Common Chilli Plant Problems
Most chilli problems are identifiable by their symptoms. Use this guide to narrow down what is wrong before treating.
Pests
Spider mite
Symptoms
Fine webbing under leaves; leaves develop a stippled, pale yellow mottling. Worst in hot, dry conditions.
Treatment
Increase humidity by misting regularly. Treat with neem oil spray or introduce predatory mites (Phytoseiulus persimilis) for biological control.
Aphids
Symptoms
Dense clusters of small green, black, or white insects on new growth and under leaves. Leaves may curl. Sticky honeydew residue.
Treatment
Blast off with water, then apply insecticidal soap spray. Repeat every 3–4 days. Ladybirds and lacewings are natural predators.
Whitefly
Symptoms
Clouds of tiny white insects fly up when the plant is disturbed. Leaves yellow and have sticky deposits.
Treatment
Yellow sticky traps catch adults. Apply insecticidal soap or neem oil, targeting the undersides of leaves where eggs and nymphs hide.
Thrips
Symptoms
Silver or bronze streaks on leaves; tiny dark frass specks. Flowers may be distorted or drop prematurely.
Treatment
Remove heavily affected leaves. Apply neem oil or insecticidal soap. Blue sticky traps target thrips specifically.
Pest control
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Diseases and deficiencies
Blossom end rot
Symptoms
Dark, sunken, leathery patch at the bottom of the fruit.
Treatment
Not a disease — calcium deficiency, often triggered by inconsistent watering. Fix watering, apply calcium foliar spray.
Mosaic virus
Symptoms
Mottled or mosaic pattern of light and dark green on leaves; distorted, crinkled new growth. Does not improve.
Treatment
No cure. Remove and bin the plant (do not compost) to prevent spread to other plants. Wash hands and tools after handling.
Powdery mildew
Symptoms
White powdery coating on leaf surfaces, usually starting on upper surfaces of older leaves.
Treatment
Improve airflow around the plant. Remove affected leaves. A dilute baking soda spray (1 tsp per litre) or potassium bicarbonate can help slow spread.
Root rot
Symptoms
Wilting despite moist compost; yellowing lower leaves; roots are brown and mushy rather than white and firm.
Treatment
Caused by overwatering or poor drainage. Allow to dry out. Remove from pot, trim affected roots, and repot into fresh, well-draining compost.
Environmental problems
Sunscorch
Symptoms
Bleached, pale, or white patches on leaves facing the sun — usually appearing after a sudden move from shade to full sun.
Treatment
Harden off gradually before placing in full sun. Affected leaves will not recover but new growth will be fine.
Cold damage
Symptoms
Drooping, dark or black patches, and wilting after cold nights. Chillies are sensitive below 10°C.
Treatment
Bring indoors before overnight temperatures drop below 10°C. Mild cold damage may recover with warmth; frost-damaged tissue will not.
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