Seedling diseases of tomato:

Have noticed this unfortunate chain of events whenever you plant tomato seeds in a nursery?

The tomato seeds germinate very well.

As the seedlings grow in size, some of them get infected by a strange disease.

Slowly by slowly, some of them start dying.

In a few days, you find out that you’ve lost 25%, 30% or even 50% of the seedlings.

If you’ve ever faced this problem, you are in the right place.


In this blog post, I am going to share tips and strategies about:

  • The causes of tomato seedling diseases in a nursery,
  • How to stop them forever so that you never lose any of your seedlings to disease,
  • Practices that will keep your nursery free of diseases,
  • Modern tools to help you stop diseases in the tomato nursery.


Continue reading.

Let us start with facts.

Why Seedling diseases of tomatoes are common in Kenya.

A study done by a leading plant scientist revealed some shocking results.

It showed:

“91.3% of farmers lose 53.79% of their tomato seedlings every season to diseases.”

This is a tragic outcome!

No wonder tomato farmers spend 25% more on seed purchase.

Consequently, tomato farmers struggle to break even or to make profit from their farms.

But this is going to be a past thing from today onwards.

For I am going to reveal to you my insider secrets to stopping diseases of tomato seedlings.

That said, let us get into the gist of the matter.

What causes tomato seedlings diseases in a nursery?

It is easy to mention the common diseases in a nursey like:

  • Fusarium wilt
  • Pythium root rot
  • And damping off.

The hard part is to uncover the reasons behind the occurrence of these serious seedling diseases of tomato.

To uncover these reasons, allow me to draw into my 5 years’ experience growing tomatoes.

The journey was full of mistakes, struggles and victories.

And one of the struggles was…

“How do I control diseases in the tomato seedling nursery?”

Fortunately, through trial and error, I was able to learn of effective ways to do it.

So this post is about how I won the war against tomato seedling diseases.

I’ll be sharing it with you, so that I can give you inspiration that you can do it too.

And it’s my hope that you’ll never face tomato diseases in the nursery again.

I will start by sharing my mistakes, then share the proper way to solve them.

So if you find yourself committing a similar mistake(s), you can take remedial action immediately.

Mistake#1: Adding Manure in the Nursery Just Before Sowing Seed

There’s a false belief among farmers that seedlings need manure to grow healthy.

So they go ahead and add lots of manure in the nursery.

This is a fatal mistake that costs farmers big.


When you add lots of manure in a nursery, just before sowing, you create a serious imbalance of soil nutrients.

This is what happens:

  • The levels of ammonia and other forms of nitrogen spike.
  • Organic matter increases,
  • Microbial activity rises more so if the manure is not well rotted

This huge increase in nitrogen levels, creates an ideal environment for tomato diseases.

So when you sow your expensive tomato seed—of course they will germinate rapidly.

However, few days later, you’ll see them become sickly then eventually die.

The correct way of adding manure in a nursery is to do it 3-4 months early before sowing any seed.

This will allow micro-organisms to break down the organic matter and make it perfect for the nursery.

The other reason why I discourage the use of manure in the nursery is to do with the purpose of a nursery.

And it is one:

“To germinate seeds to a suitable age and maturity before the seedlings are transplanted to the field.”

Pause for a moment and think about that statement.

When you think about it, you realize you don’t need so much manure in the nursery.

You just need sufficient amounts of soil fertility to last the seedling until its ready for transplanting.

This said, why do you want to add manure in the nursery during seed sowing?

Mistake #2 failing to treat the soil before sowing the tomato seed

Disease causing funguses like Pythium rot, Fusarium wilt, Bacterial wilt quietly reside in the soil.

Before you plant any seed, you’ll barely notice the existence of these diseases.

Plant your valued tomato seed, a few weeks after they have germinated—you start seeing the symptoms of the diseases.

Assuming that the diseases don’t exist because you can’t see them is foolhardy.

Being wise is taking action against the diseases.

For these reason, you must disinfect the seed nursery before growing any seed.

“So how do I disinfect/ treat the soil?”

You may ask.

Doing this is simple.

In fact, there are three approaches to doing it.

You can:

  • Solarize the soil.
  • Use appropriate fungicides to drench the soil,
  • Add a greater diversity of microorganisms to the soil so that they outcompete the disease causing funguses.

These soil treatment strategies will help reduce the impact of tomato seedling diseases.

I’ll write a more detailed post on soil treatment strategies at a future date.

Therefore, keep checking it out.

Mistake# 3: Overwatering the Tomato Seedlings.

