If you’ve ever been on the receiving end of the effects of Tuta absoluta, you know that growing tomatoes can be as disastrous as it can get.
I get it – when you’re not sure what to do when tomato leaf miner attacks, but you feel like somehow you’ve got to do something.
So, you result in spraying pesticides unsparingly on your crop.
Unfortunately, the result is often pathetic due to the resistant nature of Tuta absoluta to most pesticides – and that results in unimaginable losses of your crop, investment, and money used to buy chemicals.
That means the best case scenario, your reputation as an agribusiness entrepreneur is dinged for exceeding the Minimum Residue Levels (MRLs).
Worst case scenario, your whole family goes hungry and hates you for making a wrong business decision in case they depended on it.
But there are awesome ways to control Tuta absoluta out there that actually works for everyone.
So what separates the triumphs from the tragedies? And how do you ensure you’re growing your tomatoes successfully free from Tuta absoluta?
We’ll delve into these questions later in this guide.
Just make sure you read up to the end.
But first, let’s dive into what Tuta absoluta is, and what it isn’t.
If you already have some basic knowledge about the pest, please feel free to skip this section and go straight to the control measures.
Biology and Origin of Tuta absoluta
Well, Tuta absoluta’s threat to Solanaceous crops originated from South America before spreading to other parts of the world.
Thus, the pest is sometimes referred to as the South American moth owing to its origin.
The common name for Tuta absoluta is the tomato leafminer, named so because of the pest’s preference for tomato.
This dangerous pest favors tomato (Solanum lycopersicum) and sometimes potato (S. tuberosum).
Tomato leaf moth has a life cycle of 29 to 38 days depending on the temperature.
The pest prefers higher temperatures meaning the higher the temperature, the faster it will reproduce.
Female leaf moths can lay up to 260 eggs for their entire lifetime.
Those are a hell lot of eggs!
I doubt with that kind of reproduction capacity if anyone can salvage their crop from their menace.
The most destructive stage is the larval/caterpillar stage which lives as a miner in the leaf, fruit or stem.
It burrows in and sucks sap from the leaf leaving behind unmistakable marks all over the plant.
What’s even worse is that the adults are very active only during the night.
This makes it difficult for you to detect them early enough, leading us to the next question.
How does Tuta absoluta look like?
It’s important for you to fully understand what you’re up against when dealing with crop pest or diseases.
In this case, you need to understand what the tomato leaf miner looks like.
Indeed, the adult moth has a grey-brown color and approximately 6mm in size. You can comfortably see them with a naked eye.
The only downside like I’ve mentioned before, the adults aren’t active during the day.
The newly hatched caterpillars are 0.5mm and develop a black band behind the head when maturing.
Their backs are pinkish in appearance as you can see in the image above.
A fully grown caterpillar is about 9mm in size.
Now, after exploring what is Tuta absoluta and how to easily identify them, it’s time to understand exactly how they get introduced to your tomato field.
Sources of infestation
The most common source of infestation so far is buying seedlings that have been infected by the moth’s larva.
Therefore, it’s essential to only buy seedlings from certified plant nurseries.
You can further tell a health seedling by looking at the color. Healthy seedlings are strong, vigorous and dark green as opposed to yellowish.
So, do your homework and buy or grow healthy seedlings. This will give your tomato crop a good head start.
Other sources of infestation are wild hosts in the same family as the tomatoes and buying infected fruits at the market.
The former is more common than the latter.
Therefore, you need to ensure that the surrounding crops are either non-solanaceous or free from the pest altogether.
There are reports of Tuta absoluta wiping out the entire tomato crop causing 100% losses!
If you don’t take the necessary precaution measures, you’ll just be part of the statistics.
Thankfully, somehow you’ve stumbled on this article and it might be what will make all the difference.
If there’s anything you need to remember is not to underestimate these ferocious bugs.
Second, pesticides won’t help you much because these very bugs have their own way of dealing with the chemicals.
It’s called resistance!
So, how do you control these bugs?
Much less if you’re just a newbie or beginner in farming?
Bearing in mind their resistant nature to pesticides.
Well, I’ll tell you how.
Just read on.
How to Control Tuta absoluta Even If You’re Not an Expert
There are several approaches that are cost-effective in dealing with these tomato leaf miners.
