Aphid Infestation: Protecting Your Tomato Plants

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Video aphids on tomato plant

Aphids, those pesky little pests, are a common nuisance when it comes to growing tomatoes. These tiny creatures can be found worldwide, feeding on the sap of your tomato plants and multiplying at an alarming rate.

Not only do aphids cause damage to your plants, but they can also transmit viral diseases. Severe infestations can result in curling, yellow leaves, and a decrease in tomato production. And it’s not just tomatoes that aphids target – they can be found on a wide range of fruits and vegetables, as well as flowers, shrubs, and trees in your landscaping.

Effective Natural Control of Aphids

The good news is that managing aphids in your vegetable garden is not a difficult task. In this article, we will explore several organic and natural methods to keep these persistent insects at bay.

Identifying Aphids

Aphids come in various colors, such as green, red, white, and black. They are tiny, about the size of a sesame seed. On sunny days, they seek shelter on the underside of leaves, along the stem, and even on the flowers of your plants. As they molt and grow, they leave behind delicate white shells that can be mistaken for living pests.

A single aphid can quickly multiply into an infestation of hundreds or even thousands within a couple of weeks. While most aphids cannot fly, they can develop wings if the plant becomes overcrowded, allowing them to search for new host plants.

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Recognizing Aphid Infestation

In the early stages, aphids may go unnoticed. However, as their population grows, you may observe misshapen, curled, and yellow leaves on your plants. The presence of aphids can cause your tomato plants to suffer, leading to reduced productivity. If aphids transmit a viral disease, symptoms such as yellow spotting, brown leaves, and even plant death may occur.

One of the telltale signs of aphids is the sticky substance they leave behind on leaves and fruit. This substance, known as honeydew, is a byproduct of their sap-sucking activity. The honeydew can attract black sooty mold, which can further harm your plants.

Ants and Aphids

Ants are often found alongside aphid infestations. They are attracted to the sweet honeydew produced by the aphids. In some cases, ants even protect and “farm” aphids, ensuring a continuous food source for their colony. Some ants release a chemical that sedates aphids, causing them to remain near the ant colony.

Organic Methods for Aphid Control

Regularly checking your plants for aphids is essential due to their rapid reproduction rate. When dealing with a minor infestation, you can manually remove aphids by squashing them or using a strong spray of water. However, be cautious as excessive water pressure may harm the plant.

Predatory insects like aphid midges, lacewings, and ladybugs naturally prey on aphids, providing a helping hand in controlling their population. Additionally, there are parasitic wasps that lay their eggs inside living aphids, causing them to perish.

For severe infestations, diatomaceous earth (DE) is a commonly used and effective option. DE is a powdered substance made from crushed fossils that are abrasive to the soft skin of aphids. It dehydrates and kills them upon contact. However, take care when using DE to avoid affecting beneficial insects like bees.

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Aphid sprays made from horticultural oils, insecticidal soaps, neem oil, or homemade remedies are also effective against aphids. These sprays can be enhanced with ingredients like eucalyptus oil, lemon oil, lime oil, crushed garlic, or pepper sauce.

Companion Planting and Other Techniques

Incorporating companion plants like marigolds, nasturtium, mint, tansy, or cilantro can help deter aphids from your tomatoes. It’s important to position these companion plants close together with your tomatoes for maximum impact. Mint can be placed in pots to prevent it from spreading and to raise its level near the tomato plants.

Yellow sticky boards attract aphids and other insects, enabling you to catch and control their population. Reflective mulches, such as aluminum foil, can also confuse and repel aphids when placed around the base of your plants. However, remember to remove the reflective material during hot summer months to prevent heat damage.


Maintaining the health of your plants is crucial when it comes to pest control. While aphids can cause concern, selective use of organic methods mentioned above should be sufficient to support your tomato plants without adding unnecessary effort or chemicals to your garden.

Remember, a beautiful and bountiful tomato harvest is within reach, even in the presence of these tiny intruders.

Ames Farm Center