Most tomato farmers are prone to making this silly mistake.

“Why is it so?” You may ask.

They think that the tomato seed nursery must be moist all the time.

This is based on the belief that the seedlings will die if the soil is a little bit dry.

Nothing could be further from the truth.

The truth is that seedlings need sufficient amount of water but not excess.

A few hours of soil dryness aren’t bad or harmful to the seedlings.

Overwatering can lead to several problems in tomato seedlings including:

  • Root rot,
  • Wilting,
  • and stunted growth.

Here are a few tips to help you solve the problem of overwatering tomato seedlings:

  • Ensure Proper Drainage.

Make sure you raise your nursery to allow excess water to drain out.

To improve drainage, you can also add a layer of gravel at the bottom of the nursery.

  • Adjust Watering Schedule

Tomato seedlings need consistent moisture, but not too much.

Water the seedlings only when the top inch of soil feels dry to the touch.

  • Reduce Watering Amount.

When you water your seedlings, water them thoroughly but do not overdo it.

Water until the excess water begins to drain out.

Don’t water again unless the top 1 inch of soil feels dry to the touch

  • Use a Moisture Meter

A moisture meter can help you determine when your tomato seedlings need watering.

Insert the meter into the soil, and it will indicate whether the soil is too wet, too dry, or just right.

  • Improve Air Circulation

Good air circulation helps prevent overwatering and promotes healthy plant growth.

Make sure your tomato seedlings are not overcrowded.

They should have enough space between them to allow for good air circulation.

By following these tips, you can prevent overwatering of your tomato seedlings

Mistake #4 Overcrowding the tomato seedlings

Overcrowding of tomato seedlings can lead to seedling diseases.

For example,

  • Damping off,
  • root rot,
  • and wilts

This is due to increased moisture levels, lack of air circulation, and competition for resources.

Damping off is a serious fungal disease that affects the base of the stem of young seedlings.

It causing them to rot and eventually die.

Overcrowded seedlings provide an ideal setting for the fungus to grow and spread quickly.

Root rot is another fungal disease that affects the roots of the tomato seedlings.

Overcrowding can cause the soil to remain moist for longer periods.

This creates a suitable environment for the fungus to thrive, leading to root damage and stunted growth.

Wilts are caused by a bacterial or fungal infection that affects the water-conducting tissues of the tomato plant.

Overcrowding can cause the plants to compete for nutrients and water, leading to weakened plants that are more prone to diseases.

That’s not all.

Overcrowding also reduces air circulation.

This in turn creates damp conditions that favor the growth of fungal diseases.

Additionally, the lack of space can cause physical damage to the plants.

The plants develop wounds which are entry points for diseases.

To avoid these issues, it is important to:

  • Provide adequate space between tomato seedlings and,
  • Ensure proper ventilation.

Thinning the seedlings and removing any damaged or diseased plants can also help prevent the spread of diseases.

Additionally, providing proper watering and drainage can help prevent the buildup of excess moisture and reduce the risk of disease.

Mistake # 5 Refusing to use modern seed germination technologies like seed trays

Relying solely on soil nurseries in growing expensive tomato seeds has several negative impacts, including:

  • Uneven Germination.

Without using seed trays, it can be difficult to get even germination of the seeds.


The seeds may not be planted at the correct depth…

or they may not receive the needed amount of moisture, light, or temperature.

  • Higher Risk of Disease

Using soil nurseries increases the risk of disease and fungal infections.

The soil may contain pathogens that can attack the seedlings, causing damping off, root rot, or other diseases.

  • Higher Cost

Using soil nurseries may require more space, more soil, and more time than using seed trays, resulting in higher costs.

Additionally, if disease strikes and kills the seedlings, it can be costly to replace the lost plants. 

  • Reduced Control

Seed trays allow for better control over the growing conditions of the seedlings.

Without trays, it can be challenging to monitor and adjust the moisture levels, temperature, and light exposure of each seedling, leading to poor growth.

In summary, while soil nurseries can be used to germinate tomato seeds, using seed trays is generally recommended.

Seed trays provide better control over germination conditions, reduce the risk of disease, and can help ensure even germination rates, resulting in healthier, more uniform seedlings.

Grow Healthy Tomato Seedlings Starting Today

With Seedling trays, you’ll get 100% tomato seed germination rates, Full control over the seed environment of so that they are healthy and capable of producing maximum yield after transplanting, You’ll also have an easy time transporting seedlings during transplanting and much more benefits!amazing seedling tray is great for preventing soil infections


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