The first one is to prevent their infestation as much as possible and second, deal with them before they exceed the Economic Threshold Level.
And the best way to deal with them is by using natural ways as much as possible.
Let’s discuss these two approaches further.
But first, you need to identify their initial effects or their presence through regular scouting and monitoring.
Scouting and Monitoring
Scouting entails looking for any abnormal signs on your crop. You should do these as regular as possible to detect any changes earlier enough.
When scouting and monitoring your crop for Tuta absoluta, check for the following symptoms.
If all or some of the symptoms below appear on your plant, then you’ve already been hit and should start taking corrective measures which I will discuss later.
- Blotch-shape mines and under worst cases leaves dying off completely.
- Malformation of the plant caused by the mining of the stem since the caterpillars prefer stems and leaves but also under the crown of the fruit.
- Deformation or curling of leaves and necrotic areas
- The fruit developing an abnormal shape
- Obvious exit holes on the fruit
- Premature fruit dropping or reducing in size
- Lesions and distortion on growing points
- Stems either forms witches broom distorts, die back or wilts altogether
- Damage and fruit developing wounds which in turn serves as avenues to other disease-causing pathogens.
Once you realize that your crop might be or is at risk, act fast by taking any of the following control measures.
Remember that some of them are aimed at preventing while others aimed at eliminating the pests.
Use of nets – Grow your tomatoes inside the insect nets while growing outdoor or within the greenhouse. If growing in the greenhouse, make sure the nets aren’t damaged.
Use of pheromone traps – Pheromone traps attracts and trap all-male adult moths especially when they are active at night. Use 2-4 traps per hectare for monitoring. If the number of trapped moths increases, you need to increase the traps accordingly.
Control human and animal traffic to the fields – Both humans and animals are vectors for spreading the bugs. So it’s important to control how they enter and leave your farm.
Sterilize the soil – Before you plant, ensure to properly sterilize the soil to kill all the eggs that might be present in the soil.
Quality planting materials – Buy quality seeds and seedlings from credible sources to ensure that they have not been infected by the larvae.
- Use dustable sulfur which acts as an effective repellent
- Practice crop rotation with non-solanaceous crops and completely remove any post-harvest plant debris.
- Feed and irrigate your crop properly.
- Completely remove any wild solanaceous host plants in the vicinity
- Proper spacing, weed management, and crop sanitation
- After a growing season (greenhouse), cut all plants above the soil level, leave them to dry out inside the greenhouse before uprooting and transporting debris outdoors for burning.
Control of Tuta absoluta using natural enemies
In case, of low infestation, biological control using natural enemies is the best alternative. For example, you can still use pheromone traps as discussed earlier.
However, this time the traps aren’t for monitoring purposes but for controlling the bugs.
In this scenario, use 25 – 35 traps per hectare, which will trap and kill the males.
Without mating, their reproduction will be hindered!
And that is what we want.
Other than that, the following strategies can also help.
- Use a combination of neem oil (Azadirachtin – kills by suffocation) and Bacillus thuringiesissimply known as Bt.
- Use yellow sticky traps to attract and trap the adults.
Finally, recent studies indicate that biological control services can be ascertained by using potential insectary plants, for example, Achillea millefolium and Calendula officinalis.
These plants serve as nutrient-providers to facilitate the installation of T. absoluta parasitoids (Necremnus tutae, Stenomesius nr. japonicus, and Bracon nr. nigricans) without encouraging the pest.
Chemical Control of Tuta absoluta
If the prevalence of the infestation is high, use the last resort – Spray. Although I’m always skeptical about this.
But sometimes you’ve got to choose a lesser evil.
Try to use either, Deltamethrin, spinosad or Indoxacarb if occasional individuals of Tuta absoluta are observed.
However, don’t bother using pyrethrin-based chemicals.
They won’t help.
Tuta absoluta can and will bring you down to your knees.
They will wipe out all your crop at a snap of a finger when they strike. But the benefits of growing tomatoes and reaping great rewards outweighs the threat of this merciless bug.
Especially when you’re armed with information.
You’ve just read how you can be able to control the bug even when you have zero expertise.
Choose one or a combination of the strategies given and see what works for you.
When you do, please let’s know how it goes in the comments.
Are there any other efficient and environment-friendly ways to deal with Tuta absoluta? Let me know.