Leaf damage on woody plants
Abnormal, damaged or falling leaves on a prized climber, shrub or tree can be alarming; however by following these simple steps to pinpoint the cause, gardeners can take effective action to protect their plants.
Plants affected: All climbers, shrubs and trees
Main causes: Adverse environmental factors
Timing: All year
Leaves can suffer a number of different forms of damage:
- Abrasions and superficial tissue damage
- Discoloured leaves
- Corky areas of leaves
- Creased leaves
- Curled leaves
- Deformed leaves
- Shedding of leaves
- Shredded leaves
- Sticky leaves
- Stunted leaves
Symptom, cause and control
This can be caused by children, wildlife and especially above all, by the wind.
Control: Provide protection from wind and other sources of mechanical damage or choose plants that are less affected.
Yellow leaves often indicate lack of nutrients or poor root function, perhaps due to root disease, waterlogging, soil compaction or drought. Alkaline soils can have the same effect on ericaceous plants such as rhododendrons.
Control: Improve growing conditions by remedying poor drainage, watering and using fertilisers, including foliar feeds that might get nutrients into plants despite root function being impaired. Avoid planting ericaceous plant on alkaline soils.
Brown or blackened leaves
The reasons vary and are covered in advice on brown leaves on woody plants. Corky areas of leaves could be mean the plant is suffering from oedema.
Control: See our advice in odema for further information.
Creased and curled leaves
Creased leaves indicate uneven growth caused by weather damage. Curled leaves can be due to drought, cold damage, excess sunlight, sap-sucking insects or caterpillars that bind leaves.
Control: See our advice in weather damage for further information on protecting plants from weather. Provide protection from stress and control insect pests to prevent curling.
These could be caused by frost damage to young foliage that then develops distorted foliage as it grows. Alternatively, weedkiller may have been to blame.
Control: Provide protection from stress and avoid weedkiller contamination of plants or their rooting zones.
Small irregular holes can be due to poor growing conditions in deciduous trees, but are usually caused by insects feeding on the foliage.
Control: Improve growing conditions and control insect pests of foliage.
Shedding of leaves
Some leaves are lost naturally; evergreen leaves for example are long-lived, but are replaced every few years. This often occurs in summer and can be alarming. However natural replacement is usually confined to lower leaves and those within the mass of foliage or canopy. Other causes are overwatering, waterlogging, drought stress and leaf disease.
Control: Remedy over-watering, waterlogging, drought stress and control leaf diseases.
Certain diseases and also environmental stress can cause numerous small holes in foliage, for example, fungal leaf spots and bacterial canker.
Control: Improve growing conditions and control fungal leaf spots and bacterial canker if applicable.
Wind and hail damage are the usual causes, but insect grazing might be mistaken for this.
Control: Provide protection from wind and other sources of mechanical damage; control insect pests if appropriate.
Sticky leaves are often caused by honeydew from sap-sucking insects such as aphids, mealybugs or scale insects feeding on leaves and shoots above the sticky area.
Control: Control any aphids, mealybugs or scale insects that may be feeding on leaves and shoots above the sticky area.
Poor growing conditions such as lack of nutrients could be a cause of stunting as could impaired root function due to waterlogging, low temperatures and also weedkiller damage.
Control: Avoid this problem by improving the soil conditions, especially avoiding waterlogging. Provide protection is possible in periods of low temperatures. See our advice in waterlogging and flooding for further information.
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