Why does your Rhododendron japonicum have sudden leaf drop? Diagnose the cause and fix it with our step-by-step guide.
Excessive soil moisture or poor drainage creates anaerobic conditions that promote Phytophthora species, which attack the sensitive root systems of Japanese Azaleas. This leads to a sudden inability to transport water, causing leaves to wilt and drop unexpectedly.
Rhododendron japonicum is sensitive to sudden temperature fluctuations, particularly late spring frosts or extreme heatwaves. Rapid changes cause the plant to enter a defensive state, shedding leaves to conserve moisture and energy.
Azaleas have shallow, fibrous root systems that are highly susceptible to drying out completely. When the substrate stays dry for too long, the plant will shed leaves as a way to reduce transpiration surface area.
Specific fungal pathogens can cause rapid defoliation when high humidity or wet foliage persists. While often characterized by spots, a severe outbreak can lead to premature leaf senescence and drop.
Your plant might also be experiencing one of these issues:
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