TheNaturePlanet

Don't panic if the leaves of your home-grown tomatoes curl or wilt! First, observe the symptoms, then check the environment, and you can "prescribe the right medicine" by identifying the cause.
1. Environmental Issues
1. Excessive Heat and Dry Soil
Symptoms: Leaves curl upward into a tube shape, turn dark green, and the plant looks wilted. This is most likely to occur in summer after 暴晒 (direct sunlight) or when a rainy day suddenly clears up.
Solutions:
Use a shade net to block the sun from 11 AM to 3 PM.
Avoid watering during the hottest hours. Use a spray bottle to mist the plant for cooling, watering small amounts multiple times to keep the soil slightly moist—do not let the soil alternate between dry and wet.
2. Cold Stress
Symptoms: Newly grown leaves curl and turn purple, while old leaves bend downward. Common during late spring cold snaps in early spring or temperature drops in autumn/winter.
Solutions:
Cover the soil with plastic mulch and build a small plastic tunnel for insulation. Keep the night temperature above 12°C.
Spray with 0.01% brassinosteroid lactone to help the tomatoes resist cold.
2. Nutritional Deficiencies
1. Improper Fertilization
Symptoms: Excessive nitrogen causes thick, dark green curled leaves; calcium or potassium deficiency leads to scorched and curled leaf margins, and may cause blossom end rot.
Solutions:
Stop applying nitrogen fertilizer temporarily. Spray with potassium dihydrogen phosphate or chelated calcium.
Add wood ash to the soil to supplement potassium, or spread gypsum powder to 补钙 (supply calcium).
2. Soil Salinity
Symptoms: White frost appears on the soil surface, and leaf margins become scorched and curled.
Solutions:
Flood the soil with water to leach out salts, then mix humic acid-based soil conditioners into the soil to improve its quality.
3. Pest and Disease Infestations
1. Viral Diseases
Symptoms: Yellowed, shriveled, and curled leaves, stunted plant growth. Transmitted by aphids and whiteflies.
Solutions:
Immediately pull out and discard infected plants. Spray with a solution of 2% Ningnanmycin water agent + 0.1% zinc sulfate.
Hang yellow sticky traps to catch pests, and use 10% imidacloprid to kill insects.
2. Root Diseases
Symptoms: Root rot or wilt causes roots to turn brown and rot, with wilting worsening after watering.
Solutions:
Drench the roots with a mixture of 3% metalaxyl·fludioxonil suspension seed coating agent + Bacillus subtilis.
Avoid continuous cropping of tomatoes in the same field; rotate with leguminous plants to reduce pathogens.
3. Mite Damage
Symptoms: Red spider mites or tea yellow mites leave white spots and webbing on the undersides of leaves, causing them to harden and curl.
Solutions:
Spray with 0.3% matrine water agent or 20% pyridaben, focusing on the undersides of leaves!
4. Poor Management
1. Excessive Pruning
Symptoms: Premature pinching or excessive leaf removal reduces photosynthesis, causing leaf curling.
Solutions:
Leave 6–8 leaves below each fruit cluster and spray with 0.1% seaweed acid foliar fertilizer to help the plant recover.
2. Excessive Pesticide or Hormone Use
Symptoms: Twisted leaves and swollen stems, mostly due to excessive concentration of regulators like 2,4-D.
Solutions:
Rinse the leaves with clear water immediately, then spray with 0.01% brassinosteroid lactone to promote recovery.
Daily Maintenance Tips
Root Care: Water with humic acid or seaweed acid water-soluble fertilizer every 10–15 days. Strong roots mean healthy tomatoes.
Fertilization: Alternate between balanced and high-potassium water-soluble fertilizers during the growing period; avoid overusing nitrogen.
Environment: Maintain a day-night temperature difference of about 10°C in greenhouses, keep air humidity at 60%–70%, and ensure good ventilation!