Insecticides for Magnolia Trees

• Magnolia tree flowers Jupiterimages/liquidlibrary/Getty Images

  Home gardeners are at risk of losing the visual impact and sometimes-sweet fragrance of their magnolia trees when pest infestations become severe. Insecticides offer reliable control against pests of the magnolia tree, particularly when used in conjunction with consistent maintenance for vigorous trees. Grow magnolias in full sunlight to partial shade, as well as in well-drained soil rich in nutrients with an acid pH of 5.0 to 6.5.

Imidacloprid

• Imidacloprid is a systemic insecticide well suited for use on magnolia trees. Systemic insecticides are taken up within the internal, vascular system of magnolia trees where they can reach bugs that feed or hide beneath plant surfaces. Belonging to the chloronicotinyl class of insecticides, imidacloprid disrupts the reception of nerve impulses to the brain, resulting in death. Imidacloprid is appropriate for use on sucking bugs such as aphids, whiteflies and thrips.

Horticultural Oil

• Horticultural oil is a low-toxicity insecticide for use on magnolia trees. This type of insecticide needs to saturate plant parts, as it kills bugs such as scales and aphids on contact. Horticultural oil may need to be reapplied, as it provides no residual control. Applications in intervals of one week to 10 days while pests are in their active feeding stage are reliable. Horticultural oil is a mineral oil produced as a residual product of refined petroleum, according to the Texas Agricultural Extension Service. These types of insecticides work by saturating and suffocating insects, and by removing the waxy coverings that protect them.

Malathion

• Malathion is an insecticide appropriate for use on magnolia trees. Belonging to the organophosphate class of insecticides, malathion is a foliar spray that controls bugs such as aphids, leafminers, caterpillars, mealybugs, scales, whiteflies and thrips. Organophosphates inhibit normal nerve functioning within insects, leading to death. Formulated for use on deciduous and ornamental trees, malathion is well suited for use on magnolia scale pests, according to the Texas Agricultural Extension Service. Malathion is a non-systemic insecticide, meaning it is not taken up within the internal systems of the plant.