10 Tomato Diseases – How to Recognize, Treat, and Prevent?


Any tomato crop can be ruined by diseases. Tomatoes are susceptible to a wide range of diseases at various times during the growing season. 

Logan Hailey, a gardening expert, and former organic farmer examine the most prevalent diseases that are likely to affect your tomatoes in this article. He also explains how to recognize, treat, and avoid these diseases from harming your tomato plants.

Your young tomato plants have been lovingly seeded and cared for, but now the leaves are abruptly turning yellow or the fruits are malformed. Those once eagerly growing plants appear to have been taken over by disease. What the earth is wrong with my tomatoes, you might be asking.

Tomato diseases can be difficult to spot and resolve, whether you’re an experienced gardener or a novice. A little bit of anxiety may be felt when you abruptly realize that all your hard work has been destroyed by an unidentified pathogen.

Don’t fret if you’re craving tomatoes from the garden in the height of summer. There’s still hope! To ensure your tomato plants continue to thrive throughout the growing season, use this straightforward guide to recognize, prevent, and treat the most typical tomato diseases.

1: Early Blight

early blight is damages the leaves of tomatoes.

Early blight on tomatoes is serious. The illness causes targets-like dark areas with yellow bands.  Early blight, caused by Alternaria tomatophila and Alternaria solani, is a common disease of tomatoes and potatoes.

It destroys all above-ground parts of the plant, leaving fragile fruit open to the heat and limiting respiration. Early blight, a fungus disease that begins in the soil, requires replacing tainted soil before sowing new plants. If caught early, early warning signs can be treated to keep your plants healthy.

How to Identify Early blight?

Early blight symptoms include tiny dark brown spots on lower leaves. As the spots grow, a golden band forms around them, giving them a target-like look. 

Leaves rust and brown before falling off, spreading the illness quickly. The stem may also have faded, dead leaves.

How to Prevent Early blight?

Although some tomato varieties are immune to early blight, the best ways to prevent it are to improve airflow, reduce leaf dripping, and follow crop cleaning protocols. 

Tomatoes must be spread farther apart (usually 24-36″) depending on type and lattice. Regularly trim lower stems.

Avoid aerial soaking and use soaker lines or drip irrigation to wet the roots. At the season’s end, clean up tomato waste. Tomato refuse from previous crops causes illness. Infected seeds or cuttings can spread the illness.

How to manage?

Tomatoes with early rot have several options. Discard affected parts first. Avoid gusty or wet weather because spores spread. Sanitize your hands after pruning. 

To cure and prevent spread, add a mild neem solution. Baking soda mist works too. (1 tbsp baking soda, 1 tsp veggie oil, and 1 tsp mild soap in a gallon of water).

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2: Late Blight

late blight is contagious to tomato leaves and stops the growth.

Remove any plants that have been lightly infected from the region right away to stop the spread of late blight.

Late blight, in contrast to early blight, is not brought on by a pathogen. The secret offender is water mildew called Phytophthora infestans. The Irish Potato Famine is its most famous impact.

Even though there is little chance of a national tomato famine, late blight can still seriously harm a crop. This is why it’s crucial to use sterile gardening equipment and disease-resistant plants. 

Pay close attention to your plants to spot any early warning signs because they can spread quite rapidly.

How to Recognize Late blight?

The foliage initially appeared to be sopped in water. The patches then grow into oily blotches that are purple in color. On the underside of the leaves, you might observe outer rings that are fuzzy and gray-white. (this is the mycelia). 

Petioles and entire leaves will start to drop off. Infected fruits can also develop dark spots near the tomato “shoulders,” for example.

How to Avoid Late blight?

Late blight can start in as little as 10 hours at high humidity and moderate temps (60-75°F). Any plants that have a slight infection must be ruthlessly removed from the land. Make sure to fully clear the garden of any crop residue from previous nightshade family crops each year. In the future, choose blight-resistant types.

How to manage?

Given how quickly it spreads, late blight is a challenging condition to treat. The growth of the disease cannot be stopped, but you can slow it down with preventative fungicides like copper, sulfur, or for maximum safety neem oil.

3: Blossom end rot

blossom end rot is caused by deficiency of calcium.

