Aphid Treatment for Junipers

Aphid treatment for junipers (Juniperus species) is helpful in ridding your juniper plants of pest infestations. During a particularly severe aphid problem, parts of your juniper plant or the entire plant may suffer the effects of aphid feeding. Always keep your juniper in the proper environment and provide appropriate maintenance for vigorous plants that can resist aphid infestation.

Preventive Treatment

The best preventive aphid treatment for junipers is proper environment and care for vigorous plants. Aphids often attack stressed plants or plants already in decline, so keeping your juniper healthy is key to avoiding infestation. Junipers thrive in full sun exposure and well-drained soil. These plants are sturdy and low maintenance with tolerance to droughts and heat. Only prune your junipers lightly as heavy pruning may damage your plant. Additionally, mulch the surrounding soil of younger junipers to prevent weed growth and to maintain cool soil, according to the Clemson University Extension.

Aphid Physical Characteristics

Juniper aphids are a large aphid variety that measure up to 1/5 inch in length, according to the Washington State University Extension. Displaying black bodies with long legs, these aphids are visible to the human eye due to their large size, making infestations easy to spot. In extreme infestations, your juniper may be covered with aphids.

Symptoms and Damage

Aphid infestations of junipers collect in colonies. They appear as dark groups on areas of plants. When aphids feed on junipers by parasitically sucking fluids from plant tissue, they produce honeydew, a sugary liquid that creates an ideal environment for the fungal infection called sooty mold. The presence of this dark mold is a secondary alert that your juniper has an aphid problem. Juniper foliage becomes brown during infestations and leaves, branches and twigs may die and early leaf drop may occur, according to the Washington State University Extension.

Natural Treatment

Before turning to chemical treatment options that may further harm your juniper or surrounding beneficial plants and insects, consider natural treatment. If you notice ants near your juniper, these may be "honeydew-feeding ants." Honeydew feeding ants feed on the honeydew produced by aphid infestations and the ant colonies protect aphids due to this relationship. Remove ant populations when present. For smaller infestations, physically remove and destroy aphids by hand or with a form of strong water pressure. Only use low-nitrogen fertilizer as aphids are attracted to the nitrogen in foliage that occurs due to high-nitrogen fertilizer use, according to the Washington State University Extension. Additionally, release natural predators such as parasitic wasps or lady beetles that hunt and kill aphids without damaging plants. Purchase these enemies through garden catalogs.

Chemical Treatment

If natural treatments are unsuccessful, turn to chemicals. Apply a pesticide for aphids as soon as they are visible or when you have decided that the infestation is too severe. Always avoid the active ingredient esfenvalerate as it kills bees which are a significant contributor to the Earth's ecosystem, particularly plant life. As long as your juniper measures less than 10 feet in height, you may apply the pesticide on your own; if your juniper exceeds 10 feet, contact a professional. Cover all foliage with one application of pesticide; pesticides kill aphids during treatment. Apply an aphid pesticide with one of the following active ingredients in the evening when bees are at rest: cyfluthrin, acephate, fenbutatin-oxide or bifenthrin, according to the Washington State University Extension.