Here’s an informative article on ridding your garden of aphids by Megan Hughes for Better Homes & Gardens.
These tiny bugs have big appetites. These simple tactics will help you keep them under control.
Did you know that most gardens host at least a few aphids? On healthy plants, these common insects don’t cause much harm and beneficial insects such as ladybugs help reduce their numbers. Aphids become more of a problem when things get out of whack, usually when plants are stressed by drought, poor soil conditions, or overcrowding. Plus, when garden conditions are just right, aphids can reproduce at amazing speed, creating a huge, hungry colony in just a few days that can literally suck the life out of your plants. The key to dealing with these small but destructive pests is knowing when you need to take action, and then having the right tricks up your sleeve to get them under control.
How to Identify Aphids
Often the first sign of an aphid infestation is not the visible presence of insects themselves. Instead, you’ll see the symptoms of their feeding: twisted and curled leaves, yellowing foliage, stunted or dead shoots, and sluggish plant growth. Damage is usually most noticeable on shoot tips and new growth, along with unopened flower buds. When you take a closer look at these damaged plant parts, particularly on the undersides of young leaves and developing stems, you’ll likely find lots of aphids crowded together.
These insects range in color from green to yellow, brown, red, or even black. Aphids cause damage by sucking sap from tender plant parts. As they feast, they excrete a sugary substance called honeydew. A fungus called sooty mold grows on the honeydew and blocks the amount of light that gets to your plant (but is otherwise harmless). Wash your plant leaves with water to get rid of the honeydew and sooty mold.
How to Get Rid of Aphids
When an aphid population explodes and begins to cause noticeable damage to leaves, stems, and buds, it’s time to act right away. The sooner you can deal with the infestation, the better chance you have of stopping the pests in their tracks and saving your plants from the point of no return.
Spray with Water
The safest and fastest way to control aphids is to spray them off your plants with a strong stream of water from the garden hose. Aphids are such small, soft-bodied insects that even a good rainstorm can knock them off. Once aphids are knocked off a plant, they rarely climb back on.
Insecticidal Soaps and Horticultural Oil
These controls are low-risk to people and the environment, but still need to be used according to their label instructions. They will kill aphids but must be applied on a regular basis in heavy infestations because aphids reproduce so quickly. Insecticidal soaps and horticultural oil only kill aphids that they come in contact with so plan to reapply frequently until the pests are completely gone. And don’t forget to spray the undersides of leaves as well as the top. Keep in mind that insecticidal soaps and horticultural oil will kill beneficial insects, too, so apply it carefully.
Crush Aphids With Your Fingers
If you aren’t the squeamish sort, and the infestation isn’t so heavy that it would take forever to clean off, gently rub your plants’ leaves and stems where you see aphids between your thumb and fingertips. Remember, these insects are very soft and delicate so they will easily get crushed with just light pressure. This tactic probably won’t completely eliminate every bug, but it will help enough that your plants will be able to grow healthy leaves again. Check back every few days to see if you need to repeat the procedure.
How to Prevent Aphids
Preventing aphids from setting up home in large numbers in your garden is possible. In addition to making sure your plants have the water, light, and nutrients they need for staying healthy, here are a few more ways to help keep aphid numbers down.
Use Row Covers in Your Vegetable Garden
In spring, protect young plants in your veggie plot with floating row covers. These row covers keep the aphids (and many other insect pests) out but allow air, light, and moisture to reach your plants. Remove the row covers when your seedlings are several inches tall or when the temperatures heat up in summer.
You may be watching your plants for aphids but these insects can also get a foothold in your garden by infesting weeds. Then it’s only a matter of time before they spread to your flowers and veggies, so make sure to keep up with weeding around these plants. Some weeds such as sowthistle and mustard appear to be especially attractive to these insects, too.
Attract Beneficial Insects That Eat Aphids
Plant flowers, such as marigolds, calendula, sunflower, daisy, alyssum, or dill nearby to attract beneficial insects that love to feed on aphids. Ladybugs and lacewings are especially effective at devouring them.