Skip to Content

Prevent and Treat Early Blight on Tomatoes Full Guide of 2023

This site is supported by our readers. We may earn a commission, at no cost to you, if you purchase through links.

how to prevent treat early blight on tomatoesAh, the dreaded early blight on tomatoes. It’s a problem that plagues many home gardeners – and it can be downright discouraging when your harvest is reduced due to this pesky fungus. But don’t despair! There are some effective ways to prevent and treat early blight on tomatoes so you can get back in business quickly with healthy plants and juicy fruits.

In this article, we’ll examine what causes early blight, how to identify it, organic treatments for prevention and treatment of the disease, as well as fungicides available for use in controlling tomato diseases like Early Blight.

So let’s learn how to keep our precious tomatoes safe from harm!

Key Takeaways

  • Properly space plants and stake them to prevent early blight.
  • Use organic fungicides like baking soda, neem oil, copper sprays, and garlic spray to treat early blight.
  • Rotate crops every two years and eliminate nightshade plants to reduce fungal spores in the soil.
  • Maintain dry conditions by watering at the base of plants, using mulch around plants, and avoiding overhead watering, which can spread spores.

What is Early Blight?

What is Early Blight

  • Get acquainted with early blight, a fungus that can wreck your tomatoes. This disease causes dark spots on leaves that expand into brown patches as it spreads up from lower foliage.
  • Early blight comes from a fungus called Alternaria solani. It impacts tomatoes and potatoes. Look for small dark spots on older leaves. These expand into large dead brown areas. Infected leaves often yellow and drop off.
  • Seedlings may show brown, dry rot on their stems. Mature plants can develop dark leathery spots on fruits.
  • To prevent problems, space plants with plenty of room and mulch to reduce soil splash. Avoid overhead watering. At the first sign of spots, use an organic fungicide weekly. Remove and destroy any heavily infected plants.
  • Rotating crops and cleaning up debris after harvest also helps reduce this stubborn disease next season.
  • With close monitoring and quick action when you first notice issues, you can still get a good tomato harvest despite early blight in the garden.

Symptoms of Early Blight

Symptoms of Early Blight
Seemingly insignificant dark spots on lower leaves signal early blight’s stealthy spread. Lesions start as small, dark spots on older foliage. Spots enlarge into ringed, circular dead areas up to half an inch wide.

Lower leaves yellow, wither, and drop off. Stem lesions form dark, sunken, dry areas.

Though early blight runs rampant when conditions favor disease, attentive gardeners can stay one step ahead with vigilance and timely action. Scouting regularly, removing infected plants promptly, and maintaining best practices for plant health and hygiene limit opportunities for infection.

Strategic fungicide applications at initial symptoms and fruit set boost defenses when environmental risks are high. An ounce of prevention truly protects plants from pounds of cure against this ruthless destroyer of tomatoes.

Cultural Controls for Early Blight

Cultural Controls for Early Blight
To prevent early blight on your tomatoes, start by rotating crops every two years and removing nightshade plants as well as volunteer tomato plants. You’ll also want to stake your plants to improve airflow and keep foliage as dry as possible by watering at the base and avoiding overhead irrigation.

Crop Rotation

After the devastation of early blight last season, rotating crops every three years keeps you a step ahead. This prevents fungal spores from building up in the soil. Companion planting tomatoes with disease-resistant beans or basil boosts beneficials.

Mindful crop planning sustains plant vigor and suppresses blight pressure. Careful rotation coupled with mulching and resistant varieties makes controlling early blight achievable.

Eliminating Nightshades and Volunteer Tomato Plants

Pulling nightshades and stray tomatoes deprives blight of hosts on which to build strength. Nightshades like potatoes and peppers harbor the fungus, enabling disease to persist. Uproot and discard volunteer tomatoes as they appear to block transmission. Vigilant garden maintenance curtails blight before it can take hold.

Eliminating alternate hosts limits the pathogen’s foothold. Stay on top of nightshade removal and stray tomato plants to prevent and treat early blight on tomatoes.

