Are you frustrated with the unsightly black spots on your tomatoes? These spots, also known as septoria leaf spots, can not only ruin the appearance of your tomatoes but also reduce the plant’s overall productivity. Initially, to get rid of black spots on tomatoes, some of the best ways are-
- Water at the base, avoid overhead watering.
- Prune and remove infected leaves.
- Use natural remedies, such as neem oil and garlic spray.
- Apply commercial fungicides.
- Provide adequate sunlight and ventilation.
Inside this post, we will explore the potential causes of black tomato spots as well as give you a thorough breakdown of multiple proven methods to eliminate them.
How Black Spot Formed What are the Key Causes?
The black spots on tomatoes result from a fungal infection called Septoria lycopersici. Their spores can be found in the soil and infect your tomato plants when conditions become favorable for their growth.
Excess moisture, poor ventilation, and cool temperatures are some of the most common causes that contribute to the development of this fungal infection.
The fungus thrives in dark, damp environments and can quickly spread from one plant to another if the infestation is left untreated.
If you’re an avid tomato gardener, the issue is even more severe because when spores remain in the soil after several years of planting tomatoes in one place, a persistent infection will inevitably occur.
Septoria Leaf Spots: Why Does It Be More Frequent In Tomatoes?
As you will see, septoria leaf spots are the most common cause of black spots on tomatoes.
Septoria leaf spot is a fungal disease that affects tomato plants, as well as other vegetables in the Solanaceae family, including potatoes and peppers. The fungus prefers warm temperatures with high humidity and can spread rapidly under these conditions.
And we know, tomato is one of the warm-season vegetables (70 to 85 degrees Fahrenheit) and they require a lot of moisture to grow. As a result, tomatoes are especially susceptible to this fungus when conditions become favorable for its spread.
Another reason that I already discussed is the shallow practice of crop rotation.
Symptoms and Progression of Septoria Leaf Spots
- Initial symptoms of septoria leaf spot include small, circular yellow spots on leaves.
- As the disease progresses, the spots become dark brown with grey centers (1/16 to 1/8″ in diameter)and may have a “shot-hole” appearance.
- The spots may also develop dark, pycnidia-like structures on their surface.
- As the disease spreads, leaves may yellow, wilt, and die.
- Eventually, the fungus can spread to the stems and cause defoliation and plant death.
So, How To Get Rid of Black Spot on Tomatoes?
As a gardener and agriculturist, I can assure you that it can be managed to get rid of Black Spot on Tomatoes. Here I discuss some invaluable tips that can help you control and eradicate this issue:
Seed Treatment:
Seed treatment is important in preventing the spread of black spots on tomatoes because it can help prevent the fungus from infecting the plant from the start. When seeds are treated with a fungicide, the fungicide will be absorbed by the seed and can protect the emerging seedling.
This can help prevent the fungus from spreading to the leaves and stems of the plant, which can reduce the likelihood of black spots developing.
Data from field-level research shows that using a seed treatment can increase the chances of a successful tomato crop by reducing the incidence of black spots.
One study found that using a seed treatment resulted in a 76% reduction in black spot incidence compared to untreated seeds. Another study showed that seed treatment resulted in a 64% reduction in the severity of black spots on tomato plants.
Crop Rotation:
Crop rotation is an important agricultural practice that involves growing different types of crops in a specific area over time. This practice can help prevent soil depletion and reduce the spread of pests and diseases.
By planting tomatoes in a different location each year, you can help reduce the buildup of fungal spores in the soil and prevent the disease from spreading.
Keep The Garden Clean:
If your garden contains tomato plants that have been affected by black spots, it’s important to keep the area clean and free of debris. Remove any diseased leaves and plants, and appropriately dispose of them to prevent the spores from spreading further.
It’s also important to avoid working with wet foliage, as this can cause the spores to spread more easily. Make sure to water your plants early in the morning so that the foliage has plenty of time to dry before nightfall.
