Don’t let those little white or brown specks on your shrubs and trees fool you, as they are actually insects called scale, and, if left uncontrolled, they can damage or even kill certain shrubs and trees. Plants such as Euonymus, Juniper, Crepe Myrtle, Maples, and others are susceptible to scale problems, with damage caused by the insects sucking the juices out of plant leaves and stems. They are very small like other insect pests with “piecing-sucking” mouthparts, such as Aphids, Lacebugs, and Mites to name a few. But don’t let their small size fool you, as, with great numbers, they can literally suck the life out of certain shrubs and trees.
There are two types of scales, armored and soft scales. Armored scales such as Euonymus Scale have a hard shell over their body, and appear like small disk like dots on stems and leaves. They appear stationary, and don’t really look like insects at all. They have several generations per season, compared to soft scales which just have one generation per year. Colors are usually white, tan, or brown. Soft scales produce honeydew which attracts other insects such as ants and lead to black sooty mold. Both types of scales can reduce plant vigor and health, but armored scales can harm the plant to the point of death if left unchecked.
Mid to late Winter is a great time to apply dormant oil or horticulture oils to plants, which basically coats the stems and leaves suffocating the small scale insects. It’s best to apply when temperatures are cool to warm, well above freezing temperatures, and before it becomes too hot later in April. Horticulture oil is often referred to as dormant oil because it’s applied now when the plants are dormant. This is a very safe means of control, without the application of contact insecticides which could affect beneficial insects. At LawnAmerica, we add a good systemic insecticide named Safari to the mix, which is absorbed by the plants and root system, and provides months of control into spring and summer as insects attempt to feed on plants.
This dormant oil/systemic insecticide treatment also works well for other insects which feed on plants during the season either by sucking plant juices or by chewing. So we also apply this to plants such as Azaleas early in the season to control Lacebugs, and to other plants which are susceptible to insects feeding during spring and summer. If you have Euonymus in your landscape, it’s almost certain that you will have scale problems, so we recommend that you treat now with dormant oil to help prevent these.