Citrus Sudden Leaf Drop - Causes & Fixes

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Phytophthora Root Rot

This soil-borne oomycete attacks the root system of citrus trees, especially in poorly drained soils. As roots decay, the tree loses its ability to transport water and nutrients, triggering a stress response that results in sudden defoliation.

Very Common

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How to confirm: Check for dark, water-soaked lesions on the bark near the soil line and smell if the root area has a foul odor.

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1 Immediately prune away any mushy, blackened, or foul-smelling roots and repot the tree in a well-draining, sterile medium to prevent further spread.

Espoma Organic Potting Soil Mix

15.1 L

$22

In Stock

2 Improve soil aeration and drainage by incorporating horticultural perlite into the potting mix to prevent waterlogged conditions.

3 Apply a liquid seaweed fertilizer to help the tree recover from the extreme physiological stress and support new root development.

FoxFarm Bush Doctor Kelp Me Kelp You Liquid Seaweed Fertilizer 1 Quart

0.9 L • 1 pcs

$32

In Stock

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Extreme Water Stress (Drought or Flooding)

Citrus trees are highly sensitive to rapid changes in soil moisture. Sudden flooding can drown roots, while extreme drought forces the tree to drop leaves as a survival mechanism to reduce transpiration.

Very Common

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How to confirm: Probe the soil several inches deep to see if it is bone dry or saturated with standing water.

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1 Check the soil moisture level immediately using a probe to determine if the tree is suffering from drought or waterlogged roots.

GROWIT Soil Moisture Meter SMM-V3

Water Meters

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2 If the soil is bone dry, provide a deep, slow watering to reach the root zone; if the soil is saturated, ensure the plant is in a well-draining container or area to prevent root rot.

3 Apply a balanced fertilizer like FoxFarm Grow Big to help the tree recover and promote new vegetative growth once moisture levels are stabilized.

FoxFarm Grow Big Liquid Plant Food 1 Quart

0.9 L • 1 pcs

$30

In Stock

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Citrus Canker (Bacterial Infection)

While primarily known for lesions, severe bacterial outbreaks can cause systemic stress in citrus. This physiological strain can lead to premature leaf abscission as the tree attempts to shed infected tissue.

Common

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How to confirm: Examine the remaining leaves for raised, corky, yellowish lesions on both the upper and lower surfaces.

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1 Prune away all heavily infected or symptomatic branches using sterilized tools to prevent the bacteria from spreading to healthy tissue.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

$13

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2 Apply an organic fungicide/bactericide spray to the tree to help control the spread of the infection and protect new growth.

Bonide Captain Jack's Fruit Tree Spray 32 oz

0.9 L • 1 pcs • Organic

$36

In Stock

3 Ensure the tree is not under additional stress by maintaining consistent moisture and providing a balanced nutrient boost.

FoxFarm Happy Frog Citrus and Avocado Fertilizer

1 pcs • Organic

$21

In Stock

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Temperature Shock

Citrus trees are tropical/subtropical and highly susceptible to frost or sudden cold snaps. A sudden drop in temperature disrupts cellular function, causing the tree to shed leaves rapidly to protect its core.

Common

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How to confirm: Review recent local weather logs for temperatures that dropped below 32°F (0°C) or significant sudden shifts.

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1 Immediately move the citrus tree to a warmer, sheltered location or bring it indoors to a stable temperature above 50°F (10°C) to prevent further leaf loss.

2 Apply a liquid seaweed fertilizer to help the tree recover from environmental stress and boost nutrient uptake during this vulnerable period.

FoxFarm Bush Doctor Kelp Me Kelp You Liquid Seaweed Fertilizer 1 Quart

0.9 L • 1 pcs

$32

In Stock

3 Monitor soil moisture closely using a moisture meter to ensure the tree is not overwatered while it is in a stressed, non-transpiring state.