Septoria leaf spot is a devastating fungal disease of the plants. If you are a tomato cultivator then we assume, you must know the pain of seeing your healthy tomato plants become defoliated and die so quickly that you begin to curse your fate.
Believe us, we can understand your pain that's why, we've come forward with this exclusive guide especially targeting septoria leaf spots in tomatoes and the best possible ways to treat them.
Septoria Leaf Spot on Tomato
Septoria leaf spot is a fungal disease infesting tomato plants, primarily caused by the fungal pathogen, Septoria lycopersici. This disease is found to quickly spread causing shocking defoliation and reduced fruit production of the plant.
The black spots on the tomato leaf are usually small and circular with black-brown coloration. These fungi have been found to attack the older and lower leaves of the tomato plant at the initial phase and gradually spread upward affecting the whole plant in no matter of time.
The Septoria leaf spot is not very complicated to locate in the plant. Early identification can play a prominent role in preventing the spread of fungal disease, minimizing the potential damage of tomato plants.
You should be aware that this disease can develop at any stage of the tomato plant, although they majorly infest the leaf of the tomato, they are equally likely to appear on the stems and blossoms as well. Tomato fruits are only the element likely to be not affected by the septoria leaf spot.
Some of the distinct symptoms of the septoria leaf spot on the tomato plant are provided below:
1. Circular Spot on the Leaf
If you closely observe the undersides of the tomato leaves, specifically the lower and older ones, you might find a circular spot on them. These spots are small usually 1.6-3.2mm in diameter having a dark brown color and light gray center.
Once established, the spots on the leaf will get larger over time. If you've got a magnifying lens then you can try seeing the fruiting bodies of the fungus which look more of a kind of dark brown pimples.
2. Yellow-Brown Leaf and Defoliation
The infested leaves will slowly turn yellow and eventually brown if you let the infestation flourish. Initially, the lower portion of the tomato plant will start to show symptoms that gradually move upward.
In the end, the septoria leaf spot will cause defoliation, losing all the leaves and exposing the tomato plant. This will weaken the plant snatching all the ability to photosynthesize and produce fruits.
Key Factors of Septoria Leaf Spot Development
The primary cause of septoria leaf spots on tomato plants is the infestation of a fungal pathogen referred to as Septoria lycopersici. Several factors are responsible for the development and spread of this pathogen on tomato plants. Scroll down to learn about them:
1. Fungal Spores
Septoria lycopersici is capable of producing spores, which are reproductive units or cells that can germinate into new individuals without potential sexual fusion. These spores are found to survive in the soil, debris of the infected plants, and even in the seeds of plants.
The spores can rise and become active whenever the environmental conditions are in their favor. These fungal spores are found to travel a great distance in search of the ideal conditions for them to thrive.
2. Environmental Conditions
The fungus prefers warm and humid environments having temperatures between 60-80 degrees Fahrenheit. If moisture on the leaves is allowed to remain for prolonged periods, the spores are more likely to germinate and infest the plant.
The moisture development on the leaves can occur through rain, dew, or overhead irrigation. If the ideal condition of high humidity and warm temperature is consistent around the surroundings where you are growing your tomatoes, the fungus spores are highly likely to infect the plant.
3. Water Issues
Another highly likely factor of black spot development on the tomato plants is through water splashing. Yes, water splashing from the rain or overhead watering has been found to spread fungal spores from the infected soil or plant debris to new healthy plants.
Further, insects, people, or any tools and equipment are also equally likely to spread the infection if they come in direct contact with the fungus. Once they get to land on the leaves, they can quickly germinate and begin their infestation process.
Overcrowded planting on the field and dense, thick leaves of the plant are found to keep the moisture as it is for an extended period. If adequate air circulation is not provided to the plants, it can slow down the drying period of the leaves.
Thus, proper air circulation is very crucial to minimize the septoria leaf spot infestation on your tomato plants as it can lower the humidity and enhance the drying mechanism of the leaves.
5. Infected Plant Debris
The debris of the infected plants has the potential to provide shelter for the overwintering pathogen in the soil. The remaining such as leaves stems, and fruits of the plant are found to harbor the fungus, especially, during the winter.
