What causes the tops of tomato plants to curl?

Curling tomato leaves are surely not to be overlooked. Loads of lush foliage help your plant produce all the deliciously ripe tomatoes you’ve been patiently growing. Nevertheless, if you see curled leaves on your tomato plants, your crop may be jeopardized. Curled up leaves indicate that something is wrong in the surroundings or inside the plant itself. Then, examine your tomato leaves closely to see why they are curling. Common culprits include not enough moisture, nearby herbicide use, and diseases. These are the top five causes of tomato leaf curl and what you can do about them.


1. Tough Growing Conditions

Nature may provide a number of difficulties to tomato plants as they develop. According to experts, the most prevalent reason of tomato leaf curl is poor growth circumstances, which is also the simplest to correct. “Leaf curl is primarily driven by hot weather, lack of moisture, and heat stress, ” says Dr. Ajay Nair, Extension Vegetable Specialist at Iowa State University. The leaf edges roll upwards under very hot and dry circumstances. Nair claims that curling is more common on the lower leaves.

The science underlying this stress-induced leaf curl indicates that it is a protective mechanism used by plants. When hot, dry conditions persist, tomato plants are not able to take up as much water as they lose through evaporation. Leaflets curl up as a result of the internal water deficiency. A curled leaf absorbs less sunlight and loses less water. Leaf curling is a self-defense technique.

What to do: Lowering the environmental stress that causes leaf curl may both assist and avoid the condition. Begin with proper watering techniques. Aim for 1 inch of water each week for tomato plants. If plants do not get that amount from rainfall, supplement using a hose or drip line that delivers water directly to the root zone. To minimize disease transmission, avoid overhead watering. To reduce soil moisture evaporation, add a 2-inch layer of mulch around tomato plants.

Leaf curl caused by difficult growth circumstances normally disappears as conditions improve. Expect no long-term repercussions. A short battle with leaf curl “does not significantly reduce plant growth or yield,” says Nair.

2. Too Much Pruning

Although trimming tomato plants might assist stimulate fruit growth, removing too much foliage at once can create difficulties. The plant senses the sudden loss of energy-generating leaves and then curls its remaining leaves as a stress response.

What to do: Excessive pruning is best treated by thoroughly watering the plant and allowing it to recover. Let new leaves to grow. After a few weeks, the plant should be back to normal.

3. Transplant Shock

Putting seedlings or young starts into your garden might cause tomato plants to become stressed. Temperature fluctuations and root disturbance associated with transplanting cause some tomato varieties to curl up their leaves in self-defense.

What to do: After a few of weeks, plants frequently recover on their own from leaf curl induced by transplant shock. Once your tomatoes settle in, provide lots of water. To minimize transplant shock in the future, make sure to slowly acclimate seedlings to garden conditions before planting, and gently handle the root ball. Do your transplanting on a cooler, overcast day or give your newly transplanted tomatoes some temporary shade with a tarp or other material that will block direct sunlight.

4. Weed Killers

Your tomato leaves may be curled due to a weed-free lawn. “Off-target drift of herbicides like 2,4-D or dicamba is a common culprit,” Nair explains. If wind blows weed killer onto your tomato plants, the chemicals will affect foliage growth and may even kill your tomatoes. Herbicide-damaged plants have leaves that bend downward and individual leaflets that bend upward in a cup-like form. This differs from the tightly coiled or rolled leaves that result from hot, dry growth circumstances.

Herbicide-related leaf curl may also be caused by contaminated compost or mulch. Nair says the contamination comes from long-lived pasture herbicides such as picloram, clopyralid, or aminopyralid within the commercially available compost materials. As compost is dispersed around the garden, it might have an effect on tomatoes.

What to do: Herbicide-induced leaf curl is incurable. Have a “wait and see” attitude. Some plants will be able to withstand the damage and produce a yield. Some plants will perish if they do not bear fruit. Avoid applying weed killers near tomato plants in the future. Know where you get your compost and mulch, and make sure you buy from a reliable vendor.

5. Tomato Diseases

While uncommon, several viral tomato illnesses may be the cause of curling leaves. If a virus is to blame, you’ll see twisting and twining new growth, as opposed to curled older leaves common for plants stressed by tough growing conditions. Each new leaflets are prone to curling.

What to do: Tomato viruses are incurable. To assist prevent spread, remove the whole plant from the garden. Choose newer kinds with viral disease resistance in the future.

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