Tomato yellow leaf curl is a virus disease that turns a vigorous tomato plant into a small, stunted, unproductive one, and it does so quickly. The leaves curl upward, turn yellow between the veins, and stay small; the plant stops growing, flowers drop, and the fruit that does set is small and ripens poorly. A plant infected young may never grow more than a foot tall, and it will produce almost nothing. The disease is a major problem in warm climates, where the whiteflies that carry it are active for most of the year, and it is spreading into new areas as the climate warms.
The virus is tomato yellow leaf curl virus, and it is carried from plant to plant by whiteflies — specifically the silverleaf whitefly — which pick it up when they feed on an infected plant and pass it on when they feed on a healthy one. The virus lives inside the plant's cells, so no spray can cure it, and an infected plant stays infected for life. The control is about keeping whiteflies off the plants, growing resistant varieties, and removing infected plants promptly, because every infected plant is a source of virus for the whiteflies to carry to the rest of the garden.
What tomato yellow leaf curl looks like: symptoms
- Upward leaf curling: the leaflets curl upward and inward, giving the leaves a cupped, rolled appearance that is the most distinctive sign.
- Yellowing between the veins: the tissue between the veins turns yellow while the veins stay green, producing a yellow mosaic pattern on the small, curled leaves.
- Tiny, stunted leaves: new leaves are much smaller than normal, and they stay small, so the plant looks dwarfed from the top down.
- Severe stunting: a plant infected young may grow to only a fraction of its normal size, with short stems and a bushy, stunted habit.
- Flower drop and poor fruit set: flowers drop without setting fruit, and the fruit that does set is small, uneven, and slow to ripen.
- A plant that stops growing: the plant's growth stalls completely, and it may stay the same size for weeks while its neighbours double in size.
- Whiteflies on the plant: look on the undersides of the leaves for tiny white flies that flutter up when the plant is disturbed — their presence confirms the route the virus took.
Tomato yellow leaf curl develops over a few weeks after infection. The first sign is often a slight upward curling of the youngest leaves, followed by yellowing between the veins and a slowing of growth. The plant does not die quickly — it lingers, stunted, for the rest of the season, producing little or no fruit while acting as a source of virus for the whiteflies to carry to its neighbours. A plant infected when young is hit hardest and may never produce a worthwhile crop; a plant infected late in the season, after it has already set fruit, may still produce a reasonable crop from the fruit that was already there. The disease is worst in warm weather, when whiteflies are most active, and it can spread through a whole planting in a matter of weeks.
Which plants get tomato yellow leaf curl
Tomato yellow leaf curl attacks tomatoes above all, and it also infects peppers, eggplants, potatoes, beans, and many other plants, along with a wide range of weeds that carry the virus without showing obvious symptoms. The wide host range, especially among weeds, makes the disease hard to eliminate from a garden, because the virus can survive in a weed at the edge of the bed even when no tomatoes are present. All tomato varieties are susceptible to some degree, though resistant varieties exist and are the single most effective defence in areas where the disease is common.
Conditions that favour tomato yellow leaf curl
Tomato yellow leaf curl needs whiteflies, and whiteflies need warm weather — temperatures above about 70 degrees Fahrenheit, with the populations peaking in summer and autumn. The virus itself does not need particular weather, because it lives inside the plant, but the whiteflies that carry it are warm-weather insects, so the disease is a warm-climate problem. The virus survives in infected plants and in weed hosts, so a garden with weeds carrying the virus starts the season with the disease already present. Young plants are the most vulnerable, and plants that are stressed by drought or poor nutrition show symptoms more severely.
How tomato yellow leaf curl spreads
Tomato yellow leaf curl spreads through whiteflies, which pick up the virus when they feed on an infected plant and pass it on when they feed on a healthy one. A whitefly can infect a new plant within minutes of feeding on an infected one, and it stays infectious for the rest of its life. The virus does not spread by touch, by tools, or in seed to any significant degree — it is a whitefly disease, and controlling the whiteflies is controlling the disease. The virus also survives in weed hosts, which the whiteflies feed on and carry the virus from, so weed control is part of the plan.
How to tell it apart from lookalikes
Tomato yellow leaf curl is often confused with herbicide drift, which also curls and distorts tomato leaves, but herbicide damage usually affects many plants at once in a pattern related to wind direction, and it does not spread from plant to plant or come with whiteflies. Nutrient deficiency can yellow leaves, but it does not curl them upward or stunt the plant so severely. Other viruses, such as tomato mosaic virus, also mottle and stunt tomatoes, but they do not produce the distinctive upward curling with yellowing between the veins. If the leaves are small, curled upward, and yellow between the veins, and there are whiteflies on the undersides, yellow leaf curl is the most likely answer, and your local extension service can confirm it from a sample.
