Why does your Rhododendron racemosum have sudden leaf drop? Diagnose the cause and fix it with our step-by-step guide.
As a moisture-loving species, R. racemosum is highly susceptible to Phytophthora if soil remains waterlogged. This pathogen destroys the root system's ability to transport water, triggering an emergency physiological response where the tree sheds leaves to conserve resources.
Despite their preference for moisture, sudden extreme dry spells can cause R. racemosum to enter a state of dormancy-like stress. The tree drops leaves rapidly to reduce transpiration surface area and prevent total dehydration.
Rapid swings from warm days to freezing nights can damage the tender leaf tissue of this species. The sudden cellular rupture in the leaves causes them to lose attachment to the petioles and fall.
A sudden lack of available nitrogen, often caused by leaching in heavy rains, can lead to chlorosis followed by leaf senescence. While usually a slower process, severe deficiency can cause premature shedding in woody rhododendrons.
Your plant might also be experiencing one of these issues:
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