How to Identity, Control & Prevent Early Blight of Tomato Plants

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Quick Answer: Early Blight of Tomato Plant

Tomato plants are sensitive to climate change and undergo Early Blight infection because of warm temperatures and heavy rainfall. Early blight is a defoliating infection that usually spreads from the contact of contaminated soil to leaves; reaches the stem and then fruits. Early blight is a very common infection for tomato plants with no complete recovery but can be managed by fungicides and some basic disinfecting measures.

This is your comprehensive guide on the Early Blight of tomato plants.

Let us get started!

What is Tomato Early Blight Disease?

Early Blight infection of Tomato plants is a fungal disease caused by different yet closely related species of fungi Alternaria tomatophila and Alternaria solani.  

Tomato plants are prone to Early Blight infection when favored by warm temperatures, heavy rainfall, and high humidity [ high moisture content]. The temperature not considered suitable for tomato plants’ health ranges between 75- 84 degrees Fahrenheit.

Early Blight disease is a defoliating pathogen; it affects foliage [leaves of tomato plants] after contacting contaminated soil.

Initially, it leaves a dark brown spot in the bottom of leaves which later grow into deep, concentric circles.

Early Blight disease infects tomato plants irrespective of season, age, and health.

However, older tomato plants and plants with poor health are more prone to this disease and are likelier to perish.

Early blight is not a deadly infection rather,it affects the quality and quantity of fruits.

How Early Blight Harm Tomato Plants? 

The fungi Alternaria is found in infected soil. It lives in the ground for about 3 to 4 years and can infect plants during this time.

The spores of Alternaria reach the leaves of the tomato plant either by direct contact with leaves and soil or by water splashing. Heavy rain and overhead watering cause the water containing debris of contaminated soil to splash. 

It then infects the bottom of leaves; completes its life cycle, and transmits the infection to the whole plant. The germination of fungi spores slows the process of air circulation, making the plant weaker by each day.

Humans contribute significantly to the spreading of the disease. Early Blight infection is highly contagious and, thus, spreads to healthy plants when we touch the infected plant with bare hands.

How to Confirm that Early Blight is Troubling your Tomato Plants?

The initial sign of Early Blight infection is found on the bottom of the leaves. Small and dark brown spots followed by deep, brown lesions type concentric rings which look like ‘bull’s eye.’ The diameter of these spots extends up to half an inch.

The yellow area surrounding the concentric lesions indicates the last stage of infection. Later, in this stage leaf turns brown, sunken, dry, and dies.

Brown Concentric patterns  on Foliage

Early Blight disease infects every Tomato plant, including stems and fruits. These parts of the tomato plant can get exposed to an early blight during any stage of growth development. 

It is during the ‘ Concentric Rings’ stage of infection Alternaria starts to infect the stems of the plant. 

Observe the following symptoms in the stems of tomato leaves- 

  • The lesions of the stem resemble the lesions formed on the foliage of the tomato plant. These lesions are oval concentric, and dark brown. 
  • These lesions encircle or girdle the stem of the tomato plant. 
 Brown Wilted stem

Early Blight infection spreads from stems to fruits causing the same ‘ Concentric ring lesions’ on them. The infected area of fruit becomes sunken, leathery, and loose.  

These symptoms expose the plant naked, therefore damaging healthy fruit due to sunscald. 

Ways to Control Early blight Disease on Tomato Plants

Early Blight infection can happen to any tomato plant, and its complete recovery is less likely to happen. However, practicing some critical gardening tips can prevent and manage the spread of disease.

1. Avoid Splashing water by adopting these simple techniques

Construct narrow Trenches alongside your tomato plant to ensure that water enters the plant’s root.

This method is helpful in the long run because it assures that no foliage gets wet and the plant gets enough water. 

Check out this video on how to trench your tomatoes-

2. Mulching

Support your beautiful tomato plant roots by Mulching. You can mulch the tomato plants either with organic matter or plastic sheets. 

Mulching serves a dual goal – 

  • It maintains a required distance between foliage and soil.
  • It soaks the water and prevents the water from splashing. 

3. Staking & Caging

Staking is another effective way to ensure good air circulation and contact between infected soil and the leaves of plants.

It also facilitates the drying of wet foliage. Stakes constructed should be 1m deep in the soil.

Caging up your tomatoes so that they don’t touch the leaves or the stem of the plant directly.

Check out this video on how to stake, Mulch, and trench your tomato plants easily-

4. Use Disease Resistant varieties

Resistant Varieties are a good way of controlling the disease.

Good quality seeds are not immune to Early Blight disease but will pick up the infection late and might pause the further life cycle.

5. Spray Fungicides

It is always good to spray fungicides during the rainy season.

Still, working with preventative fungicides will always be the final step in managing your tomato plants against Early Blight. 

Fungicides must be used very accurately. Following the instructions written on the label is a prerequisite before spraying fungicide. 

The amount of fungicide to be used, environmental conditions that favor its application, when to be used, and the time interval between two applications are the significant checks before fungicide application. 

Spray a fungicide when the first sign of disease becomes apparent.

Check out this video to learn proper guide to spraying fungicide-

Using an organic or homemade fungicide is a good approach for disease management and good quality of tomatoes. 

You can make a good fungicide easily at home by mixing water, bicarbonate of soda, and vegetable oil in a ratio of 2:1:1.

Mix and shake it well in a spray bottle and spray it evenly on your tomato plants. Make sure you cover every part of the plant part.

How to Prevent Early Blight on Tomato Plant

Prevent your beautiful red tomatoes from Early blight by adopting some very simple points.

1. Restrict the spreading of infection onto the Healthy Tomato plant

The source of infection in healthy tomato plants is always either human contact or touch of diseased parts. 

  • Remove the dead leaves from the ground.
  • Eliminate overhanging infected leaves from the plant. 
  • Spray fungicide on the foliage, stems, and fruits. 
  • Do not touch healthy tomato plants without disinfecting your hands. Disinfect the appliances that remove the infected leaves in bleach and water solution.  

2. Observe the Tomato Plant’s Health 

Keeping track of your plant’s health helps in recognizing the early signs of disease.

  • Monitor your plants very carefully.
  • Provide them with enough space for air circulation. You can do this by maintaining a gap of 1 foot between leaves and soil and keeping a distance of about 50 cm between two plants. 
  • Do not wet the leaves of the plant. This could favor the spread of disease.
  • Spray the fungicide as soon as the first signs of infection are spotted. 
  • Do not work with your plants when they are wet.

Check out this video for managing early blight-


What is the best fungicide for early blight on tomatoes?

You can use organic fungicides containing neem oil and other natural ingredients.
You can also work with homemade fungicides. 

What time of day is suitable for spraying fungicide?

Evening time or nighttime is considered suitable for spraying fungicide. It gives your plants to absorb fungicides in a better way. During the daytime, its application would not be a good choice since the sun’s heat can burn the leaves. What time of day is suitable for watering the tomato plant?

Can I reuse soil after tomato early blight?

I wouldn’t advise you to reuse the infected soil because the spores of Early blight live for 3 to 4 years and can re-infect other healthy plants.

Can I put the dead leaves of early blight infection in compost?

No, composting the infected leaves can contaminate your soil and might infect the healthy plant in the future. You should either put them in a burn pile or throw them away.


I really hope this information will help you in the identification, prevention, and management of Early Blight.

Feedbacks and suggestions are always welcome! 

Also, share these easy tips with your friends and family.