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Tomato Blight: Identification, Prevention, and Treatment
Tomato blight can be disastrous when it hits your garden. Fortunately, with a few tips you’re likely to prevent this disease and, in some cases, cure affected plants. Here’s all you need to know about the three most commonly known strains of tomato blight:
What Causes Tomato Blight?
What is tomato blight? Tomato blight is caused by different types of fungi. The spores can travel via wind, water, insects, and/or soil. Warm and wet conditions encourage their growth.
There are 3 main types of tomato blight, and unfortunately one or more can be present on your tomatoes at the same time.
Early blight (Alternaria solani) can appear throughout the growing season. It generally affects the fruits, leaves, and stems and causes the plants to become weak and produce less. It can potentially kill tomatoes if severe enough.
Late blight (Phytophthora infestans) is extremely deadly and can turn all your fruits (and potatoes too) into a shriveled mess in a matter of days. As you’d expect from the name, it typically appears later in the growth cycle, but can be present on seedlings as well. It spreads through wind and soil and can overwinter in potato tubers.
Septoria Leaf Spot
Septoria leaf spot (Septoria lycopersici) is another common fungal disease grouped under tomato blight. It typically doesn’t kill your tomatoes, but it can be an eyesore and harm production if not treated.
Tomato Blight Pictures & Identification
What does tomato blight look like? Usually early blight starts with brownish-grey rings appearing on the leaves and stem.
Late blight generally starts with browning leaves that quickly die, along with brown lesions and white mildew on the stems and fruits.
Tomatoes affected by septoria leaf spot will have small round brown or black spots with lighter centers all over the leaves, which can have small filaments coming out of them.
The following video gives helpful tips for identifying each type of tomato blight (along with a few other common tomato diseases!)
How to Treat Tomato Blight
For prevention or early blight cases, you can try a homemade baking soda tomato blight treatment. Combine a tablespoon of baking soda, a teaspoon of vegetable oil, a dash of soap, and a gallon of water, then spray the plants on a regular basis.
No matter what you use, if you find early blight or septoria leaf spot, you should at least prune off the affected areas if they’re small enough. Burn or bury the clippings far away from your garden, and sanitize your pruning shears and any other tools you used.
Plants with late blight should be fully disposed of as outlined in the following section:
How to Get Rid of Tomato Blight
Depending on the type of blight you have and its severity, you may have to immediately dispose of the plant and cut your losses. Late blight can’t be treated, so pull up any plants afflicted by late blight and burn or bury them far away from your garden. You can remove any untouched tomatoes before disposing of the rest of the plant, since they are still edible if used quickly.
Second, make sure you thoroughly disinfect anything that came into contact with the tomatoes, including stakes, shovels and other tools, greenhouse materials, and more.
Tomato Blight Soil Treatment
There are no known soil treatments for late blight aside from time and freezing temperatures. However, early blight and septoria leaf spot can both potentially be treated using soil solarization during the summer. Also known as tarping, this method heats the soil, killing early blight and septoria leaf spot fungi along with most other living organisms. Keep in mind that it does take at least 6 weeks and can only be done in late spring and summer, but by the following year you should be able to plant tomatoes again.
How to Prevent Tomato Blight
You can take a few measures to avoid tomato blight.
First, consider picking a blight resistant variety. While they may still have problems if the conditions are right, resistant varieties will often last longer than traditional ones. Mountain Magic and Celebrity Hybrid are both good options.
If possible, try growing your tomato plants indoors, either in greenhouses or even in your home. Keeping them inside lessens their chance of picking up diseases, since they’re exposed to fewer outside air and soil particles and their moisture and temperature can be controlled.
If you can’t plant indoors, plant your tomatoes in areas where tomatoes, peppers, eggplants, and potatoes haven’t been planted for at least four years. Be careful to avoid using any soil or compost that might have held plants touched by blight. Using good crop rotation principles will help.
Pick your tomato companion plants carefully and avoid plants like potatoes, which also suffer from blight.
Make sure your tomato plants are correctly spaced so they get plenty of airflow and stay dry.
Consider staking the plants and pruning them regularly to make sure they continue to get plenty of air. Prune the bottom leaves when the plant is fruiting so they won’t touch the ground.
You should also make sure you’re watering them correctly. Water at the base of the plant to keep excess water off the leaves, and try to keep the water from splattering soil everywhere, since this can stir up fungi. You can mulch directly around the base to further help with soil splash.
Most important of all, keep an eye on your tomatoes. If you notice any signs of blight, identify the type you have and treat your tomatoes as quickly as possible.
Enjoy Your Tomatoes
You should now know how to prevent tomato blight, along with the signs of blight to watch for so you can perform one of the treatment options early on.