Tomato Yellow Leaf Curl: Causes and Cures

Updated on May 6, 2019
lobobrandon profile image

From his early days, Brandon helped his grandmother in her garden. He has always been passionate about tomatoes.

Tomato plants respond to stresses and diseases in different ways. One of the most prominent being the curling or rolling up of their leaves. If you notice that the new leaves or maybe all the leaves of your tomato plant are curling up it is recommended that you investigate your plant and its surroundings to determine the cause of the problem. You should do this quickly because these problems are mainly caused by factors that eventually affect the flowering and fruiting of the plants.

Common Causes of Tomato Leaf Curl

Some of the common causes of tomato leaf curl are listed below, and an explanation of each follows:

  1. External stress
  2. Non-Parasitic leaf roll
  3. Herbicides
  4. Tomato yellow leaf curl virus
  5. Broad mites

One easy way to prevent this problem is by planting tomato species that are meant to grow in your climatic conditions and also by selecting disease-resistant varieties. But if you've encountered this problem, all hope is not lost, curling in most cases can be cured and the tomato plants could recover and bear fruit.

Note:

Some varieties of tomatoes always curl their lower leaves while new leaves are uncurled. To find out if your variety does this, you're going to have to speak to an experienced gardener or look it up on the internet.

External Stress

Leaf curl that is caused by some external stress factors is more likely to be found in potted plants and plants in grow bags when compared to plants in a garden. Leaf roll is found on tomato plants in wet and cool conditions. Inconsistent watering and pruning are also factors that could lead to curling.

If it's just the lower leaves that begin curling upwards on the edges, forming a cup, one possibility is that the soil is too soggy. It is therefore important that you allow the top of the soil to be dried out a little before you water again. For plants in pots with drainage, water freely but do not allow water to be stagnant in the collecting tray at the base, because this can lead to root rot. Following the best practices when watering tomatoes helps prevent a lot of problems, you'd definitely want to take note.

Note: When the curling of the leaves is caused by external stress factors, the plants often continue growing and outgrow the condition, allowing them to flower and fruit well.

Non-Parasitic Leaf Roll

Non-Parasitic leaf roll is a kind of physiological leaf roll where the leaf tends to roll inward. In extreme cases, the leaves roll to an extent where they begin to overlap making it look like a serious issue. It is usually caused by irregular irrigation and bad pruning. The plant usually recovers from this shock very quickly and you don't have to worry about it provided you begin watering deep and consistent and follow good pruning techniques.

You know your plant suffers from this kind of leaf curl when the problem begins with the leaves folding upwards, kind of forming a cup, to go on curling even more such that the new leaves seem to be overlapping each other. Also, you would notice this issue on all the leaves of the plant.

The good news though is that the plant growth is not really stunted or hindered by this condition and you're not going to see any effects on the fruit. This issue is rectified after following correct watering techniques (deep regular watering) or a few days after pruning when the plant has recovered from the shock. Pruning is good when done right, the word shock should not make it seem like something bad has happened to the plant, it's just a reaction.

Herbicides

In almost all cases of leaf roll due to herbicides, it is not the gardener but an immediate neighbor or the neighborhood where someone uses herbicides which are carried over by the wind.

The culprit is almost always a lawn herbicide and it is usually Phenoxy types like 2, 4-D. The tomato plant is susceptible during all stages of growth.

A sign that it may be caused by herbicides is when the leaves curl downwards and pucker. In extreme cases, the stems become stiff and have a whitish layer formed on them. The tips of new leaves will be elongated and leaf veins turn lighter and seem to be parallel when compared to older unaffected leaves.

If your plant is already fruiting during this stage, the fruit turns out to be pointy and is usually harder to take off from the plant and you may have to chop it off and not just twist and remove.

You can prevent this by not using lawn clippings that come from lawns that were treated with herbicides. The other thing you could do for mild cases is water the foliage of the plant so as to wash off the herbicide. Make sure you do not water when the sun is up.

Tomato Yellow Leaf Curl Virus

Not a very innovative name, the tomato yellow leaf curl virus (TYLCV) was identified in 2007 and there was an extensive program put out to educate farmers as its occurrence was common in greenhouses and not open gardens. This does not imply that it does not occur in open gardens, it does. The virus is spread by Whiteflies which feed on tomato plants. If you've heard of this virus spreading in your region it would be best to not plant tomatoes close to other crops that Whiteflies love, such as peppers.

The affected plants suffer from stunted growth and the edges of the leaves curl upwards, with the leaves themselves being yellowish and deformed. Plants that are affected by this virus are best removed and burned because they do not fruit as blossoms drop. The early signs are different though. The first leaves soon after an infection cup downward. If your plant is affected after the fruit has already formed, the fruit will continue to grow and will ripen too.

Tomato Yellow Leaf Curl Virus
Tomato Yellow Leaf Curl Virus | Source

Tobacco Mosaic Virus

A more common occurrence is the Tobacco Mosaic Virus (TMV) which causes the leaves to be deformed with light and dark green mosaic patterns on the leaves with the leaves curling upwards if they curl. They do not always curl with the TMV. If your plant is infected you will notice a stunted growth and the blooms may have brown streaks.

There is no real cure and the virus is capable of living outside its host for a while and is mildly resistant to heat. Unlike the TYLCV that is spread through Whiteflies, the TMV is spread through contact. If you, therefore, notice that a plant has this problem, uproot it and any in the vicinity and bury deep or burn the plant.

Notice how the Tobacco Mosaic Virus causes the leaf to have patches of green mosaic that is yellowish but not yellow. The leaf also curls upwards.
Notice how the Tobacco Mosaic Virus causes the leaf to have patches of green mosaic that is yellowish but not yellow. The leaf also curls upwards. | Source

Broad Mites

Broad mites are sensitive to light and are usually present on the underside of tomato leaves and flowers. While they feed they inject toxins into the plant which distort the leaves.

You would not really notice a problem if broad mites are feeding on your plants unless the infestation is severe. In such cases, if you notice a distortion of young leaves and flowers look underneath for bronzed marks. You will not be able to spot the broad mites with your naked eye as they are really small at around 0.15 - 0.30 millimeters. If you do spot them using a microscope, they will be oval shaped and be either yellow or yellow with a tinge of brown.

Broad mites are either transported on the backs of Whiteflies or you can get them through transplants you buy from a local greenhouse. In case of severe infection, you may have to pull out your plants or alternatively consult an expert to confirm that it is, in fact, broad mites and begin using some sulfur-based miticides. It is best to consult an expert because you're also going to need to know whether your tomato variety is capable of withstanding the miticide you use. If you want to know more about broad mites in general, check this out.

This is what broad mite damage looks like. The picture is of a pepper plant, but it's exactly the same as a tomato plant. Notice how only the new leaves are attacked.
This is what broad mite damage looks like. The picture is of a pepper plant, but it's exactly the same as a tomato plant. Notice how only the new leaves are attacked. | Source

Other Causes for Yellowing of the Leaves

It is also a possibility that your tomato plant just has yellow leaves and not a yellow leaf curl. There are plenty of reasons for this to happen and I have covered the major causes in my article on yellow tomato leaves.

This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.

Comments

    0 of 8192 characters used
    Post Comment

    No comments yet.

    working

    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://dengarden.com/privacy-policy#gdpr

    Show Details
    Necessary
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Features
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Marketing
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Statistics
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)