Black Edges On Tomato Leaves: Remedies and Cure

black edges on tomato leaves
black edges on tomato leaves

A homeowner can grow tomatoes in a small garden space, which is one of the most nutritious crops available. Nevertheless, they must be regularly watered and monitored to avoid the many pests and diseases that can wreck healthy tomato plants in their prime.

In addition to potassium, niacin, folate, and fiber, tomatoes are also high in antioxidants. These compounds help protect your heart. By taking care of plants in your garden, you get to exercise your cardiovascular system.

Every year, gardeners grow tomato plants, one of the most popular fruits and vegetables. Their unique characteristics make them a popular choice. In botanical terms, tomatoes are fruits. The edible portion includes reproductive structures (seeds). The tomato is a very delicate plant and is subjected to many diseases.

The most common disease in tomatoes is black edges or spots on leaves and other parts of the plant. This disease is widespread among various types of tomato plants worldwide. This article will guide you about reasons, identification, and remedies for black edges on tomato leaves.

Black Edges On Tomato Leaves: The Reason

Commonly the cause of black edges in tomato leaves is fungal disease or infection. A fungal or bacterial infection’s symptoms include black spots on leaves, stems, and fruits. Plants suffer harm and even die as a result of these airborne or soil-borne pathogens.

There can be many causes of black edges on tomato leaves. Some of them are explained below. The most common diseases that cause black edges on tomato leaves are a late blight, early blight, bacterial canker, and Septoria leaf spot.

Late Blight

Late Blight

This type of blight occurs less frequently and has a greater destructive capacity. Wet weather or high humidity combined with cooler air temperatures (60 to 78°F) leads to this blight.

As a result of airborne Phytophthora infestans spores, healthy vegetables are infected for three to five days, thereby causing the health-threatening late blight disease.

The small irregular lesions are first seen on the older leaves (lower leaves) and eventually spread to the stem and fruit. Fungi cover the leaves, stems, and fruits.

Water-soaked or bruised areas may appear around lesions, and the spots may turn yellow or green. Late blight reproduces rapidly, causing spots to overgrow.

Early Blight On Tomatoes

Early Blight On Tomatoes

Symptoms of early blight include round, concentric spots on leaves, which have a distinctive target appearance due to the dark concentric rings around the spots. Each spot is approximately one-half inch in diameter.

Also, the cause is a fungus that affects stems and fruit. A stem lesion at the base of the stem can kill young seedlings.

Pathogens are typically spread by seeds infested with the pathogen, debris left on the ground from infected plants (where it can survive at least one year), or spores of other infected plants dispersed by wind, water, insects, or animals.

Bacterial Canker

Bacterial Canker

Commercial and home garden plantings can be affected by bacterial canker, a potentially serious disease of tomatoes. A tomato plant of any age can suffer from the bacterial spot; all parts above ground are at risk.

Small, waterlogged lesions on the foliage, stunting and wilting are the symptoms of seedling wilt. Bacterial canker often results in the death of young plants.

Once symptoms are evident, it is difficult to treat bacterial canker. The best strategy is to prevent disease in the first place. Irrigate early in the morning in the greenhouse or in the field, so the foliage is not wet for long.

Black Edges On Tomato Leaves: Remedies And Cure

Tomatoes planted too close to one another are the most frequently made mistake by gardeners. To prevent any disease from spreading, you need to plant your tomato plants far apart.

For disease prevention, plant them around 18-24 inches apart. The same goes for growing tomatoes in the same place year after year. To prevent replanting them into infected soil, rotate them around your garden.

Plant debris and soil can provide living spaces for disease-causing organisms throughout the winter and for some years. You can also prevent black leaf spots on your tomato plants by purchasing disease-resistant seeds.

Wide varieties have been bred to make tomatoes resistant to diseases such as blight. Most seed packets will include this information. If there is good airflow, any spores present will be less likely to germinate as quickly after the plant has been wet.



It may not be necessary to prune certain tomato varieties. Pruning will be your best defense when you discover Septoria. As soon as you find out infected leaves, you should remove them immediately to prevent the spread of the fungus.

Spores grow on the leaves and spread the fungus. Black leaf spots may not spread if removed early enough. As part of its preventative and treatment functions, pruning increases airflow.

Fungicide Treatments

Fungicide Treatments

Fungicides can be used on severely infected plants. Aside from stopping the spread of infection, they cannot cure leaves that are infected. Septoria leaf spot can be treated with almost all the fungicides commonly used on tomatoes.

Bonide Fung-onil Concentrate is a popular and readily available product. A classic Bordeaux mixture is always a good choice if you want an organic fungicide.

Copper and sulfur are ingredients in this mixture that have been used to control fungi since the 1800s. They can also be helpful in treating this problem in your tomato plants.

Mechanical treatment

Mechanical treatment

A sterile pruning tool is usually used to remove infected branches. In most cases, bacterial canker is treated mechanically.

For prevention of reinfection by bacterial spot, wait until late winter and cauterize the wound with a hand-held propane torch. By peeling back the bark on infected branches, you’ll be able to see where the canker ends clearly.

Cultural Controls

Plants need a mulch covering under them, which can be made of fabric, straw, plastic mulch, or dried leaves. Use drip irrigation, soaker hoses, or water carefully by hand.

It can also help prevent early blight from spreading via splashes from the soil onto leaves when the bottom leaves are pruned. Do not plant tomato plants or pepper plants in the same area for two years.

Proper Sanitation Measures

It is possible to prevent spores from spreading to the next crop through proper sanitation measures. It is recommended that tomato husks and waste should be removed at the end of the growing season and thrown away, composted (if the pile is hot enough to kill the spores), or incorporated into the soil.

Keeping the spores below the soil surface and away from tomatoes is accomplished by completely burying the residue.

Crop Rotation

Tomato plants can also be disease-reduced by using crop rotation. Planting tomatoes in new places annually avoids the spots where eggplants, potatoes, and peppers were previously grown.

The disease problems they all have are similar. To reduce soil-borne fungus populations, a rotation of a minimum of three years is recommended.

Preventing Tomato Leaves From Turning Black

Selecting disease-resistant tomato varieties is one way to prevent blackened leaves on tomato plants.  Some seeds state, for example, that they are resistant to blight.

The tomato plants shouldn’t be planted in the same spot yearly, primarily if you use the same soil.  You should thoroughly wash your tomato pots after the season ends if you planted them in containers.

Winter is the ideal time for the disease to hide in the soil and lie dormant, ready to pounce on your new crops.  Those concerned with protecting their plants from disease even go one step further.

The seeds of tomato plants can be killed by soaking them in 180 degrees Fahrenheit water for 30 minutes before planting.

Pick Reliable Tomato Varieties

Pick Reliable Tomato Varieties

It’s imperative to plant tomatoes from reliable and resilient sources when you first plant them. Tomato seed providers sell varieties bred for blight resistance and other disease resistance.

Use transplants only if no signs of blight are visible on the plant tissue. During planting, the entire plant must be free of blight to prevent future infestations.

Use The Right Compost Pile

Generally speaking, you shouldn’t use plant debris from a tomato crop for composting your next crop. Specifically, if your tomatoes suffer from diseases like blight, you should avoid composting them to prevent fungal spores from re-infecting your plants next year.

The Bottom Line

Though tomatoes are vulnerable to many diseases and fungal attacks, there are several ways to stop and treat these problems. Black spots on the edges of the leaves and other parts are widespread among these problems.

You should try the above methods to prevent and treat your tomato plants’ fungal attacks that cause black spots.

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