I Have China Girl Holly Shrubs That Have An Infestation…
Paul Asked
I have China Girl holly shrubs that have an infestation of scale and sooty mold. Can you advise how to treat this condition?
The Gardener’s Answer
Hello, Paul: Scale and sooty mold are a common problem among hollies. This is the time of year we notice the white insects on the underneath part of the foliage. At this stage these sap-sucking insects have hatched and are beginning to feed on our evergreens. There is only one generation per year, so controlling them now while they are active is essential in reducing the population for next season. A granular insecticidal systemic is effective; it works internally through the root system of the plant so it does take a bit longer to work than a foliar application. Spraying the holly with a horticultural oil is another option; the oil is used for hard-bodied scale and a soap can be effective on a soft-bodied scale although we typically see the hard scale species here in Kentucky. With a severe infestation it may be a good idea to use a combination of systemic and oil. The problem with the oil is that it is difficult to spray the underside of the foliage. As far as the sooty mold, this is caused from the scale; as they feed they secrete this sugary substance known as honeydew. It drops on the lower foliage and this is where the sooty mold grows. Aesthetically it is not very pleasing but it will not harm your plant. It can actually be wiped off if you have the patience to do so. Controlling the scale will control this fungus. As with any product always follow recommended application rates.
