Vegetable Tomato Leaf Curl Virus: What Are The Causes & How To Fix Them?

Homegrown vegetables are a great source of nutrients and beyond-description delicious. These vegetable gardens bring beauty to the outdoor environments with great benefits for human health. Sometimes, human-grown vegetable gardens suffer microbial, environmental, and chemical problems that lead to a problem called tomato leaf curl.

Due to problems, all the leaves on the plants turn yellow, brown, and curled downward. The invasion of these insect pests and microbes reduces the quality and yield of vegetables. Initially, the damage by pests and microbes only appears on new growth while the older leaves remain intact. Therefore, damage to tomato plants and other vegetables might be due to problems and microbes or a combination of both.

It is essential to determine the real culprit that causes damage to tomato plants and other vegetables. This way, we’ll recover the tomato leaves and plants from injury.

tomato leaf curl problem
Healthy vegetable garden with cucumber and tomatoes

What Factors Are Responsible For Tomato Leaf Curling?

Like other homegrown vegetables, tomato plant leaves start curling and rolling downward. Tomato leaf curling is a sign of viral infestations, environmental and physiological factors.

The following is a  breakdown of all the factors one by one that is responsible for tomato leaf curl:

1. Viral Infections Cause Tomato Leaves Curling

One of the significant factors contributing to tomato leaf curl is viral infections. There are hundreds of these viruses that infect tomato plants. And the infected plant shows the symptoms of pale green leaves that tend to curl upward.

Viral infection causes tomato leaf curling
Symptoms of tomato leaf curl virus, the infected plant leaves are pale green and curled upward (especially the new growth).

In addition, the diseased plants indicate stunted growth with little to no fruit production. And the leaves of infected plants are yellow (due to chlorophyll breakdown), malformed, and purplish, along with thickened veins on the underside. When infected with the tomato yellow leaf curl virus, these symptoms appear on tomato plants.

The whiteflies on the underside of a plant leaf with thick veins and these tiny plant enemies are responsible for the transmission of tomato viruses.

More interestingly, the whiteflies transmit this virus in tomato plants during their long hours of feeding.

Tomato leaves curling
Severely damaged tomato plants
tomato leaf curling virus infected
Tomato mosaic virus-infected tomato plants with mottled coloring

Another virus that stunts tomato plant growth is the tomato mosaic virus. It causes the tomato plant leaf to roll and curl. In addition, the foliage of infected tomato plants exhibits mottling and deform growth. While the tomato fruit production turns brown inside, thus impacting the fruit quality and consumption.

Virus infected
Tomato mosaic virus-infected fruits (poor quality and not consumption) lead to economic damage.

RELATED: What Is Eating Holes in Your Tomatoes? | Causes and Solutions

2. Leaf Roll Or Physiological Leaf Roll

The second most crucial factor for tomato leaf curl is physiological leaf curl or roll. It is primarily due to excessive moisture, drought, high temperatures, root damage, insufficient nutrients (mainly nitrogen and phosphorous), transplant shock, and repeated pruning.

tomato leaves near the ground
The tomato leaves near the ground exhibit the leaf rolling (physiological leaf curl)
Tomato leaf rolling
Close up of tomato leaf rolling

Initially, the physiological leaf roll symptoms appear near the ground. Then, the tomato leaves and leaflets start upward, cupping and rolling. And the tomato leaves become hard, thick, brittle, and appear leathery.

The tomato leaves roll completely inwards toward the central midrib as the physiological injury worsens. But, the infected leaves remain green and gradually dries and fall down to the ground.

Like viral infections, the physiological leaf roll conditions may occur at any time of the tomato growing season. And sometimes, it may not initiate reproductive growth.

3. Herbicide Injury

Herbicide drift or injury also causes tomato leaves to curl and roll. Tomato plants are susceptible to broad-spectrum chemicals such as 2,4-D herbicides. These herbicides instantly kill tomato seedlings and plant growth. Even the herbicide-exposed tomato plants show leaf curling, low rolling, and stunted growth.

Herbicide injury
Tomato seedlings injury because of herbicide exposure

Due to herbicide drift, tomato plants cannot reproduce and produce fruit. In-home gardens, weed kills such as glyphosate and Ortho Weed-B-Gon, and Freezone kills unnecessary herbs. And tomato plants are susceptible to these chemicals, even at low rates.

If the new growth on tomato plants shows no sign of injuries, there are still four to six weeks in the growing season. Then, however, it means the tomato plants are recovering from injury and can overcome herbicide adrift.

Badly injured tomato plant
Badly injured tomato plants

On the other hand, if the new growths on tomato plants show leaf curling and twisting, it means the plant has succumbed to injuries and cannot recover. The only solution is the pulling out of tomato plants.

4. Broad Mite Damage

The tomato leaves are curling because of viral infections, herbicide drift, and plant physiology abnormalities. In addition to all these factors, there is also broad mite damage that causes tomato leaves to curl.