Regular irrigation and keeping the ideal calcium level are essential for preventing this disease. Blossom end rot resembles a pathogen even though it isn’t actually an illness. This physiological condition is actually brought on by a lack of calcium in the earth.

They must be taken out and thrown away once it has a grasp of the fruit. For gardeners who have devoted a lot of effort to keeping their tomatoes living all summer, this can be disappointing. Thankfully, with the right soil nutrients, this incurable tomato condition can be readily avoided.

How to Recognize?

Where the flower once was, the bottom extremities of fruits have a rotten appearance and appear black, grey, or sunken-in.

How to Avoid?

The key elements in avoiding this issue are regular watering and appropriate calcium levels. Utilize a soil test and add lime, bone powder, or eggshells as needed. Make sure that the plants are not under water or heat duress.

How to Manage?

A berry cannot be saved once the rot at the end has started. To preserve future harvests, get rid of the harmed tomatoes and work to address the underlying problem.

4: Botrytis (Gray Mold)

grey mold is caused with the excessive humidity in air.

Gray mold is growing on red tomato fruits. Fruit develops botrytis when the humidity level is excessive. 

This colorless mold is the gardener’s worst nightmare! In areas with high humidity, the botrytis fungus can infect a variety of products, including tomatoes, squash, and grapes. The post-harvest rotting of tomatoes in the grocery store or on the kitchen table is typically caused by it.

While it is difficult to control the air humidity when growing tomatoes, you can control how the plants are spaced when they are buried. To guarantee proper airflow, you can prune them as well. Additionally, it’s a good idea to avoid watering vegetables from above.

How to Recognize it?

Typically, immature tomato fruit and flowers are covered in the gray mold first. It appears to be circular white patches that will eventually change yellow.

How to Avoid Gray mold?

With tomatoes, never use overhead watering. If you live in a humid environment, space your plants farther apart and prune them more frequently to improve air circulation.

How to Manage?

Remove any leaves or fruit that have been infected with gray mold if the illness is severe. Clean your palms and the pruners. To eliminate any spores and stop further illness, use neem oil, horsetail (Equisetum) spray, or a diluted fungicide.

5: Powdery Mildew and White Substance 

powdery mildew caused in summers

Maintaining airflow and regularly cleaning the garden will help to stop the illness from spreading.

While tomato foliage is also frequently attacked by powdery mildew, zucchini, and cucumbers are the fungus’s most well-known casualties. 

The worst mildew infections typically occur in the middle of the summer when it is hot, dry, and particularly when there are moist, cool nights.

Another fungus-related illness on this list is powdery mildew. A good method to avoid this disease is to water your garden properly from below and to keep it well-maintained. However, it has the potential to sneak up on almost any vegetable plot.

How to Recognize Powdery Mildew?

Powdery mildew makes your tomato plants appear as though they have been dusted with gray or white flour. There may be a golden halo surrounding circles of dead tissue.

How to Prevent?

Resistant types (designated “PM” in seed catalogs) are typically the simplest form of defense. Cultural controls like clearing crop debris, removing pruning, keeping airflow, and avoiding overhead irrigation should also be a priority.

How to Manage?

One of the safest and most efficient sprays for powdery mildew is the bio fungicide Bacillus pumilus. However, before using fungicides, the majority of landscapers eliminate infected foliage, prune additional leaves, and then apply a diluted neem solution.

6: Fusarium wilt

Fusarium wilt is dangerous to tomato plants.

The “yellow flag effect” is this disease’s most defining symptom. Fusarium oxysporum lycopersici is the fungus that is responsible for this catastrophic wilt. 

It is impossible to treat fusarium wilt. Purchasing tomato seeds that are disease-resistant is the secret to escaping their terrible fate. Fortunately, there are many tomato types available that were developed to be disease-resistant.

How to Recognize Fusarium wilt?

No matter how much water is given to infected yellowing foliage, they quickly wilt. The “yellow flag effect,” in which only one side of the plant wilts while the other side stays green and healthy, is the most notable feature of this particular disease.

How to Avoid Fusarium wilt?

Growing resistant varieties is the greatest form of prevention. ‘Big Beef Plus’, ‘Sun Gold’, ‘Better Boy’, ‘Beefmaster’, or ‘Early Girl’ are a few of our faves.

In your tomato patch, you should also manage root knot nematodes because they can harm plant stems and make them more vulnerable. White mustard and marigolds are two partner plants for tomatoes that can aid in nematode suppression.

