The rising temperatures and climate change challenges of recent years have brought a significant threat to citrus trees. Heat stress, caused by prolonged exposure to high temperatures, poses a severe risk to citrus trees. Also, excessive soil evaporation, inconsistent rainfall, and poor soil water-holding capacity can make trees even more heat-sensitive.
How does heat stress affect citrus trees?
High temperature results in shorted internodes, heat injury especially on leaves, lower flower and fruit, fruit drop, and smaller fruits.
Heat stress symptoms on citrus tress
There are early signs of heat stress on citrus trees that help growers to lessen the heat damage. The signs include curled leaves, leaf and fruit drop, leaf bleaching and yellowing of canopy, growth slowdown, and fruit and leaf sunburn.
How to protect trees from the heat stress
Watering trees in the early morning to reduce transpiration loss helps trees tolerate the high temperatures of midday. Due to their immature root systems, newly planted trees should be watered more frequently during the summer. Citrus trees planted in sandy soils need more water compared to those planted in heavy soil.
Applying mulch at the tree’s base helps to retain soil moisture. This is particularly essential for young trees whose root systems are establishing near the soil’s surface. To prevent rotting, it is essential to allow a space between the tree’s trunk and the mulch.
More frequent watering enables trees to better absorb water and prevents drought stress. A sprinkler or drip system is an effective method for ensuring uniform irrigation. Watering during the hottest time of the day may result in rapid evaporation. Water early in the morning or in the evening.
Nutrient-deficient trees may be more vulnerable to the negative effects of high temperatures. Maintaining healthy trees requires a constant fertilization schedule that spans the entire year. Pruning should be avoided during periods of stress, as it may result in sun penetration into the interior of the branches and increase damage from heat. Application of pesticides during the hottest part of the day should be avoided, as the chemical can readily vaporize and cause leaf burning.
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