Septoria Leaf Spot is a fungal disease that can occur in your plants. How can you save your plants from it? We have all the answers you need! – Gro Indoor
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Septoria Leaf Spot: Causes, Prevention, and Treatment

by 09 Apr 2023

Septoria Leaf Spot: Causes, Prevention, and Treatment

Growing plants involves dealing with several challenges, and one of them is the Septoria leaf spot. The septoria leaf spot is also called a 'yellow leaf spot.' As the name suggests, these are areas of discoloration that can appear on your plants' leaves due to plant disease.

Thankfully there's no need to worry if your plant has developed yellow spots. The disease won't kill your plants, but it can definitely affect their flowering and production. Therefore, it is necessary to detect, prevent, and treat Septoria's illness in case it has spread to your plants. Now, let's dig into the details.

What is Septoria Leaf Spot?

Septoria leaf spot is caused by a fungus called Septoria lycopersici. It usually occurs on the lower leaves that grow after the first fruit sets. This plant disease is among the most harmful diseases of tomato foliage. Even though it occurs mostly in tomato plants, there is a possibility that this disease can affect any other plant in the Solanaceae family. It tends to be severe in wet areas with prolonged humid weather.

Most of the time, the Septoria leaf spot is treatable, and you can control its spread. Remember, it is not advisable to leave it untreated because that could lead to your plants looking sick and having stunted growth. Its impact can vary from hindered flowering to the plant dying. You can't afford to ignore the Septoria leaf spots, so learn how to identify Septoria leaf spots in their early stages.

How to Identify Septoria Leaf Spots?

Fortunately, it is not difficult to detect Septoria leaf spots because of the yellow or brown spots it causes on the leaves. Some growers may get confused after seeing these spots, thinking that their plants are dying. However, the fact is that this disease can be easily controlled and treated. All you need to do is to stay vigilant and take prompt action. Here are the signs that can help you diagnose Septoria leaf spots in your plants.

Spots Start Appearing on the Underside of the Leaves

The yellow or brown spots caused by Septoria leaf spot diseases first start appearing on your leaves' underside. Therefore, this is the part of your plants that you should keep an eye on. After these spots appear significantly on the undersides, they begin appearing on the leaves topside.

There can be exceptions in some cases, as the spots might not appear on the leaves underside first. In any case, you will be able to detect more spots on other parts of the leaf. The important thing to remember is that when the spots are only on the leaves underside, the disease can be caught early on. This way, it is easier to treat it. When the spots have spread to other parts of the leaf, it means that the disease's progression is now advanced, making it harder to treat.

Spots Become Larger and Merge Together

The first appearance of the spots is in the shape of tiny splotches around the leaves. However, you will notice that these small spots will grow into larger ones with the time and ultimately merge together consuming the entire leaf. This is when there should be no further delay in the treatment; otherwise, the damage can be irreversible.

Leaves Eventually Dry Out and Die

The Septoria leaf spot's natural course involves the leaf getting covered by spots, drying out, withering away, and eventually dying. Clearly, prompt action is needed to save your plant from dying. It would be best to take the appropriate measures as soon as you notice these unusual spots and prevent the fungus from taking over your plant. If the fungus gains full control of your plant, it can result in its death or at least cause unhealthy plants that are unable to flower properly or produce just a low yield of a low-quality flower.

What are the Preventative Measures for Septoria Leaf Spots?

Fortunately, preventing the Septoria leaf spot is simple. All you need to be careful about is maintaining the perfect grow room environment for your plants. This can be done by keeping a check on temperature and humidity. When these are maintained optimally, the likelihood of fungus development is decreased.

When your plants are exposed to excessive moisture, particularly the leaves, it encourages fungus growth.

Therefore, you should set up a ventilation system to keep moisture and temperature levels under control. In extreme cases, you might need a dehumidifier or air conditioner. It is also crucial to keep your grow room clean. Clean the area from dead plant matter, plant clippings, fallen leaves, and other rubbish. This disease is also more common outdoors because fungus and mold spores may invade your garden through the wind.