If your plants were infected in the previous growing season and there is still some of their debris left on the ground then there's a high possibility that the fungus is still on the them waiting for their chance.
Septoria Leaf Spot Treatment
Septoria leaf spot is a dangerous and destructive disease that can completely shut down your tomato plants even before you try to pronounce their full name. Yes, they are that quick and so stubborn, it seems an extremely difficult task to treat them once established on the plants.
Treating the black spots of the tomato plant leaf, however, can be achieved to some extent if they are detected quite early but you've to go after them with sheer determination. Let's explore the possible treatment strategies for the septoria leaf spot.
1. Eliminate the Infected Leaves
If you notice small, circular dark brown spots on the underside of the tomato leaves then you should know that your plant has already been attacked by the septoria leaf spot. You've done a good job catching them early.
Now, you need to carefully detach the infected leaves and dump them far away from your house or directly into the garbage disposal. Yes, make sure to destroy them or burn them right away. This will help to prevent the spread of the infection further. Keep in mind not to compost the infected leaves, do not let that come even in your dream!
2. Improve Air Circulation
Another important thing you've to do without further delay is to ensure proper air circulation around your tomato plants. You can achieve this by thinning out the plants. Make sure to prune the excess foliage, especially the lower ones that are close to the ground.
You need to develop the habit of planting your plants by allowing them proper space so that they've plenty of room to breathe and grow. Improved air circulation will reduce the humidity while promoting the faster drying rate of the foliage.
Mulching is the process of adding a thick layer of organic matter such as straw, grass clippings, or wood chips around the base of the tomato plant. This is another great way to prevent the soil from splashing into the leaves of the plant.
If you minimize the potential of soil splashing, you also minimize the potential spread of the fungal spores. In addition to that, mulching is also found to help retain soil moisture to a great extent. Keep in mind to mulch a few inches away from the stem of the tomato plant!
4. Watering Practices
Whether it is a tomato plant or any other house plant, water is essential to each one of them and just like that, watering technique is also equally important. It has been recommended to follow drip irrigation system as much as possible or use of soaker hose to minimize the possibility of wetting the leaves.
Make sure to avoid the overhead watering facilities and keep in mind to water your tomato plants early in the morning. This will help the moisture to dry pretty quickly, reducing the risk of fungal infections.
5. Implement Crop Rotation
Rotating crops simply means avoiding planting the same crops over and over again in the same location. It has been suggested to replace the crop every 2-3 years so that you can cycle of diseases. This will also reduce the chance of fungus surviving in the soil.
It has been recommended to plant crops other than those belonging to the Solanaceae family members (potatoes, eggplants, or peppers). Therefore, it would be best to rotate the crop with nonhost crops like beans, corn, or lettuce.
6. Apply Fungicides
If septoria leaf spots are still not showing any sign of slowing down then you might want to lean on the fungicides. But you should know fungicides are not meant to revive the infected leaves rather they'll assist you in preventing the infestation further.
You can choose between the two types of fungicides to apply against the black spots on your tomato plants.
1. Organic Fungicides
Neem oil as an organic fungicide has been found to work pretty effectively in controlling the septoria leaf spot. Similar to that, any fungicides that are rich in copper content are suggested to be used against black spot tomato leaves.
It has been recommended to use the fungicides by rotating with different modes of medium and action. This is because you do not want the fungal bacteria to get used to your repetitive action, developing resistance against your fungicides.
2. Chemical Fungicides
Choosing chemical fungicides for your tomato plants should be done very wisely. You need to purchase the one that has been labeled as use on the tomatoes only. Chemicals such as copper, chlorothalonil, and mancozeb are suggested to be applied against the septoria leaf spot.
You need to apply the fungicides as soon as the potential signs of infestation are identified on your tomato plants. Make sure to follow the instructions properly before using the fungicide spray.
Once you use the gardening tools to work on your field, especially on the infected plants, you should immediately disinfect those tools before they make any contact with other things. This will prevent the risk of spreading fungus to the healthy plants of your garden.
You can make a disinfectant solution by mixing a small amount of bleach with sufficient water in a ratio of 1:9. Then, apply this solution over the gardening tools very carefully. Keep in mind to wear protective gloves and cover your exposed skin while handling the infected plants.