Prevention: cultural steps that work
- Grow resistant varieties where they are available — many modern tomato varieties carry resistance to tomato yellow leaf curl virus, and they are the single most effective defence in warm climates.
- Protect young plants with fine insect netting or row covers, so whiteflies cannot reach them while they are most vulnerable.
- Control whiteflies: hose them off with water, encourage predators such as ladybirds and lacewings, and avoid broad insecticides that kill the predators.
- Remove weeds, especially around tomatoes, since many weeds carry the virus without showing symptoms and host the whiteflies that spread it.
- Do not plant tomatoes next to a planting that is already infected, and avoid planting a new crop of tomatoes immediately after an infected one.
- Inspect new plants before bringing them into the garden, and isolate any plant that arrives with whiteflies on it.
- Use reflective mulch, such as silver-coloured mulch, which can confuse whiteflies and reduce the number that land on the plants.
Treatment step by step
- There is no cure for a plant with tomato yellow leaf curl virus. Remove infected plants as soon as you are confident of the diagnosis, and dispose of them with household waste — never compost them.
- Control the whiteflies on the remaining plants, since they are the carriers, and check the neighbours of the removed plant for early symptoms over the next few weeks.
- Keep young replacement plants under netting until they are well established, so whiteflies cannot reach them.
- Remove weeds around the bed, since they can carry the virus and host the whiteflies that spread it.
- Do not take cuttings or save seed from an infected plant, and do not move its soil or its stakes to another bed.
- If the disease is widespread, consider removing the whole planting rather than leaving infected plants to shed virus all season, and replant with a resistant variety under netting.
- At the end of the season, clear all plant debris and wash pots, stakes, and tools that were used with the infected plants.
What recovery looks like
An infected plant does not recover from tomato yellow leaf curl virus — the virus stays in its cells for life, and the plant will stay stunted and unproductive. Recovery belongs to the rest of the garden: plants that were not yet infected may stay healthy if the infected plants are removed promptly and the whiteflies are controlled, and the next planting of a resistant variety under netting should grow normally. The sign that the plan is working is a new planting with large, flat, green leaves that grows at a normal rate and sets fruit normally. That is the point at which yellow leaf curl stops being a recurring disaster and becomes an occasional loss of a single plant, caught early and removed.
When a plant is beyond saving
A plant is beyond saving once it shows clear upward curling with yellowing between the veins and stunting — it will not produce a worthwhile crop and it will spread the virus to its neighbours for as long as it stays. Remove it promptly. A planting is beyond saving when most plants are curled and stunted and whiteflies are active across the bed; in that case, clearing the bed and replanting with a resistant variety under netting is faster and more productive than nursing the infected plants through the season.
Frequently asked questions
Can whiteflies spread tomato yellow leaf curl to my peppers?
Yes, potentially — the virus infects peppers and other plants as well as tomatoes, and whiteflies will carry it to any host they feed on. Keep an eye on the peppers near an infected tomato, and remove infected plants promptly.
Can I eat tomatoes from a plant with yellow leaf curl?
The virus does not make the fruit unsafe to eat, but a stunted plant produces little fruit and it is usually small and poor quality. Remove the plant rather than harvesting from it.
Will the virus survive the winter in my garden?
Yes, in infected plant debris, in perennial weeds, and in whiteflies that survive the winter in warm climates. Thorough cleanup and weed control are the ways to reduce the carryover.
Do I need to control whiteflies if I grow a resistant variety?
It still helps. Resistant varieties can still be infected, though they show milder symptoms and yield better, and whiteflies also damage plants by feeding on them directly. Netting and predator-friendly gardening are worth doing even with a resistant variety.
How can I tell yellow leaf curl from herbicide damage?
Herbicide damage usually hits many plants at once, in a pattern related to wind or spray drift, and it does not come with whiteflies or spread from plant to plant. Yellow leaf curl spreads plant by plant, comes with whiteflies on the leaf undersides, and shows the distinctive upward curling with yellowing between the veins — and check your local extension service if you need a diagnosis confirmed.
Getting help and going further
If you are unsure which disease you are dealing with, take clear photos of the symptoms and check your local extension service — they can confirm a diagnosis from a sample and advise on the varieties and the timing that work best in your area. You can also try our pest identifier helper to narrow down the problem, and browse the guides hub for related disease guides. For growing advice, see growing tomatoes. For growing advice, see growing bell peppers. For growing advice, see growing eggplant. Related guides: mosaic virus plants, bacterial wilt, powdery mildew on cucumbers. Whenever you remove diseased material, dispose of it with household waste — do not compost diseased material, since home compost rarely gets hot enough to kill the organisms that cause these diseases. Good record-keeping helps too: note the date, the weather, and the variety when a problem first appears, so you can spot the pattern next year and act earlier.