The tomato leaf curl is probably one of the most common problems that present themselves in tomato plants. Also known as the leaf roll, this condition can worry many new gardeners. If you're one, and you're noticing your tomato leaves curling down, here's the ultimate guide to help you out.
Get answers to the most pressing questions you might have about tomato plants, the common reasons why your tomato leaves are curling, and how to deal with it.
Is the Tomato Yellow Leaf Curl Worth Worrying About?
Leaf curl is a common problem in tomato plants, and a lot of other plants as well. The good part is, you don't need to be too concerned about it.
In most cases, leaf curls occur due to stress. While this stress isn't ideal for plants, it isn't too difficult to deal with too, and with the right measures, you should be on your way back to a healthy tomato plant.
There are, however, certain other causes that make cause the tomato leaves to curl.
Once you are able to diagnose the problem and take measures, you should be able to see better fruit production and new growth.
What Causes Curling Leaves on Tomato Plants?
There is actually a wide variety of reasons that might cause your tomato leaves to curl. Let's take a closer look at each of them.
Remember that the faster you take measures to correct the situation, the easier it will be to save your tomato plant.
Pruning tomato plants is actually a controversial subject. There are some gardeners who vouch for it, while some others vote against it.
Excessive pruning, however, is one factor that could cause the curling leaves. This is simply because when you prune your tomato plant more than necessary, you end up causing the plant to go under stress, which, in turn, leads to the leaf curl.
If you have been religiously pruning your plants, remember to exercise caution especially with tomatoes, and avoid taking off more than necessary.
If you spot the leaf curling after a pruning session, just leave the plant and avoid any unnecessary interaction with it during this vulnerable stage. The situation should resolve on its own in a few days.
Using the Wrong Fertilizer
Using a balanced fertilizer that has a good mix of nitrogen, potassium and phosphorous is important if you're dealing with a tomato plant for the first time.
However, it is important to note that nitrogen needs to be reduced at the fruiting stage of the plant- when it has achieved maturity. At this stage, a phosphorous and potassium fertilizer is to be used.
If you use too much nitrogen during this stage of plant growth, the leaves may curl.
Watering is exceptionally important for all plants, but even more so when it comes to tomato plants.
Because tomatoes have such a high water consumption, they can quickly get fussy if not watered correctly. or enough. In contrast, overwatering may also cause the plant to go under strain.
Underwatering a plant can affect its ability to function properly, while overwatering can cause damage to the plant's root systems.
Each of these stresses can cause plants to curl inward, and this is true especially for the tomato plant, which has very specific water requirements.
This is another one of the common causes that may lead to your tomato leaves curling up. Exposure to excessive heat, combined with the lack of water can cause the leaves to start curling in order to protect the plant from the sun, and prevent further water loss.
While tomatoes are sun loving plants, they find it difficult to adapt to very high summer temperatures. If temperatures stay over 85 degrees for a period of time, the tomato plants start to get under heat pressure.
When leaf curls appear in newly transplanted tomatoes, it is usually due to transplant shock. Tomato roots are usually very delicate, and if the plant is moved into a new area, they inevitably suffer a certain level of damage.
As the plant settles into its new position, it can display signs of transplant shock in the form of leaf wilting, yellowing, or even leaf curl. Fortunately mild transplant shocks can be avoided and the plant should recover by itself within a few weeks.
Tomato plants are actually very sensitive to herbicides. This is why, when they come in contact with commonly used herbicides like Dicamba and 2,4-D, they can start to develop certain problems.
It is important to note that the leaf curl that occurs when the plant is exposed to herbicides and weed killers is different than the leaf curl you'll observe due to other situations.
When the tomato plant undergoes stress or is underwatered, you'll notice the leaves curling inward. In contrast, when the plant is facing herbicide damage, you'll notice the leaves curling downward and even twisted around the stem.
If you are able to manage this kind of damage quickly, you might be able to save the plant. If the problem is severe, you might note stunted growth and other problems starting to prop up. In certain extreme cases, the entire plant may get affected.
Viral infection is another one of the common causes of the tomato leaves curling.
The tomato mosaic virus, which is usually spread through contaminated seeds, plants and equipment is another possible cause of the leaves curling up.
The tomato yellow leaf curl virus is transmitted via whiteflies. The infected plants usually take 3 weeks to show any symptoms, but once you do spot them, it is important to take immediate action to keep the viral infection from spreading to the other nightshades in your garden.
How to Deal With the Tomato Leaf Curl
Remember that when you notice the tomato leaves curling, it is actually your plant's way of communicating with you about something wrong. Once you have identified the environmental factors that are causing the leaf curling to happen, you can take steps to deal with it, and encourage new growth.
Control Herbicide Use
Exposure to herbicide drift or herbicide residue is one cause of the tomato leaves curling down that needs to be fixed.
If you spot some tomatoes that are affected, they must be discarded to reduce potential contamination from the crop.
Maintain Optimum Conditions
Considering how tomatoes need just the right amount of water and sunlight exposure to grow their best, try to maintain these optimum conditions as best you can. Focus on watering the plant just the right amount, and take measures to keep the plant from being exposed to a lot of heat.
Removing Residue Contamination
While a lot of herbicides persist for years within soil mulches and potting soil, you can take steps to remove the residue contamination and make the soil more friendly for tomatoes.
If you are concerned that the leaves are curling due to excessive nitrogen, just stop adding the fertilizer. The only possible outcome of this kind of overfertilization is that the plant may focus more on leaf production, and the leaves may end up more thick and leathery.
Other Ways to Keep the Tomato Leaves From Curling Down
To protect the tomato plants from stress due to excessive heat, you can install a shade cloth to cover the plant during the hotter parts of the day, and remove it during the earlier, less intense parts of the day.
If you are planting your tomatoes in pots, you can simply move them to a shadier spot.
Cleaning your garden gear frequently may help prevent infections like the tomato mosaic virus from spreading.
If you are concerned about how herbicide drift could be the cause of tomato leaf curling up, you can have a talk with the neighboring farms that you suspect are using the herbicide, and ask to be notified of the spray in advance, so that you get enough time to cover your plants and prevent any environmental stress or damage to them.
Why Are Tomato Leaves Curling Down and Turning Brown?
Tomato leaves tend to curl for various reasons, and while we've outlined pretty much everything here, there is still one aspect that you'll need to take note of if you have a tomato plant in your garden.
If you start notice the leaves rolling and drooping and find them changing their color from green to brown, it could possibly be due to root damage, in specific, root rot.
Root rot is basically what happens when the soil around your plant is saturated with water, and when there is excessive water around the root system.
Remember that the tomato plant has delicate roots, and overwatering (or underwatering) can lead to environmental stress which can, in turn, cause the plant leaves to get curly and even get brown in color.
Did this post help you out? Looking for some more help with planting, growing and harvesting tomatoes? Don't forget to check out this post!