are aphids bad for tomato plants

Are Aphids Bad for Tomato Plants? Understanding this Common Garden Pest

Aphids are a common pest that can wreak havoc on tomato plants. But how bad are they really for your tomatoes? Let’s take a closer look at these tiny insects to find out.

What Are Aphids?

Aphids are small, soft-bodied insects that feed by sucking sap from plants. They come in many colors like green, yellow, brown, red or black. Aphids have pear-shaped bodies and long legs. They can be winged or wingless.

There are around 250 different aphid species. Some are specialists that only feed on one type of plant. Others are generalists that eat multiple plants. The most common aphid attacking tomatoes is the green peach aphid.

How Do Aphids Harm Tomato Plants?

Aphids can damage tomatoes in several ways:

• Sucking Sap – Aphids pierce plant tissues with mouthparts and suck out sap. This weakens and stunts plant growth.

• Spreading Diseases – Aphids transmit viral diseases as they feed, including tomato yellow leaf curl virus and potato virus Y.

• Secreting Honeydew – Aphids excrete a sticky, sugary substance called honeydew. This encourages mold and attracts ants to “farm” them.

• Deforming Plants – Large aphid populations cause leaves to curl, twist, yellow, wilt or drop. Flowers may not develop properly. Plants become stunted.

So yes, aphids can definitely be detrimental to tomato plants! Uncontrolled aphids seriously reduce yields.

Aphid Life Cycle

To control aphids, it’s helpful to understand their life cycle:

• Eggs – Females reproduce without mating, birthing live nymphs. They also lay overwintering eggs on leaves in fall. These hatch in spring.

• Nymphs – Young wingless aphids resemble small adults. They immediately start feeding and maturing.

• Adults – Winged adults spread to new plants. After landing, they shed wings and reproduce quickly.

• Rapid Reproduction – Each female can birth up to 12 nymphs daily. Nymphs mature in 7-10 days.

Populations explode from a few to thousands in weeks. Hitting them early is key.

Signs of Aphids on Tomatoes

Watch for these signs of aphid infestation:

• Clusters of small, pear-shaped bugs on undersides of leaves and stems. May be green, yellow, brown, red, black or white.

• Curled, wrinkled or deformed leaves. Stunted plants.

• White shed aphid skins after molting look like flakes.

• Honeydew makes leaves shiny/black with sooty mold.

• Yellow spots on leaves or twisted new growth can indicate virus transmission.

Inspect undersides of leaves to spot aphids before populations surge. Check new growth first.

Controlling Aphids on Tomato Plants

Act quickly at first signs to prevent major damage. Effective control methods include:

Organic Approaches

• Insecticidal soaps – Disrupt aphid cell membranes. Hit insects directly. May need multiple applications.

• Neem oil – Blocks breathing. Coat young nymphs before populations spike.

• Horticultural oils – Smother aphids and larvae. Less toxic than pesticides.

• Pyrethrins – Attack insect nervous systems. Often combined with piperonyl butoxide.

• Beneficial insects – Ladybugs, lacewings, etc. eat aphids. Plant flowers to attract them.

• Strong water spray – Knocks off some aphids. Repeat every few days.

• Row covers – Form physical barriers with fabric. Bury edges in soil.

Chemical Pesticides

• Insecticidal soaps – Stronger concentrations than organic ones. Require direct contact.

• Malathion – Broad spectrum organophosphate. Kills on contact. Toxic to bees.

• Imidacloprid – Systemic neonicotinoid pesticide. Absorbed by plants, kills sucking insects for weeks.

Only use pesticides as a last resort, following all safety guidelines. Many harm bees and wildlife. Consider your whole garden ecosystem.

Natural Aphid Prevention Through Companion Planting

Certain companion plants naturally deter or control aphids, thanks to chemicals they release. Try interplanting:

• Marigolds
• Chives
• Garlic
• Petunias
• Radishes
• Coriander
• Dill
• Nasturtiums

Crop rotation and weed removal also help by eliminating overwintering eggs. Controlling ants reduces aphid farming. Use sticky barriers on stems.

When to Take Emergency Action Against Aphids

Bring in the big guns if you see:

• 50+ aphids per leaf
• Rapid spread to new colonies
• Severely curled or yellow leaves
• Stunted flowers and fruit
• Signs of viruses

At this point, organic methods may not be enough. Consider chemical pesticides according to label directions to save plants. Always inspect tomatoes regularly and take action at the first signs of infestation for best results. With diligence, you can protect your crop from aphid damage.