team is available to assist in the field.
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