Broad mite damage
Broad mite damage on tomato leaves

Broad mites are sensitive to light; therefore, they prefer to feed on the underside of leaves and inject toxins into plants. Due to injected toxins, the tomato leaves start rolling, curling, and twisting. And the symptoms of broad mite damage resemble the yellow leaf curl virus.

Broad mite - tomato leaf curling
Broad mite on tomato leaf (in the center with shiny transparent appearance)

The infestations of broad mites on tomato plants depend on food sources, light intensities, and weather. Broad mites infestations may be due to tomato transplants from greenhouses and whiteflies (broad mites attached to antennas of sap-sucking insects). If a tomato plant is badly infested, instantly pull off the entire plant and dispose of them. 

Tomato Leaf Curl: How To Fix It?

Viral infection, heat stress, herbicide damage, severe pruning, and environmental stress lead to tomato leaves curling and decreased fruit production.

The factors mentioned above cause damage to tomato plants, such as curling leaves, root rot, less fruit yield. Also, the leaves tend to roll upward with little to no product.

The following list sheds light on multiple methods and practices to fix it to prevent tomato leaf curling and damage from these various factors.

Prevention From Physiological Leaf Roll

Due to physiological alterations, the tomato leaves curling is not as severe as the viral infections and herbicide drift. The best thing is physiological leaf roll damage in tomato plants can easily be cured through proper cultural practices. This condition also has minimal impact on tomato fruit yield.

Here these are the list of cultural practices that can lessen the chances of physiological leaf roll:

  1. Do not allow or place the poorly established plant near the healthy ones. The best solution is to remove the plant and discard it.
  2. The vine tomato (indeterminate varieties) plants are more susceptible to physiological leaf roll and damage. Therefore, only select bush tomatoes to prevent physiological leaf roll for home gardens.
  3. Maintain the cleanliness in the garden. Feed the tomato plants with sufficient nutrients (not too much nitrogen and phosphorus).
  4. Do not overexpose the tomatoes to the sun; otherwise, drought and heat stress will cause.
  5. Maintain a consistent moisture level for tomatoes to avoid leaf curl
  6. Avoid severe pruning of plants and root damage by tilling
  7. Use organic mulches to prevent the moisture loss
  8. Do not apply contaminated compost in the vegetable tomato garden

Prevention From Viral Infection

There is no recommended chemical treatment for viral infections in home gardens because it will harm the beneficial insects, birds, and other plants. However, to prevent plants from viral infestations following are the best recommendations:

  1. Plant disease-resistant varieties and properly maintain them
  2. Pruning of infected or diseased tomato plants is recommended
  3. Removal and discard of badly infected plants are helpful in the prevention of leaf curl and roll
  4. Removal of weeds from the garden will prevent the damage of tomato leaf curl virus
  5. And the best solution is to prevent the viral-induced leaf curl by controlling whiteflies because they transmit hundreds of viruses.

RELATED: To The Rescue: How to Save Tomato Seeds

Prevention From Broad Mite And Herbicide Damage

To minimize the herbicide damage and broad mites, the following are the best techniques:

Control Broad Mites

  1. Briefly spray the plants with sulfur-based miticides
  2. Spray plants with insecticidal soap and horticultural oils for rapid control of broad mites
  3. Establish predatory mites before the establishment of broad mites. These are commercially available as Benemites, Arbico Organic, and Grow Organic
  4. Pull off the severely damaged plants and discard them

Prevent Herbicide Damage

  1. Always read the product labels carefully before application
  2. Do not spray the herbicides near growing plants or plants with new growth
  3. Always use the hooded sprayer to prevent the injury of neighboring plants
  4. Avoid spraying when the wind is blowing
  5. Use correct spray nozzles
  6. Do not spray when the wind speed is 5 mph because it will blow the droplets towards sensitive garden plants.

Frequently Asked Questions (FAQs)

How Do You Prevent Tomato Yellow Leaf Curl Virus (TYLCV)?

The best solution to prevent tomato yellow leaf curl virus infestations is to use resistant plant varieties. Prevent the plants from whitefly infestations because they are the primary source of this virus transmission. Pru prunes the infected plants and discards them.

Why Are My Leaves Twisting?

The leaves of your plant are twisting because they might be infected with viruses and infested with broad mites. In addition, the general mite infestations cause leaf curling because they inject toxins into the foliage while feeding.

To prevent leaf damage from broad mites, spray plants with insecticidal soap, neem oil, and horticultural oils. Also, apply predatory mites for the control of broad mites.

Now that you know how to prevent tomato leaf curl, make sure to read our other tomato plant care tips:

To The Rescue: How to Save Tomato Seeds

All Caged Up: How to Use a Tomato Cage

Tomato, Toh-Ma-Toe: The Ultimate Guide to Tomato Trees