Whether planting outside or in a greenhouse, tomatoes can be affected by a number of diseases. This list includes several common tomato diseases and natural solutions to them.
Check over the symptoms carefully, since some ailments may look similar, particularly in the early stages. If you’ve had any problems like these in the past, use this guide to identify and treat them naturally, especially for heirloom tomato varieties.
As mentioned earlier, you’ll find a lot of information on diseases for tomato plants in this article. Be sure to pin or bookmark it for future reference.
1. Leaf Curl
Mature plants will have their leaves curl from the outside to the centers.
Environmental stress causes tomato leaf curl — high temperatures, too much water, over-pruning, lack of water, or damage to roots.
Thankfully, it doesn’t affect the taste of the fruits. You can avoid it by making sure your soil drains well. Additionally, avoid the temptation to over-prune and give adequate water and heat supply.
2. Septoria Leaf Spot
Septoria leaf spot is caused by a fungus. It characterizes circular spots that turn brown with gray centers before drying.
A severe infection will kill the whole leaf. Over time, the leaves will turn yellow and eventually dry out and fall off. A decline in leaves will weaken the plant causing it to stop producing fruits.
Removing infected debris is vital. Also, practice crop rotation and reduce overhead watering.
3. Leaf Mold
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Another fungal disease, leaf mold shows up as yellow spots on the upper side of leaves. Also, underneath these spots are purple or olive-green patches of mold.
Infected leaves will turn yellow and fall off. Wind can spread the mold, and high humidity and temperatures encourage mold growth. Infections can be severe in greenhouses and the fungus can also affect blossoms, fruits, and stems.
Consider rotating crops with other vegetables. Stake and prune plants for better air circulation and avoid wetting the leaves.
BioSafe is also an excellent preventive and curative organic fungicide against leaf mold fungus on tomato plants and other tomato leaf diseases.
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Anthracnose is an easy one to spot. You will find dark, sunken in spots that will be mushy. If you cut open the fruit, the area under the spot will look rotten.
This tomato fruit disease is caused by the fungus Colletotrichum coccodes. It spreads by overhead watering that splashes the fungus from infected soil or other plants onto the plants.
You can prevent it by using watering that drips onto the roots. Also, harvest early since it doesn’t tend to affect tomatoes early in the ripening process.
Also, plant your garden in a sunny area and keep it weed-free. Cage or stake plants to improve air circulation and prevent it.
BioSafe can also help.
5. Fusarium Wilt
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With Fusarium wilt disease of tomato, your plant will start to wilt and turn yellow. It might only affect half of the plant at first. However, it will quickly spread to the whole plant and kill it.
It’s caused by the fungus Fusarium oxysporum f. sp. lycopersici and can survive for many years in the soil .
This nasty tomato fungus is best prevented by crop rotation and using an organic bio-fungicide such as Mycostop.
6. Verticillium Wilt
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Verticillium wilt is caused by Verticillium dahliae andVerticillium albo-atrum . These soil-borne fungi attack the root and prevent the flow of nutrients and water up to the leaves.
Older leaves on plants infected with the disease will turn yellow at the leaf margins before turning brown. These tomato fungi develop rapidly in cool weather.
However, it isn’t easy to deal with. The most effective options are crop rotation, getting rid of infected crops, and keeping the garden weed-free.
7. Early Blight
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Early blight of tomato is characterized by black spots surrounded by wide areas of yellow spots on the leaves. The leaves will have a characteristic pattern described as an oyster shell or bullseye.
To prevent it, avoid wetting leaves. Warm, wet weather increases the chances of infection and spreads it faster.
As it is caused by a fungus, if you’ve had similar issues with your tomatoes or related plants like potatoes or peppers, you can have it again.
Crop rotation, pruning, Cueva, and drip irrigation can help deal with this disease.
8. Late Blight
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Late blight of tomato is characterized by dark lesions that appear water-soaked on the leaves that eventually turn powdery white.
Fruit lesions are large greenish-brown patches with a greasy appearance. It tends to appear during cool, wet weather and can affect any part of the plant.
Keeping your plants away from other relatives like potatoes, peppers, and eggplants can help. Also, keep foliage fry and plant garden in a sunny area.
9. Mosaic Virus
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With the tomato mosaic virus, you will notice dappled leaves with yellowing and new growth will be twisty or malformed. Fruits may also appear unevenly ripe.
Insects such as aphids can spread it. To effectively control the spread, destroy plants as soon as the disease appears. Also, be sure to wash your hands thoroughly after touching an infected plant and sterilize any equipment.
ZeroTol, a 3-in-1 organic fungicide, algaecide, and bactericide that can also reduce the spread of the pathogen.
10. Blossom Drop
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Blossom drop is fairly self-explanatory — blossoms will grow on your plant but will drop off before maturing.
Temperature fluctuations, too little water, insect damage, improper nitrogen levels, or lack of pollination can cause it.
You can’t change the weather, but you can have your soil tested, water properly, and plant plants that draw pollinators to your garden.
Be sure you water deeply as well and use high nitrogen fertilizers such as alfalfa meal, bat guano, fish meal, and seaweed.
11. Blossom End Rot
Your plant will look healthy, but the fruits will have a dark patch on the end of the fruit that widens and deepens over time. This is a sign of calcium deficiency in your plants.
Get a soil test kit at your local garden store. If calcium is low, you can either add crushed eggshells to your compost or apply rock mineral compounds to raise calcium.
Check your local organic gardening center for advice. Also, be sure to water evenly to help prevent issues.
Additionally, apply organic fertilizers or compost regularly throughout the growing season, since the plants need a lot of nutrients to grow.
12. Damping Off
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Damping off is a fungal disease that can cause a sudden collapse of seedlings or seeds that fail to germinate.