How to Prevent Septoria Leaf Spot Infestation
You can adopt some effective practices in your gardens to prevent the septoria leaf spot infestation. Basically, these practices will try to minimize the thriving conditions for the fungal bacteria to grow and spread.
Integrating effective preventive measures in your gardening routine is found to help reduce the risk of deadly fungal infections on your tomato plants. Let's learn about the preventive measures in a more detailed way:
You shouldn't keep the seeds from the infected plants. Although there has not been any significant evidence that supports the fact that the fungus is carried out by the seeds, you've nothing to lose by not using those seeds to grow the new plant.
Not only that but for any seeds you've stored or have been thinking of using for plantation, make sure you treat or process them effectively so that any potential bacteria or disease is eliminated from them.
2. Clean Your Garden
The fungus has been found to overwinter on the debris of diseased plants, especially after the end of the growing season they silently hide underneath the soil. You need to clean your garden by disposing of all the debris from the garden such as fallen leaves, stems, and fruits.
You can try making some sort of bar or covering around your tomatoes so that it is prevented from touching other plants. Make sure you destroy every piece of infected plant debris by burning them or treating them at very high temperatures.
3. Practice Good Watering Technique
Many people are unaware of the good watering practices. You shouldn't be one of them. Here's the thing, you should avoid overhead watering which has been found to wet the leaves of the plant and also may cause water splashing.
Whenever you think of watering your tomato plants, make sure you water them directly at the base. You can also try using drip irrigation or soaker hoses method to water the plants. Develop the habit of watering early in the morning and evening.
4. Try Planting Disease Resistant Cultivars
Although there have not been developed any such cultivars of tomato that can completely resist the septoria leaf spot infestation, you can still go for some of them that have been found to show greater tolerance.
Yes, some breeds of tomatoes can tolerate the disease and infection risk to a large extent potentially ignited by the septoria leaf spot. You can search for the one that is suited to your local growing conditions.
5. Make Use of Baking Soda and Vegetable Oil
Baking soda and vegetable oil are taken as a natural fungicide. You can try using the solution of natural fungicide on your healthy tomato plants to prevent the risk of septoria leaf spot infestation.
You need to mix one tablespoon of baking soda, and one teaspoon of vegetable oil with one gallon of water mixed with a few drops of dish soap to prepare the solution. This solution if applied regularly in the morning or evening on the leaves and stems of your tomato plants, helps to keep the fungal bacteria at bay.
How To Boost Tomato Plant Immunity
The immune system of the tomato plant is just as important as any other essential element to stand robust against any kind of infection or disease. One of the popular, easy, and effective natural homemade remedies to give a boost to your tomato plants is discussed below:
Nettle manure, also known as nettle tea or nettle fertilizer, is a product of stinging nettle, in fact, a result of fermenting nettles in water. Stinging nettle is a type of weed that has been found to possess a wide variety of beneficial elements to be used as a garden fertilizer.
This can be an excellent choice to help boost your tomato plants because it is highly rich in nitrogen, minerals, and essential elements that help to strengthen the immune defense of your plants against diseases and parasites.
How to Prepare Neetle Manure
Please follow the below-mentioned instructions to prepare nettle manure:
Begin by harvesting around 1 kg of fresh nettles. Make sure to avoid seed and flowering nettles.
Nicely chop down the nettles into fine pieces and place them into a container.
If you've stored rainwater in your garden, make use of it by adding it to the container. You can also use non-chlorinated water.
Properly mix the water and nettle pieces and leave them for around 10-15 days.
In the meantime, you should stir the mixture regularly.
Now, you need to filter out the liquid using a clean cloth.
Store the liquid fertilizer thus, obtained away from the direct sunlight.
This liquid fertilizer can be used in different ways to boost the tomato plants. For effectiveness, you can use them either by diluting them with water and applying them on your plants regularly for around 10 days or by filling the diluted solution in a spray bottle and applying them on the tomato plants.
Either way, you can help to nourish the roots of the plants and strengthen their immunity to fight against diseases and infections like septorial leaf spots.
