This is a comprehensive guide that will aid you in identifying and controlling one of the most destructive tomato pests, hornworms.
Read further for more!
- What Is Hornworm And How It Harms Tomato Plants?
- How To Confirm That Hornworm Is Troubling Your Tomato Plants?
- Natural Ways To Control Hornworm On Tomato Plants
- Physical Ways To Control Hornworm On Tomato Plants
- Chemical Ways To Control Hornworm On Tomato Plants
- How To Prevent Hornworm In Tomato Plants?
- What Causes Hornworm Attacks In Tomato Plants?
- Frequently Asked Questions
What Is Hornworm And How It Harms Tomato Plants?
Tomato hornworms are large, thick green worms with V-shaped markings and distinctive black horns. They grow to about three to four inches.
They are voracious feeders that can completely defoliate tomato plants.
How To Confirm That Hornworm Is Troubling Your Tomato Plants?
Check the tomato plants for hornworms at least twice a week. These worms are easy to spot due to their sheer size. You may find significant parts of the leaves, stems, and tomato fruits vanish overnight if there is a tomato hornworm.
Another telltale sign of hornworms is the presence of small fecal pellets under damaged areas.
Here is a video on different ways to identify hornworms:
Natural Ways To Control Hornworm On Tomato Plants
The hornworm infestation on tomato plants can be controlled using natural products, including Bt, garlic flakes, DE, and neem oil. These are low toxic and do not harm beneficial insects.
1. Spread Garlic Flakes Around The Plants
Tomato hornworms do not like the strong scent of garlic flakes. Spreading garlic flakes will control the tomato hornworms from chewing the plants.
- Spread garlic– Place garlic flakes around the soil of your tomato plants. This will deter the pesky worms from eating your tomato plants.
- Garlic spray- Alternatively, you may crush two pods of garlic and dilute them in a liter of water. The strained liquid can be sprayed on the plants to deter tomato hornworms.
2. Spray Neem Oil
Neem oil is a natural pesticide that can be effective against hornworms. One downside is that it may damage beneficial insects.
- Prepare the neem oil spray– Mix a tablespoon of neem oil in two cups of water. Transfer to a water spray bottle.
- Spray the affected foliage– Spray the entire infested foliage with the neem oil. Take care to focus on the undersides of the leaves where the eggs are located.
For more information on using neem oil to control hornworms, click on this video:
3. Dust Diatomaceous Earth Powder
Diatomaceous earth is a natural substance made of fossilized remains of diatoms. It will dry up the natural juices of the insects and kill them.
- Dust DE powder– Apply food-grade DE powder to the plants and around the base of the plants. I prefer to wear a dust mask to avoid inhaling.
- Reapply the powder– Reapply the powder after rain or when required.
4. Spray Bt
Bt is a bacterium that is effective against leaf-feeding worms. It acts as a stomach poison and kills young hornworms.
- Prepare the Bt spray– Dilute the Bt with water and transfer them to a spray bottle.
- Reapply the spray– You may reapply Bt spray to the plant foliage as required and after rain.
You may go through this video on using Bt for controlling hornworms:
Physical Ways To Control Hornworm On Tomato Plants
Handpicking is the most effective and non-toxic way to control hornworms on tomato plants with time and patience. You may also create a barrier around the tomato plants to deter hornworms.
Method 1- Handpick Hornworms
Handpicking hornworms are the most effective way of controlling them on tomato plants. They are easy to locate because of their large size.
- Locate the worms– Inspect the tomato plants and handpick the worms if you locate them. You may wear gloves for easy handling.
- Crush the worms– Destroy the picked worms. You may plunge them in soap water to kill them or the worms can be fed to chickens. It is preferable to leave the worms with white rice-like egg cases as they may soon die.
Method 2- Create Barriers
Another way to deter hornworms from crawling into tomato plants is by creating a barrier around the tomato plants.
- Create a barrier– Spread a thin layer of pencil shavings or wood chips around the base of the tomato plants. The sharp edges of these barriers will prevent the hornworms from chewing on tomato plants.
Chemical Ways To Control Hornworm On Tomato Plants
The mild insecticidal soap can work effectively to control hornworms on tomato plants. You may try spinosad to kill larvae.
Method 1- Spray Spinosad Solution
Spinosad is an effective insect control agent for hornworms. It is effective in deterring caterpillars by affecting their nervous system and is less toxic to natural enemies.
- Spray spinosad– Dilute the spinosad concentrate according to the manufacturer’s instructions. Spray on the infested foliage. It works best on newly hatched larvae.
- Reapply the spray– Repeat after one or two weeks as required, according to the severity of the infestation.
Method 2- Apply Insecticidal Soap Spray
The insecticidal spray is effective against small hornworms. It has to be directly in contact with the leaves to be effective. It is safer as it has little activity against beneficial insects.
- Prepare the insecticidal spray– Mix two tablespoons of soap and a tablespoon of cayenne pepper in a liter of warm water. Spray this solution on the infested leaves.
- Repeat the application– Repeat the spray as required as there is no residual activity.
How To Prevent Hornworm In Tomato Plants?
The first step in preventing tomato hornworms is tilling the soil after harvest and rotating crops. Also, planting companion crops and encouraging beneficial insects around tomatoes will help in deterring hornworms.
1. Change The Garden Environment
Till the garden soil after harvesting tomatoes. It helps in destroying the burrowing caterpillars and pupae. Also, remove weeds to prevent the worms from hiding and laying eggs.
Also, practice crop rotation with crops that are not susceptible to hornworms. It will help in keeping the population levels low in individual fields.
2. Practice Companion Planting
Try interplanting dill, basil, or marigolds with tomato plants. It will keep the hornworms away from the tomato plants next year.
3. Encourage Hornworm Predators
Encourage parasitic wasps around the garden. It will deter the hornworms from damaging the crops. Other beneficial insects, like ladybugs and green lacewings will feed on young hornworms and help in maintaining the biodiversity of the garden.
Here is a good video on using beneficial insects to control hornworms:
What Causes Hornworm Attacks In Tomato Plants?
Tomato hornworms usually attack tomato plants in midsummer. They will continue their attack throughout the growing season. Also, untilled soil and weed infestation will favor the hornworm attacks in tomato plants.
But, they do not prefer direct sunlight. They stay in the shaded part of the plant during the day and come out from dusk to dawn.
Frequently Asked Questions
Both tomato and tobacco hornworms are closely related. Tobacco hornworms have parallel white stripes with black spots and red horns on their tail. Tomato hornworms have white V-shaped markings with a black horn.
Yes, tomato plants may recover after you remove the hornworms. You may try various natural ways to control the hornworm population. Add an extra boost of organic fertilizers to help the plants regrow the lost foliage.
No, tomato hornworms do not sting. They do look fierce and dangerous but cant sting. As they are harmless, you may pick them by hand without any danger.
I hope this guide with details of the natural, physical, chemical, and prevention methods will help you control tomato hornworm infestation in your garden.
Please let me know if you have any other method that has worked for you.
Do share the guide with your gardening friends!
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