Why does your Rhododendron hybridum hot have sudden leaf drop? Diagnose the cause and fix it with our step-by-step guide.
Rhododendrons have shallow, fibrous root systems that are highly sensitive to moisture fluctuations. Sudden leaf drop is a classic defense mechanism when roots are either suffocated by waterlogged soil or desiccated by extreme drought.
This soil-borne oomycete attacks the fine feeder roots of Rhododendrons, particularly in poorly draining soils. As the root system fails, the plant can no longer support foliage, leading to rapid leaf senescence and drop.
Rapid shifts in temperature, such as a sudden late spring frost or an intense heatwave, can cause physiological shock. Rhododendron hybrids often drop leaves to conserve moisture and energy when metabolic processes are disrupted by thermal stress.
While usually more gradual, severe deficiencies in acidic-loving plants like Rhododendrons can lead to weakened foliage and eventual drop. This is often exacerbated if the soil pH has drifted too high, preventing nutrient uptake.
Your plant might also be experiencing one of these issues:
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