How To Control And Kill Aphids On Plants In Landscapes And Gardens

Infestations of Aphids can cause some serious damage to plants in our landscape and gardens. As you can see in the photo above, Aphids are small, hard-to-see insects that hide underneath leaves. 

Aphids cause damage by sucking the juice (chlorophyll) from their host plants. Over time, their damage causes the leaves to yellow and eventually drop from the plant. They can also cause fruits, vegetables, and flower buds to prematurely drop off. In a bad infestation, their waxy excretions (also known as honeydew) encourages the development of sooty mold fungus.

If you see aphids on your plants, there are several control options:

Wash them away. Aphids can be dislodged with a steady stream of water. Repeat the treatment as necessary. This is best for light infestations.

Neem oil for outdoor plants. Neem oil is an organic oil derived from the neem tree. Use according to label instructions. In addition to its insecticidal properties, neem is also a fungicide and has systemic benefits (meaning the plant absorbs it so it can control insects it doesn't directly contact). According to the Environmental Protection Association, neem is safe for use on vegetables and food plants as well as ornamentals. 

Note: To avoid harming beneficial pollinating insects, I recommend spraying any insecticide in the early morning or late evening hours when beneficial pollinating insects are not active.

Insecticidal soap for indoor houseplants. Insecticidal soaps are available in the marketplace, or you can make your own by using a dish detergent such as Ivory Liquid. Try to find a product free of perfumes and additives that might harm plants. Mix the soap in a weak concentration with water (starting at 1 teaspoon per gallon and increasing as necessary). Spray on plants.