How to Manage?

Fusarium wilt is, regrettably, fatal. It can persist for many years on the earth and turn permanent. By removing contaminated plants and a portion of the infected garden soil, you can stop the spread. After handling this pathogen, always rinse and sanitize gardening equipment and footwear.

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7: Fusarium root rot

Fusarium root rot effects the roots of tomato plants.

In waterlogged soils, fusarium root decay spreads most quickly. It is harmful to have this root infection, just like a fusarium wilt. The spores have a long lifespan and have an impact on a broad range of crops and weeds. 

It is crucial to use well-draining soil when sowing and to ensure that you are watering your tomatoes at the right rate because they particularly enjoy waterlogged soils.

This ailment starts at the plant’s base and spreads to the stem, leaves, and fruit as it grows. Yellowing leaves could be the first indication of an illness. The plant will most likely need to be dug up and disposed of once it begins to exhibit signs.

How to Recognize?

Fusarium root rot causes wilting and stunting by attacking the roots of immature or frail plants. The oldest leaves above earth start to exhibit symptoms first. They quickly pass away after beginning to turn yellow around the margins.

How to Avoid?

By adding a lot of organic matter, broad forking frequently, and avoiding tillage, you can maintain correctly aerated, well-drained soil. Don’t water vegetables excessively. Select resistant cultivars like “Supersweet 100,” “Cherry Bomb,” “Sakura,” or “New Girl” (labeled “FOR” in catalogs).

How to Manage?

There is no recognized treatment for this illness. The key is to exercise sterilization and prevention.

8: Black Mold

black mold happen if it rains alot and vegetables get to much moist.

Avoid overhead irrigation because black mold prefers wet produce. This nasty disease can abruptly attack ripe tomatoes hanging on the vine if there are a lot of late-season rains. It is brought on by the fruit-loving fungi Alternate alternate.

While we have no control over the weather, we do have control over how we water our tomatoes. Vegetables, including tomatoes, should always be watered from the bottom up! This will aid in halting the proliferation of mold or fungi-related illnesses.

How to Recognize Black Mold on Tomatoes?

On tomato fruits, you will see dark, velvety lesions when it is balmy and humid outside. These will develop into sunken, circular lesions that rot mature produce.

How to Avoid?

Harvesting your tomato fruits just before they completely ripen is the simplest form of prevention. (especially if rain is on the way). Avoid overhead watering at all costs, especially in the late summer. Fruit should be kept as dry as feasible.

Fruits should also be kept covered beneath leaves in an effort to prevent sunburn. Clean up any infected or dead sections from the garden.

How to Manage Black Mold?

Black mold may need to be killed in wet years using both organic sprays (like neem) and traditional fungicides (like calcium chloride).

Fruits must be completely washed before consumption, though. It is much simpler to pick them up a little early and let them ripen in your kitchen next to bananas.

9: Tobacco Mosaic Virus

Tobacco Mosaic Virus effects the leaves of plants.

A mosaic design on the leaves is one sign of the Tobacco Mosaic Virus. The tobacco mosaic virus (TMV) affects tomatoes as well as all of the tobacco’s relatives that are nightshades

Unfortunately, studies have shown that this persistent virus can remain in dead, dry plant debris for up to 100 years.

This is why it is so important to get rid of any sick, diseased, or dying plants. By keeping them around, the virus may persist on the earth. Additionally, don’t discard it! It will endure in the compost mound and spread to other garden plants.

How to Recognize?

The defining sign is a mosaic-like design on tomato leaves. The foliage may wilt, curl, and take on fern-like characteristics.

How to Avoid?

Never use tobacco goods or smoke in the vicinity of your tomato plants. Select disease-resistant cultivars (designated “TMV”) and make sure to buy your seeds from a reputable, disease-tested seed business.

How to Manage?

Treatment for TMV is not possible.

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There are many things that can go wrong with tomatoes. When you read lists like the one in this article, it can be scary to think about how to grow them.

But keep in mind that if you make the right environment and grow well, you are much less likely to run into these problems, and if you do, many of them will probably be easier to deal with.

Don’t let that get you down. Attempt to grow tomatoes. You will face problems. But it’s also true that you can have a lot of fun while doing it!

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