by Matt Gibson
About Early Blight
Early blight is a common tomato disease that is caused by the fungus Alternaria solani. Affecting nearly all parts of the tomato plant, including the stems, leaves and fruit, early blight is very common in areas with warm, moist weather conditions. Despite its misleading name, early blight can rear its head at any time during the growing season, causing unsightly damage to the leaves, stems, and eventually the fruit of your beloved tomato plants.
It is important to note that early blight and late blight are completely different diseases that are caused by different fungal pathogens. The main difference between the two is that early blight is easier to treat and prevent if signs of infection are spotted early enough. So, to help you remember the difference, if you catch early blight early enough, you may be able to revive your tomato plant, but if you catch late blight early, you are still too late to do anything about it.
Causes And Symptoms of Early Blight
Tomatoes affected by early blight will have oval-shaped irregular brown or black spots on older leaves which become noticeable ten days after the infection begins. These spots will develop multiple rings, creating a target-like design as the disease progresses further. Eventually, if no action is taken, the spots begin to yellow and the leaves start to drop off the plant. As the leaves fall away, the unprotected fruit is left to bake in full sunlight, causing it to scald and ruin.
Early blight also directly affects the fruit of the tomato plant, causing dark, sunken, leathery spots to occur on the ends of the plant’s stems. The rot then goes down into the fruit of the tomato and eventually causes the fruit to drop from the plant. The disease overwinters on plant debris and grows strong in warm, moist weather conditions. Using control spray is very important to rid the garden area of the disease entirely, as the disease will often enter through a cut, bruise, or wounded area of a healthy tomato and infect the entire plant.
Treatment and Control of Early Blight
Follow a good fungicide regimen using a fungicide recommended specifically for early blight. Plant only disease-resistant varieties of tomatoes (such as Mountain Fresh, Mountain Supreme and Plum Daddy cultivars) after treating the beds with fungicide and removing all old plant debris completely, following fungicide instructions carefully.
The best way to keep early blight out of your garden is to practice control methods. Early blight is a soil borne fungus that occurs when the leaves of the tomato plant get too wet and get soil particles on the underside of the leaves. In order to keep the leaves from getting dirty, there are practices that you can try that will keep the leaves from touching the ground. Cover the soil with at least six inches of mulch during the growing season, putting a layer of protection in place, so that the leaves don’t touch the soil directly.
Remove old plant debris completely and discard of it in the garbage. Do not compost affected plants or you will most likely be reintroducing the disease to your soil down the road. Rotate your crops often. Carefully space out your plants to promote good air circulation to help your plants dry out after a rain or watering.
Commonly Asked Questions About Early Blight
Can you eat tomatoes with early blight?
Yes, tomatoes with early blight can often be salvaged and eaten with no ill consequences. Blight is a localized disease, which means that it happens in a particular location within the plant. If the blight is not directly on the fruit, then the fruit shouldn’t be affected by the blight, other than slightly stunted growth, the fruit should be edible and can be harvested and used normally. Blight can affect the fruit of the plant, in which case, the damage of the blight will be evident, the fruit will be deemed as unsalvageable, and discarded.
What is early blight on tomato plants?
Early blight is a fungal infection that overwinters in the soil and attacks tomato plants at the stem, leaves, or even fruit. The first symptoms appear as concentric rings which form a bullseye pattern on the older, lower leaves. The brown circular spots move outward and spread over the surface of the leaf, turning the leaf yellow, and causing it to wilt and die. Eventually the stem, fruit, and upper part of the plant will get infected.
Does tomato blight stay in the soil?
Yes, tomato blight stays in the soil and overwinters, ready to strike again the following growing season. Blight fungus can live in the soil for over a year and thrives in warm, moist conditions.
Does baking soda kill blight?
Baking soda is an effective natural treatment for blight fungus. It has fungicidal properties and can stop or significantly reduce the growth and development of early and late blight disease. Baking soda spray can be made by mixing a teaspoon of baking soda with a quart of warm water and just a drop or two of dish soap to help the mixture stick to the tomato plant.
Does neem oil kill tomato blight?
Neem oil is a good treatment for powdery mildew and many other fungal infections, but it doesn’t do much against blight.
How do you stop tomato blight?
There are many different ways to stop tomato blight. Control methods are the best way to prevent tomato blight from occurring. These methods include rotating your crops, spacing out plants to increase air circulation, add a six inch layer of mulch during the growing season to keep leaves from touching the soil. Try to keep leaves dry during irrigation, watering the soil directly, and from a low angle to minimize splashing. Once blight has infected your plants, remove affected parts of the plant with disinfected shears, cleaning in between each cut. Dispose of all infected parts. Stop the spread of tomato blight with organic treatments such as copper (preferred), sulphur, or bacterial fungicide, or potassium bicarbonate.
How do you treat early tomato blight?
Prune away diseased parts of plants, disinfecting your shears after each cut you make using a disinfectant made from one part bleach to four parts water. Stake plants to improve air circulation.
Keep the soil under plants free of garden debris and add a layer of organic compost or mulch to keep fungal spores from splashing up onto the plant. Use drip irrigation or soaker hoses, or water from a low angle to help keep foliage dry and water the soil directly.