Still, the fact of the matter is that regardless of how correctly you may have done everything, your plants can still develop Septoria leaf spots. So, the best thing to do is to keep a check on your plants to detect any signs early on. Fortunately, we are here to share the best spot treatment tips for your plants.

How to Treat Septoria Leave Spot A Step-by-Step Guide

Once you have successfully detected the Septoria leaf spot, you must take immediate action before the fungus spreads like wildfire and harms your entire garden. Here are the steps to follow to prevent the occurrence of Septoria leaf spots at home beginning with the least invasive methods and ending with fungicides.

Manually Remove Infected Leaves

Use your clean hands to manually remove any infected leaves that you locate on your plants. Make sure to do this gently because pulling too hard can result in the spreading of the fungal spores onto unaffected leaves. This can cause the fungus to spread further. Pluck out each affected leaf and collect it in a bag.

You can protect your skin from getting exposed to fungus by wearing gloves. Also, you must wash your hands properly with soap and water once you are done.

Use a Fungicide

A fungicide is understandably the most convenient and effective way to remove fungus from a plant. There are several brands of fungicides available in the market, but we have listed our top recommendations later in this article, so be sure to check those out!

Some growers are concerned about the use of fungicide in their gardens or grow rooms. The fact is, they are completely safe if you use them properly. In many cases, they are why some plants are saved from dying, and your money and time do not go to waste.

Choose the right fungicide, and it will do the rest. It will hunt down the fungus' tiniest traces, even down to the roots, and kill it all. Typically, applying the fungicide is super easy, provided that you follow the manufacturer's instructions and give it time to show results.

Monitor the Process of Removing the Fungus

You will see visible results in a week after using a fungicide or removing infected leaves. If the problem persists even after a few weeks, you should think about removing the plant altogether. This is necessary to stop the spread of the fungus across your grow room or garden. Don't be sad about this. A diseased plant cannot yield much anyway, and you need to protect your healthy plants by removing them.

Our Top Recommendations of Fungicides for Septoria Leaf Spot Treatment

Here are our top recommendations of fungicides that you can use to combat Septoria leaf spots in your plants.

Safer Brand 3 in 1 Garden Spray Concentrate

Safer Brand is a respected name in the gardening sector. It is known for fighting off a variety of molds and fungi. Fortunately, its magic works on Septoria leaf spots too. This fungicide solution is a concentrate, which means that you will have to add some water to it to make it dilute enough to spray onto the leaves.

This characteristic makes it extremely affordable because, with just one bottle, you can cover as many as 13,600 square feet! Safer Brand 3-in-1 comprises a powerful mix of sulfur fungicide and insecticidal soap (potassium salts of fatty acids). This combination acts super fast to eliminate fungal diseases from your plants.

General Hydroponics Defguard

General Hydroponics Defgaurd is among the best fungicides in the market. It is both a bactericide and a bio-fungicide and is OMRI listed. This means that it has been tested and declared organic by the highest possible standards. General Hydroponics Defguard is useful for all types of mold and fungal issues, including Septoria leaf spots. You may also use it preventatively.

Organocide Plant Doctor Systemic Fungicide

Organocide Plant Doctor Systemic Fungicide is another great option. The Plant Doctor Fungicide is a broad-spectrum, earth-friendly disease control solution that is useful for all types of plants. Being systemic means that it can work its way through your entire plant to eliminate the disease thoroughly. It applies to the Septoria leaf spot as well.

This fungicide has additional benefits too. For instance, it can help promote the plant's metabolism. Consequently, your plant will flower well, grow faster, and become happier and healthier overall. Not many fungicides have claimed to do that!

Do You Need Assistance with Treating Pests and Diseases in Your Plants?

Are you struggling with pest/disease issues like the Septoria leaf spot? Reach out to the experts at We can assist you in devising an action plan to combat any plant health issues. Also, we can help you maintain the ideal environment in your garden or grow room.

We cater to other needs of growers too. For instance, you can get grow tents, hydroponic systems, and more pest-control products. We are proud to announce that we are a one-stop shop for all your horticulture needs. We offer you high-quality services at the lowest possible prices. Get in touch with us today and find the solutions to all your growing needs!

Sep 20th 2022
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