Thanks for the information I will write down the recipe
Tomato Blight (Identification, Prevention and Treatment)
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As an organic gardener, I often feel like I’m at a disadvantage when it comes to dealing with plant diseases like tomato blight. It’s frustrating to watch my tomato plants suffer, often being the first to show signs of trouble. This challenging condition doesn’t limit itself to tomatoes; it also impacts my zucchini, cucumbers, pumpkins, squash, melons, potatoes, and even beans!
In this article, I’ll share how to recognize, prevent, and treat tomato blight effectively. This way, my garden can stay filled with healthy plants and productive tomatoes.
Knowing how to troubleshoot issues in your garden is going to go a long way in preventing them in the first place. Knowing what tomato plant leaf curl means, or how to treat blossom end rot is a great place to start.
From there, you'll want to check out our guide to understanding tomatoes and learn how to grow healthy, organic tomatoes. You should probably also know how to pick the right seeds for your location to maximize success.
Tomato blight is a set of diseases that harm tomato plants. These diseases come from fungi, bacteria, and the environment. Knowing about tomato blight helps me grow healthy tomatoes. It lets me manage my garden and fight off diseases early.
Learning about blight can help us spot problems early, meaning we can act fast to prevent further disease. Understanding the disease's life cycle helps us predict when it might strike. Keeping plants healthy is also key as they’re less susceptible to the disease.
Understanding tomato blight helps me protect my plants from these diseases. Each part of learning about blight improves my garden and plant health. With the right knowledge and action, I can beat the challenges of blight.
Knowing about tomato blight is key to managing diseases. There are three main types: early blight, late blight and Septoria blight. Each type has its own signs and effects on plants.
Early blight is a common disease affecting plants, particularly those in the nightshade family, such as potatoes and tomatoes. It's caused by a soil-borne fungus called Alternaria solani. The name "early" does not imply that the disease occurs only early in the growing season, but it does most commonly occur early in the season.
Symptoms of early blight usually start appearing on the lower, older leaves as small brown spots. These spots enlarge, often forming a pattern of concentric rings giving a "bull's-eye" appearance. The surrounding leaf area may turn yellow. If left uncontrolled, it can cause significant defoliation, usually starting at the base of the plant and moving upwards.
Early blight can also affect the fruits of the plant. On tomatoes, dark, sunken, leathery spots can form, usually (but not always) at the point where the fruit is attached to the plant.
Late blight is a serious and devastating plant disease caused by the pathogenic water mold Phytophthora infestans. It's most infamous for causing the Irish Potato Famine in the 1840s, but it also affects other plants in the nightshade family, such as tomatoes, peppers, and eggplants.
This pathogen prefers cool, damp, and humid conditions and can spread rapidly, especially in these environments. It is one of the few plant pathogens that can produce spores both asexually and sexually, leading to great genetic diversity and adaptability.
Symptoms of late blight typically appear later in the growing season. Initial symptoms include irregularly shaped dark spots on leaves, often surrounded by a pale "halo". As the disease progresses, it may cause the entire plant to wilt and die.
It can also cause dark, firm lesions on tubers and fruits. The fruit of plants affected with late blight should not be eaten.
Septoria leaf spot, also known as Septoria blight, is a common fungal disease that primarily affects tomatoes but can also occur on other plants. It is caused by the fungus Septoria lycopersici.
Septoria leaf spot usually appears on the lower leaves after the first fruit sets. The disease begins as small, water-soaked spots. These spots darken and enlarge to form circular or angular grey or tan areas that may be up to 1/4 inch in diameter. The center of these spots later turn white and tiny black specks, which are the fruiting bodies of the fungus, can often be seen in the white centers.
This disease does not typically affect the fruit directly, but by defoliating the plant, it can lead to sunscald on the fruit. Also, heavily defoliated plants will produce fewer, smaller fruit.
Type of Blight |
Causing Agent |
Key Symptoms |
Impact on Plants |
Early Blight |
Alternaria solani |
Dark brown spots with concentric rings, yellowing leaves |
Early leaf drop, reduced yield |
Late Blight |
Phytophthora infestans |
Water-soaked lesions, mushy appearance on leaves and fruits |
Rapid plant decline, potential crop loss |
Septoria Blight |
Septoria lycopersici |
Affects the leaves, primarily, with dark circular or angular grey or tan areas. |
Defoliates the plant, leading to sunscald on the fruit. |
Early blight, caused by the fungus Alternaria solani, is a big threat to tomato plants. This fungus thrives under certain conditions. It's important to know what causes early blight to manage it well.
The following environmental factors can greatly increase the risk of early blight. By noticing and changing these conditions, you can lower the disease risk in your garden.
