How to Prevent Tomato Blight

A vegetable garden, beginners, are proud of can be hit by different problems throughout the year. One of the best vegetables to grow is tomatoes, but these can easvegetable garden, beginnersily be hit by the disease.

Here we will take a look at tomato plants and see the most common disease they are hit by, and how to get over it.

Tomato BlightWhat is Tomato Blight?

What is tomato blight? This is a fungal infection that is spread like any other fungi, by spores. These plant diseases are actually three different kinds that can hit growing tomatoes in various ways.

Now we can see what it is, we need to understand what causes tomato blight because without knowing this, we are unable to treat the plants and prevent it.

To bread and spread, these spores require damp, warm weather conditions. These are ideal for them thriving and passing around other plants with ease

Types of Tomato Blight

Septoria BlightSeptoria Blight

This is also known as leaf spot, is the most common variety of blight you can get on tomatoes. This usually begins to appear toward the end of July.

You can easily recognize it from the small black or brown marks that appear on the lower leaves. Septoria leaf spot symptoms usually appear first on older leaves, after fruit begins to ripen.

In many occasions, the fruits remain uninfected, but, the loss of leaves will affect the yield you can receive, as well as exposing the fruit to sunscald. Luckily, this is the least harmful form of blight in tomatoes.

One of the ways to combat this is to water the base of the plants rather than the leaves and to also avoid the garden while the foliage is wet.

To further this, you can grow tomatoes in a raised bed that allows for better drainage, and it can keep your tomato problems segregated.

Early BlightEarly Blight

The Fungus Alternaria solani is a fungal pathogen and appears after there is heavy fruit set. Early blight: symptoms appear on older leaves that are near the base of the plant, and you will also see the target-like appearance of concentric rings.

These then move to the cankers and are quickly followed on the stems.

Black spots on the nearly ripened fruit turn into spots that look like large bruises, and the fruit begins to fall.

Because crops are almost ripe for the picking, this can be the most disappointing time to see tomato blight.

The treatment for this is simple, and the way you can prevent tomato blight from reemerging on next year’s crop is to burn as much as you can that the fungus might have touched. This will include any fruit or foliage.

Late blightLate blight

The fungus, (Phytophthora infestans), is aptly named: Phytophthora, and means “plant destroyer.”

Late blight, is a disease that strikes tomatoes and potatoes. This is the least common blight on tomato plants, but, by far, it is the most destructive.

It is vital that gardeners understand late blight isn’t like any other tomato and potato diseases.

You will see pale green, water-soaked spots on the leaves, and these quickly turn into dark spots. Additionally, stems also turn black.

Fuzzy growth on the underside of leaves indicates late blight caused by the fungus is growing and producing blight spores.

This attacks growing tomatoes in wet weather, and when the nights are cool. It has a rapid effect and quickly infects plants which will soon rot.

This blight was first encountered with the Great Potato Famine of the 1840s. At this time an infected potato plant would quickly infect neighboring potatoes.

All potatoes need to be disposed of, as should all tomato plants affected by this type of blight.

This tomato blight cure is straightforward, and all it takes is to burn everything the fungus may have touched.

Preventing Tomato Blight

Once there is this blight on tomatoes, fungus of this type is hard to control.

  • Once identified, tomato blight treatment begins with fungicide treatments.
  • Solutions really lie in prevention, and using fungicides before the fungus appears, should be applied throughout the season.
  • Rotate crops as when possible and never mix any tomato debris back to the soil.
  • Remove damaged lower leaves when they turn yellow because this is where most fungi attacks start.
  • Remove all plant debris at the end of the growing season, and deeply till the garden at the end of fall. This is the best soil treatment for tomato blight and gives no place for the spores to go over the winter.

Be Prepared

A USA blight web site helps track late blight in real time. Check this website regularly in the growing season. If late blight is detected in your area, consider weekly preventative sprayings.

5 Gardening Tips to Prevent Late Blight

The key is to plant carefully, be prepared, being alert and learning to distinguish late blight from other common plant diseases such as blossom end rot.

  • Choose the right type: No tomato varieties are immune to late blight. Plant breeders are developing varieties which are resistant to infections by the late blight fungus. You can try to plant some varieties which mature early, so they harvest before late blight does strike.
  • Prevent overwintering: Fortunately, the blight fungus needs living tissue to survive during the winter, and infected potatoes can carry this disease. Destroy volunteer potato plants which come up. If planting potatoes, be sure the seed potatoes are certified disease-free.
  • Give plants space: If possible, rotate crops and don’t plant tomatoes and potatoes in the same area as last year. Plants need plenty of space, so maximizing airflow and light around plants helps resist disease.
  • Avoid watering from above: Soaker hoses or drip irrigation will keep leaves dry, this makes it harder for late blight to spread. Try not to use sprinklers. Water early so foliage can dry before nightfall.

As you can see, there is not much you can really do once early, and late tomato blight sets in, and the only real cure can be prevention.

Being aware of what it looks like, and how to make sure it doesn’t spread are a gardeners best defense when they plant tomatoes.

How to Prevent Tomato Blight

5 thoughts on “How to Prevent Tomato Blight”

  1. It might be helpful to list a few of the more resistant varieties of tomatoes. You might list them by type i.e., yellow tomato’s, tommy toe tomatos, salad tomatoes, etc.

  2. Hi Mark, Tomato seeds will not carry blight even if the fruit was infected. They will be safe to plant.

Leave a Comment

Your email address will not be published. Required fields are marked *

101 ways to living greener

Get "101 Ways to Living Greener"


Download free eBook with advice from experts

Scroll to Top