Prevent and treat tomato leaf curling issues effectively

Learn to address tomato leaf curling with prevention and treatment tips.

The leaves on tomato plants can become twisted or curled due to environmental, chemical, or biological factors. Sometimes, we observe all leaves on the plant curling or rolling up, while the older ones remain unaffected.

Tomato leaf curling

Initially, leaf curling may seem mild, but it can progress rapidly. There are five primary reasons for leaf curling:

• Due to the use of herbicides and high residue levels.
• Due to viral infection.
• Due to strong winds from a storm.

Due to herbicide use:

If tomato plants are treated with herbicides to prevent or eliminate weeds, it can potentially harm the tomato plants. Tomatoes are highly sensitive to herbicides, which can lead to nutrient deficiencies, impacting both yield and disease resistance.

Leaf curling due to viral infection:

Commonly found in tropical and subtropical regions, this virus poses a continuous threat to gardeners. Plants affected by leaf curling virus cannot recover and may either die or remain stunted, failing to produce fruit.

Due to stormy winds:

Strong winds and low humidity can damage tomato leaves and stems. Low temperatures and humidity can cause the edges of tomato leaves to die, curl, and roll up. Hot and dry weather can also induce a phenomenon known as physiological leaf curl. This is a protective response where the plant curls its leaves slightly to conserve water. Mild leaf curling typically doesn’t reduce yield or quality, but severe symptoms may lead to flower drop and reduced fruit set. This issue is not a cause for concern as the plant typically returns to normal when weather conditions improve.

Tomato leaf curling due to a virus

Causal Agent

The disease-causing virus responsible for tomato leaf curling belongs to the Begomovirus genus, Germinivirus family, causing significant crop damage worldwide. Approximately 40 species of begomoviruses are known to cause tomato yellow leaf curl disease.

Symptoms

This is one of the most common and severe viral diseases affecting tomato plants globally.

Symptoms of the disease are most pronounced on young leaves at the top of the plant.

Affected leaves become distorted, narrow, and yellow from the margins towards the midrib (especially in young leaves). The leaves curl upward, resembling a spoon. In the early stages of infection, the growing tips of the plant will quickly curl and fail to develop, leading to no fruit production.

The majority of commonly grown tomato varieties in production are susceptible to yellow leaf curl.

Transmission and Development Conditions

Tomato begomoviruses are not transmitted through seeds or mechanical contact. The virus enters the plant and fields through the silverleaf whitefly (Bemisia tabaci).

Preventive Measures

To prevent yellow leaf curl disease in tomato plants, a combination of integrated measures is essential, including:

1. Use disease-resistant tomato varieties.
2. Eliminate disease sources in the field (weed removal and destruction of infected plants).
3. Maintain good hygiene for hands, feet, and tools (pruners, shears) before and after each pruning session.
4. Control insect vectors like whiteflies.
5. Protect young plants in nurseries (grow them in isolated structures such as greenhouses or net houses).
6. Apply balanced fertilization with all necessary nutrients.