Treatments for Gardenia Wax Scales

About Japanese Wax Scale

• Japanese wax scale doesn't look like a typical insect, but often is mistaken for a natural part of the plant. The insects are small and have no visible legs, although male insects have small wings. The waxy white or brownish blobs the pests excrete is quite noticeable, however, as is the damage caused when the insects suck the juice from the gardenia plant. Severe infestations of scale stunt the growth of blooms and foliage. Eventually, the leaves turn yellow and drop from the plant.

Cultural Control

• Healthy gardenias are less susceptible to damage caused by scale. Ample water is especially important, especially during warm, dry weather. Gardenias benefit from even soil moisture, as frequent fluctuations of soggy soil and dry soil stress the plant. A 2-inch layer of mulch helps keep the soil evenly moist. Two or three regular applications of fertilizer -- in early spring, late spring and autumn -- keep gardenias strong and vibrant.

Biological Control

• Often, scraping the scale from the branches and leaves is enough to keep a light infestation of scale at bay. If the infestation worsens, natural controls such as lacewings and ladybug beetles feed on the scale, keeping it under control. Parasitic wasps are especially effective, as the wasps lay eggs on or near the scale. The larvae then feed on the scale. You can often tell if wasps are feeding on the scale because the scale turns brownish in color. Although biological controls are effective, they often take several months to reduce a heavy population of scale.

Non-Toxic Control

• If the scale infestation is severe and you don't want to wait for biological controls to take effect, insecticidal soaps are an effective, although short-term control. Insecticidal soaps are beneficial because they don't kill lacewings, ladybug beetles, parasitic wasps and other beneficial insects. Before using insecticidal soap, read the label on the container to ensure the substance is safe for gardenias. Apply insecticidal soaps regularly -- usually about every 10 days, or as directed on the label.

Chemical Control

• Chemical controls should be used with great care, and only when other techniques don't work, as insecticides kill not only scale, but beneficial insects that prey on scale. Apply insecticides strictly according to the directions on the container. Some insecticides can be watered into the soil, which prevents spray drift.