Maintaining Dry Conditions

To maintain dry conditions for your tomato plants, stake or prune them for good airflow. Controlling soil moisture through drip irrigation and mulching around the plants helps reduce humidity levels. Allow adequate space between plants, trellis vines if needed, and selectively remove leaves to promote air movement.

Breaking the disease cycle requires managing moisture in the soil, on plant surfaces, and the humidity around the vines. With proper spacing, staking, and mulch, you can create the drier conditions that deter blight.

Organic Treatments for Early Blight

Organic Treatments for Early Blight
Spray your tomatoes weekly with a homemade baking soda solution to inhibit early blight’s development. Neem oil, copper sprays, and garlic spray are all effective organic treatments. Mix one tablespoon baking soda and one-half tablespoon vegetable oil with one gallon water.

The oil helps the solution stick and spread over the entire plant. Spray leaves, stems and surrounding soil to disrupt fungal growth.

Boost plants’ defenses by side dressing with rich organic compost around the base. At first sign of early blight, increase spraying to twice a week. Consistent applications will prevent fungal infection without harsh chemicals.

When using organic methods, vigilant monitoring and proactive care is key to controlling tomato diseases. With early identification of leaf spots and rapid response, your plants can thrive disease-free all season.

Fungicides for Early Blight

Fungicides for Early Blight
While organic treatments can be effective against early blight, fungicides offer the most powerful solution for protecting tomato plants. When applying fungicides, focus on key timings to maximize efficacy-targeting the periods just before and during initial infection when conditions favor disease development.

Compare products for effectiveness on early blight and select targeted, mobile fungicides that provide protective and curative activity.

Apply directed foliar sprays for coverage of stems, undersides of leaves, and developing fruit. Fungicides stop the disease from establishing so you can still harvest healthy, bountiful tomatoes despite early blight pressure.

How to Identify Early Blight

How to Identify Early Blight
Lead your eyes to the scattered polka dots marking the leaves, as Time’s steady march blackens what was once green.

  1. Examine underneath the leaves first – this is where early blight starts.
  2. Look for small, dark spots ringed by yellow halos. These expand into larger lesions.
  3. Check the stems too – sunken, dark lesions may appear.
  4. Scan developing tomatoes. Leathery black spots mean infection.

Differentiate early blight from other fungal diseases by its distinctive target-like markings. Catching it early allows for treatment to protect your tomato crop and prevent significant losses. With vigilance and swift action, you can gain the upper hand against this stubborn fungal foe.

Prevention and Treatment of Early Blight

Prevention and Treatment of Early Blight
Stop the rot by rotating your tomatoes every two seasons! Prevent early blight’s spread by using disease-resistant tomato cultivars, moisture management, and preventive fungicide applications. Rotate crops religiously, as the fungi overwinter in the soil. Space plants properly and stake them for better airflow.

Scout regularly and promptly pull infected plants, disposing of all debris. Apply appropriate fungicides preventatively, especially copper sprays, during damp periods when the fungi thrive. Explore organic solutions like baking soda sprays or homemade biofungicides with garlic-chili-soap.

The most vulnerable seedlings need special protection. With vigilance and an integrated strategy, you can thwart early blight and enjoy bountiful harvests.


Prevention is the best cure when it comes to early blight on tomatoes. As an experienced home gardener, you’re aware that this fungal disease can rapidly devastate a tomato crop. Alternaria solani, the fungus accountable for early blight, can spread through wind, water, insects, and clothing.

So it’s vital to take action early. Start by rotating tomato crops every two years, removing nightshades and volunteer tomato plants, and keeping plants dry. Staking plants for airflow and using organic treatments or fungicides preventatively at fruit set can also help halt the spread of the disease.

Identifying early blight is crucial, as you’ll need to remove and destroy infected plants. With the proper precautions, you can safeguard your tomato plants from early blight and enjoy a fruitful harvest of ripe and juicy tomatoes.

Avatar for Mutasim Sweileh

Mutasim Sweileh

Mutasim is a published author and software engineer and agriculture expert from the US. To date, he has helped thousands of people make their yards lush and thick.