Cause |
Description |
Impact on Plants |
Warm, Wet Conditions |
High humidity and temperatures between 75-86°F create optimal conditions for fungus growth. |
Facilitates rapid spread of early blight. |
Moisture on Leaves |
Water left on leaves overnight encourages fungal spores to germinate. |
Increases the risk of infection. |
Overcrowding |
Plants that are too close reduce airflow, trapping moisture. |
Heightens chance of disease outbreak. |
Tomato Plant Stress |
Water stress and nutrient shortages weaken plants, making them susceptible to infection. |
Increases vulnerability to early blight. |
Late blight is a major threat to tomato plants, caused by Phytophthora infestans. This pathogen spreads quickly and can destroy crops. Knowing what causes late blight helps us fight it better.
Key causes include:
Knowing how late blight works helps us find ways to stop it.
Stage of Infection |
Symptoms |
Impact on Plant |
Initial Infection |
Water-soaked lesions on leaves |
Leaves begin to wilt and decline |
Advanced Stage |
Dark brown, decaying spots |
Overall plant health deteriorates |
Fruit Infection |
Circular, dark spots on tomatoes |
Fruit becomes inedible |
It's key to spot tomato blight symptoms early to keep my plants healthy. Catching it early means I can act fast and reduce damage. Knowing the signs of early and late blight helps my tomatoes grow well.
Looking for early blight signs, I check the lower leaves of my tomatoes. Early blight starts with dark brown or black spots with a yellow ring around them. These spots can make leaves dry up and fall off, weakening the plant and spreading disease.
Late blight signs are more serious. They show up as light brown, wet spots that grow fast. If ignored, they can destroy the whole plant. Spotting these signs early can save my tomatoes and keep my garden healthy.
Choosing the right tomato variety is key to keeping them healthy. I look for blight-resistant tomato varieties that fight off diseases. These include ‘Defiant’ and ‘Brandywine’ which are great against early and late blight.
Tomato Variety |
Resistance Type |
Characteristics |
Defiant |
Early & Late Blight |
Medium-sized fruit, disease-resistant, great flavor |
Early Blight |
Large fruits, rich taste, traditional heirloom |
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Celebrity |
Early Blight |
Compact growth, versatile use, reliable producer |
Early & Late Blight |
Sweet cherry tomatoes, excellent for snacking |
Environmental control measures can greatly lower the risk of blight. Here’s what I focus on:
Knowing exactly how to treat infected tomato plants can be confusing with so much varying information out there. But rest assured, it's actually very easy to treat any form of blight, as long as you catch it early and treat it until it's gone.
Start by cutting off any infected leaves. This stops the disease from spreading and lets healthier parts grow. Keeping a close watch on your plants helps you catch and remove sick parts quickly.
Using organic fungicides is also important. These products help fight off infections. Applying them regularly during the growing season helps protect your plants from early blight, late blight, Septoria blight and even powdery mildew.
Though you can use organic fungicides like neem oil or potassium bicarbonate, or even copper-based fungicides, they’re expensive. I have used a solution made from ingredients you likely already have in your kitchen for years, and it’s always done the trick.
Baking soda works by creating an alkaline environment on the leaf, and fungi cannot colonize the surface of the leaf since they need a neutral pH (around 7.0) to survive and thrive.
This spray of water and baking soda will change the leaf's pH from around 7.0 to around 8.0. This change is enough to kill and prevent all blight spores!
Pro Tip: Begin with 3 tablespoons of baking soda and apply once weekly for three weeks. If fungus is still growing or spreading, increase to 3 ½ Tablespoons and continue spraying once per week for an additional three weeks.
WARNING: Spray in the morning or evening, as spraying in the heat of the day can harm your leaves. It’s ideal to spray in the early morning to avoid wet leaves sitting overnight.
Tomato blight shows up in different ways, depending on the type. Early blight causes dark brown spots with rings on lower leaves, which may die off. Late blight leads to water-soaked lesions that turn light brown, potentially killing the plant.
To stop tomato blight, plant tomatoes with enough space for air to move around them. Rotate crops yearly and avoid watering overhead to keep leaves dry. Good sunlight and managing humidity are also key to prevention.
Yes, some tomatoes like ‘Defiant’ and ‘Brandywine’ are made to fight early and late blight. Choosing these can lower the chance of infection.
If tomatoes show any signs of blight, cut off and discard any infected leaves to stop the disease from spreading. Use the baking soda spray weekly, watch plants closely and act fast at first signs of disease.
Blight loves heavy dew and cool, wet weather. These create high humidity that helps fungi grow.
Early blight, from Alternaria solani, hits older leaves with dark spots and a yellow ring. Late blight, from Phytophthora infestans, causes fast plant decline and is known for its severe effects, like the Irish Potato Famine.
Spotting tomato blight early means checking for leaf spots, wilting, and plant health. Looking for dark spots or water-soaked lesions helps to catch problems early.
Too much moisture from dew or bad watering helps fungal diseases like early and late blight grow. Keeping leaves dry and ensuring good airflow can reduce these risks.
Comments
Thanks for the information I will write down the recipe
Thank you. Now I know what to do.
Can you tell me why my Yukon gold potato plants are producing tomato looking fruit on them
Thank you for this very informative post . I will keep this recipe handy in case I grow these plants. (I would love to grow veggies!)
Thanks for info & recipe!