Tomato Early Blight Disease – Causes, Symptoms and Treatment
This year, my tomatoes were struck by early blight.
I never had this problem with my tomatoes before, so it was an issue I didn’t know how to handle.
At the time I was able to identify the source of the problem, it was too late to treat the plants with an antifungal.
I didn’t know the name of the disease so I started to seek for an answer using Google.
I first looked for images that resembled the characteristics of the affected tomatoes. At first, I thought I’m facing with the blossom end rot, but the tomato fruit didn’t have the rot at the bottom, but to the stem that kept the tomato fruit attached to the plant.
Finally, I saw a photo that matched exactly the symptoms my tomatoes had and I found out that my veggies are facing the tomato a disease called “early blight”.
After the research on what’s causing this disease, which are the initial symptoms and the treatment, I decided to write this tiny guide.
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What is Early Blight?
Early Blight is a plant disease caused by a fungal pathogen called Alternaria Solani.
Alternaria Solani is known to affect in particular the tomato and potato plants.
There are two forms of blight diseases:
- Early blight
- Late blight
Between the two, late blight is the most devastating and can rapidly destroy your entire tomato or potato plantation.
The late blight is caused by Phytophthora infestans, a microorganism which prefer moist and cool environments.
It’s pretty easy to identify if your plants have been affected by early or late blight.
The evolution of late blight is much quicker than the one of early blight. When a tomato is affected by late blight, the entire plant along with its fruits can be destroyed in only a few days from the first symptoms.
In the initial stages, early blight will cause dark brown (or black) spots on the leaves of the plants (starting from the leaves at the bottom of the plants).
After some time, the affected leaves will turn yellow and either dry up or fall off the plant.
Later on, there will appear lesions on the fruit. More exactly, the tomato fruit will start to turn black at the lower main stem (the green tail that holds the tomato fruit attached to the plant).
Eventually, the sick tomato fruit will fall on the ground.
If the tomato fruit managed to reach its maturity and was only affected in a small manner, you can cut off the affected part and consume the rest.
Plant diseases don’t affect people and the tomato fruits that only present an initial stage of the disease will only present a tiny black spot at the stem that can easily be removed.
The infections with late blight usually produce larger dark brown lesions (look like rot) on a random area of the tomato fruit and can rapidly extend to the whole surface of the fruit, destroying it completely.Most of the time the tomato fruits affected by late blight get a bad smell and become inedible.
Early Blight Treatment
While you can’t do many things to save your tomatoes once they were affected by late blight, there are a few things you can do to treat early blight.
Utilize fungicide at the first signs of disease
Once you’ve seen the first signs of early blight affecting your plants, one of the best solutions is to apply a fungicide treatment.
Since the disease is caused by a fungus, a fungicide is one of the most efficient solutions.
Here are my top 5 most effective fungicides for tomatoes.
Remove affected leaves
You need to closely watch for the first signs of early blight, which are the appearance of brown dark spots on the leaves at the bottom of the tomato plant.
Remove the affected leaves (you can also remove any leaves that are very close or hanging on the soil) and throw them away or burn them once they dry out.
Do not use those for your compost (here’s my composting guide) since you risk contaminating your next generation of tomatoes or potatoes when you use the compost.
I found a supposed organic remedy for early blight on Jeff Bernhard’s YouTube channel.
Even though I haven’t tested yet, I’m going to list the ingredients here.
You’ll first need a spray bottle. If you don’t have one already, you can buy one from Amazon for a few dollars.
- 1 gallon of water
- 3 table spoons of baking soda
- 1 table spoon of vegetable oil
- 3-4 drops of organic dish soap
Mix all the ingredients together and spray the solution on the affected tomato or potato plants.
According to Jeff, this is going to create a solution that should prevent the fungus spores from being able to survive on the leaves or on the stems of the plants by increasing the pH level.
You can spray the finished solution early in the morning or late in the evening.
Early Blight Prevention
The fungus that causes early blight is favored by warm temperatures and high humidity.
Below are several tips that should lessen the chances of the occurrence of this disease.
– Leave enough space between the plants
Overcrowded plants will create a favorable environment for Alternaria solani since will maintain a lastingly high level of moisture.
– Rotate crops
Alternaria solani can remain in the soil even after you have removed your affected plants. If the fungus has the proper conditions, it can remain dormant and affect your next culture.
If you had problems with early blight in the past, the best way to prevent the recurrence of this disease is to rotate the crops.
Keep in mind though that the early blight can also affect potatoes. Hence, don’t grow the potatoes in the same area where your diseased tomatoes were planted and vice-versa.
– Only use certified seeds
This pathogen can also infest the tomato seeds. Therefore, make sure you don’t use seeds obtained from unhealthy fruits.
Make sure you buy seeds or tomato seedlings only from certified and trusted sellers.
– Do not irrigate in excess and avoid splashing the plants with water
Early blight cannot infect a perfectly dry leaf. Even though it’s impossible to keep the leaves of your plants perfectly dry, avoid as much as possible splashing the plants directly.
– Apply a layer of mulch over the surface of the soil
The fungus is usually found in the soil.
Besides preventing the weeds from invading your garden, the mulch can prevent the occurrence of early blight. Read my post about the best mulches for vegetable gardens.
When you sprinkle the tomatoes or when it’s raining and pieces of mud splatter the leaves of the plant, the fungus can contaminate it. The mulch will prevent that from happening since it forms a protective layer between the plant and the surface of the soil.