Copper-based fungicides are the most effective against blight. Follow fungicide application directions correctly. Remove all garden debris after harvesting and practice crop rotation regularly. Burn or discard all plant parts in the trash. Do not compost.
What is the difference between early and late blight?
Late blight is caused by Phytophthora infestans. Early blight is caused by Alternaria solani. P. infestans is much more aggressive and spreads much faster than A. solani, killing all infected material while causing dark, watery splotches to form.
Early blight, or A. solani, can be reversed if spotted early enough in the infestation, saving the plant by removing and disposing of infected parts of the plant and treating with a copper fungicide. Late blight, or P. infestans infected plants cannot be saved, and should simply be discarded or burned once the presence of infection is noticed.
There are many control methods that can be used to prevent future attacks from early blight, while the only things you can do to fight against late blight is to destroy any infected plants immediately, practice crop rotation, and grow resistant varieties.
What tomatoes are resistant to blight?
- Juliet Tomato – The Juliet variety produces a red elongated cherry tomato that is resistant to both early and late blight.
- Old Brooks Tomato – Old Brooks is an heirloom red globe tomato resistant to both early and late blight.
- Ferline Tomato – Ferline tomatoes range in color from green to yellow, orange, and red in five ounce globes. They are highly resistant to blight.
- Legend Tomato – The Legend is a giant red beefsteak tomato variety which is resistant to both early and late blight, but with an exceptionally strong resistance to late blight.
- Golden Sweet Tomato – The Golden Sweet variety is a deep yellow grape tomato that is resistant to late blight, but not early blight.
- Mountain Supreme Tomato – This red globe cultivar is blight resistant.
- Mountain Fresh Plus Tomato – This red globe cultivar is early blight resistant, but not late blight resistant.
- Tommy Toe Tomato – Tommy Toe is a red cherry heirloom variety that is resistant to early blight.
- Fantasio Tomato – The Fantasio tomato is late blight resistant and produces eight ounce red globes.
- Manalucie Tomato – An early blight resistant cultivar, Manalucie has red globe tomatoes.
- Manyel Tomato – Tangy, citrusy, big yellow globes adorn the Manyel tomato plant, which is blight resistant.
- Matt’s Wild Cherry Tomato – Matt’s Wild Cherry is resistant to early blight, and produces ½ inch red cherry tomatoes.
What are the most disease resistant tomatoes?
‘Defiant’ and ‘Iron Lady,’ are great picks for red slicers. ‘Brandy Boy’ and ‘Pink Brandymaster,’ are soil borne disease resistant pink slicers. ‘Marnero’ is a choice purple slicer, and ‘Mountain Magic’ is perfect for disease resistant grape tomatoes.
Is tomato blight harmful to humans?
There is no documented incidents of harm from eating blight-infected fruit, but that does not mean that infected fruit is not holding bacteria and other organisms that could cause you to get sick. As a general rule, if a tomato looks infected, toss it out, or cut around the infected part and discard any infected looking areas of the tomato.
What is the cause of tomato blight?
Tomato blight is caused by the fungus Alternaria solani. In warm, moist weather conditions, fungus spores attach themselves to the underside of low-lying leaves of the tomato plant.
What do you do with soil after tomato blight?
First, remove all vegetation from the tomato bed and other affected garden areas immediately after harvest at the end of the growing season, removing all tomato, potato, or nightshade plants from the area entirely. Dig into the soil deeply and uproot the entire plants, removing every bit, even broken pieces of stem and root. Place all vegetation trash into plastic bags. Seal the bags and discard them immediately.
Till the garden beds vigorously in late autumn. Disturbing the soil a few times during the fall and winter will keep blight spores from establishing habitats in your soil and overwintering. Inspect the garden in the spring before treating the soil or sowing new plants. Remove any additional vegetation that may be infected with blight. Look for nightshade weed, and any stray tomato plants or potato vines that may have sprouted up in the area. Pull up and discard anything you find.
Then, spread four inch layers each of compost and sand, working them into the top six to nine inches of soil in the garden beds. This amendment will improve drainage and help the soil retain heat, which will lower the chances of a soil environment suitable for fungal growth. Cover garden beds with plastic mulch to heat the soil, lower humidity, and kill any spores still in the soil. Cover pathways with a layer of large mulch, such as wood chips. If you are not using white plastic on the beds, mulch them also. The mulch will lower the probability of fungal spores reaching the leaves of your plants through splashing mud after irrigation.
Want to learn more about tomato early blight?
StackExchange covers Is it Safe to Eat Tomatoes Affected by Early Blight?
StackExchange covers Tomatoes: Difference Between Early Blight and Late Blight
GardenTech covers How to Identify, Control and Prevent Blight on Your Tomatoes
SFGate Homeguides covers How to Repair Soil with Tomato Blight
Planet Natural Research Center covers Early Blight
the Spruce covers Early Blight on Tomatoes
Tomato Dirt covers Tomato Blight
Tomato Dirt covers Blight Resistance Tomato Varieties