The stem base generally looks cut off or pinched. Seedlings will also wilt and die soon after emerging from the soil.
To help prevent it, plant seeds when soil temperatures are ideal. Also, pre-soak them to help speed germination.
If you’re using a potting mix, be sure to use sterile potting soil that has undergone heat processing. Also, ensure your soil dries out between waterings, and avoid starting seeds in soil that is rich in nitrogen.
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Plants affected by sunscald will look healthy, and fruit develops normally. However, as the fruit ripens, yellow or white patches appear and give it an unpleasant look. Later, mold may grow in the white spots and cause rotting.
Continued sun exposure causes sunscald. The best thing to do is avoid over-pruning. Also, consider using a cage over stakes since they tend to provide more sun protection.
Water on the plants and fruit magnifying the sun can also cause damage. Leave plenty of foliage to protect your fruit.
14. Bacterial Speck
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You can find Bacterial Speck in many parts of the plant. Affected areas will have small black or brown necrotic spots surrounded by a yellow border.
There is no cure for the disease; however, drip systems are a good solution to prevent many tomato plant diseases.
An organic copper fungicide such as Cueva may also be applied at the first sign of symptoms.
15. Bacterial Spot
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The bacterial spot appears as dark, water-soaked spots that eventually turn black and drop out, leaving holes in the leaves. Also, black specks become scab-like spots on the fruit.
16. Bacterial Canker
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Bacterial canker is easily detected by leaves that wilt and die, drying while still attached to the stem. The leaves and stem may also have dark patches, with sunken veins. Additionally, the fruits will have yellow dots as they ripen.
Prevention involves crop rotation and keeping the garden weed-free. Also, remove infected plants immediately and don’t compost them since that can spread the infection.
17. Spotted Wilt Virus
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Leaves will show yellow speckling and growing tips may die. Besides, the fruits may look malformed, with green, red, and yellow spots and blotches.
Tomato spotted wilt virus is caused by thrips — tiny harmful flying insects. Check new plants carefully and practice good pest control to help get rid of thrips.
Elimination of infected plants is also effective in controlling it. Clean cultivation is very important as well.
18. Fruit Crack
Fruit cracks are exactly what it says, cracks appearing in the fruit. It is caused by rapid changes in moisture levels — getting heavy rains or excessive watering after a dry spell. The tomatoes will take up too much water and eventually crack.
The best solution is to keep up on watering, especially during drought, so they don’t go into shock with rainwater. However, this generally isn’t too much to worry about. The fruits are still edible so long as you cut off the cracked areas.
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Catfacing results in deformed-looking fruits. The exact cause is unknown; however, the condition mostly occurs in cool weather. Pruning and high nitrogen levels can also lead to the disorder.
To help prevent this condition, monitor temperature levels, avoid excess pruning and cut down on high-nitrogen fertilizers.
20. Powdery Mildew
White spots on tomato leaves represent powdery mildew. It can also be characterized by yellow spots covered with a gray powder on the surface of the spots.
The leaves will die but typically stay attached to the stem. Also, humidity coupled with dry conditions makes it worse.
21. Pith Necrosis
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Pith necrosis is caused by the bacterium Pseudomonas corrugata .
It might not always be visible externally, but it causes the pith of the stem to turn brown and eventually die, leaving hollow spaces that can cause collapse.
This is more common in greenhouses; however, you can also find it in field-grown tomatoes and other areas where conditions are humid.
The best treatment is to avoid humidity and planting during cool, wet weather. Also, excessive nitrogen can make it worse, so employ balanced fertilization. However, plants can recover if conditions improve.
22. Buckeye Rot
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Buckeye rot of tomato is caused by a fungus that leaves a brown or green stain-like spot that resembles a buckeye. It can also affect relatives like peppers and eggplant.
Avoid soil contact with the fruit to help prevent infection, avoid overwatering, and ensure your soil drains well. Also, rotate crops as well or consider raised beds or container gardening.
23. Southern Blight
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Southern blight is seen as a white fungus growing near the soil line. Plant leaves will also show signs of yellowing and wilting. Besides, fruits will look water-soaked and start to rot.
To prevent and treat this disease, keep up good crop rotation and remove infected plant debris. Applying a high-quality, cold-pressed neem oil such as Rango can also help control it.
24. Root-knot Nematodes
Root-knot nematodes are microscopic worms that live in the root of plants or the soil. You will know there is a problem when plants start showing signs of wilting, yellowing, and stunting.
Additionally, the critters produce galls and large swellings on roots.
You can either relocate the garden to an area that is free of nematodes or add parasitic nematodes to help decrease occurrences.
25. Gray Leaf Spot
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The gray leaf spot is caused by the fungus Stemphylium solani.
You’ll see small brownish-dark specks that will grow into larger necrotic areas that crack open, leaving a shot hole type appearance. In addition, a grayish-brown color will appear as the spots get larger.
Spots may also have a yellow halo, and severe infections can cause leaf drop, yellowing, and defoliation.
The fungus can survive on weeds in the same family, so keep up on weeding. Additionally, CEASE organic fungicide can help suppress gray leaf spots and other tomato leaf ailments.
When you’re dealing with tomato plant problems, please note that not all color changes may be due to plant diseases. You have to examine the plant carefully for patterns and color combinations.
For example, yellowing leaves may be caused by magnesium deficiency where the leaf would become yellow and wilt before falling. The deficiency of magnesium can be resolved by using Epsom salt.
Advice from your local organic gardening center can be very helpful as well. Also, good sanitation of your tools and hands can help prevent disease spread, as well as crop rotation. Lastly, be sure NOT to compost infected plants or parts so you don’t spread anything further.