Proper Fungicide Application:
In most cases, the use of chemicals is not necessary to prevent or treat black spots. However, if the problem persists, then using a fungicide may be necessary. You can start with chlorothalonil and mancozeb is labeled for homeowner use for quick and easy application.
- Chlorothalonil: If plants are interacting with wet, moist, or rainy conditions, should stop using it the day before harvesting.
- Mancozeb: Frequently used fungicide for all weather conditions. Should stop using fungicides at least 5 days before harvesting.
- Antracol: When a circular leaf spot with a large yellow halo (6-12mm) is surrounded, elongated stem lesions and sunken dark brown to black circles on the fruits are visible, these marks can cause fruit rotting over time.
Furthermore, you must first use natural remedies after seeing the symptoms of black spots on your tomatoes. Some natural remedies are neem oil, garlic oil spray, and sulfur spray will be organic and cost-effective solutions.
They may be too little too late after the fungus has already taken hold, but they might help prevent future outbreaks of black spots.
Proper Irrigation and spacing
To ensure a bumper crop of tomatoes, provide them with regular hydration directly at the roots for optimal health. Overhead watering is detrimental as it increases their vulnerability by spreading disease via splashed water droplets that settle on the leaves.
In addition, proper spacing between plants will help you with managing this issue. Proper spacing allows for better air circulation, which helps reduce moisture from collecting on plant surfaces and reduces the spread of disease organisms.
What Are Different Types of Black Spots on Tomato?
If you regularly visit different gardens then you might see there is such a difference in black spot types. Yes, the black spots on tomatoes can be divided into 4 categories; namely-
Bacterial:
Bacterial diseases caused by Xanthomonas bacteria can be a major problem for tomato crops. These bacteria are found in warm, moist climates and can cause black spots on tomatoes.
The symptoms of this disease include discolored patches or spots on the leaves, stems, and fruit of the tomato plant.
In- brief, The spots will start off small and become larger as they grow and spread. Produces the blotchy leaves which can spread to the stems and fruits of the plant.
Fungal:
The most frequent and disastrous problem of tomato plants is caused by fungi. The fungal disease called Septoria leaf spot is the most frequent and destructive problem for tomatoes.
Besides these numerous disease causes- Anthracnose, fusarium wilt, verticillium wilt, Alternaria leaf spot, and cranker can also cause black spots.
Another type of fungus, oomycetes, is the culprit behind those pesky black spots on tomatoes. This particular fungus is called phytophthora infestans or late blight.
Viral:
Tomato spotted wilt virus, Tomato mosaic virus, and Tobacco mosaic virus are three major viruses that cause black spots on tomatoes.
The symptoms of these diseases range from small dark green spots to yellow rings around the black spots. Thrips and mites are the vectors to carry the virus from one plant to another.
Physiological:
This condition is caused by environmental factors like cold weather, water stress, and herbicides. It can cause black spots on the fruit of tomato plants.
These spots are usually flat or shallow with a tan center and dark brown border. But this one is manageable if you can control the environmental factors to which tomato plants are exposed.
Conclusion:
In the end, I will suggest not getting any high-dose fungicide before observing the types of black spots and their symptoms. Especially if you grow your tomatoes for home purposes, try to use natural remedies as much as possible.
After that, if you think this is time to use chemical fungicide otherwise the vegetation and spots will gradually increase, then use it carefully and strictly according to the instructions.
If you take proper precautions, follow natural remedies, and use chemical fungicides when necessary, I hope your garden will be free from black spots on tomatoes in no time.
I am a graduate of Bangladesh Agricultural University, where I delved into various agricultural disciplines, equipping me with a profound understanding of agriculture. Beyond academics, I have hands-on experience in gardening and crop cultivation. My passion is to embrace sustainable farming and horticulture. With a BSc in Agriculture, I am dedicated to promoting environmentally conscious and efficient agrarian practices.
Bachelor of Science (BSc) in Agriculture (Hons.)
Master of Science. (Sustainable Agriculture & Food Security ) (MS)
Bangladesh Agricultural University