How to Control Mites & Scales on Juniper

Mite or scale damage can affect healthy juniper branches like this one.

Because junipers come in a wide variety of shapes, sizes and colors, they decorate many landscapes across the United States. Although resistant varieties are increasing, many older varieties succumb to various pests and diseases. Both juniper scale and spider mites can cause significant damage to your junipers. Juniper scale may cause uneven growth or stunted twigs. For spider mites, it's best to know how big of a population you're dealing with before selecting treatment. Both pests succumb to various types of pesticides, although horticultural oil and insecticidal soaps seem to do the trick more effectively and with less dangerous chemicals.

Things You'll Need

• White paper
• Insecticidal soap
• Horticultural oil

Instructions

Mites

1. Hold a piece of white paper under a potentially mite-infested branch of your juniper and give the branch a firm hit.

2. Examine the paper while holding it horizontally to check for signs of mites. You will see mites crawling around on the white paper. If there are several mites per branch hit, the problem is serious. If there are not many mites per hit, cultural control is ideal.

3. Spray your juniper with a strong spray of water from your garden hose. This will dislodge the pests from their roosts. Don't do this during freezing temperatures; early and mid-spring are ideal seasons for this method because mites are cool season pests.

4. Apply insecticidal soap to your juniper according to manufacturer's instructions if there are several mites present per hit during the paper test and if spraying with the hose didn't manage the problem. Apply in the late winter or early spring when spruce spider mites are active.

5. Clean up any fallen needles under your juniper, particularly after the strong spray of water. Burn the needles.

Scale

1. Check for signs of scale insects on your juniper. Scale insects are small, up to 1mm. Symptoms include off-colored and stunted branches. Honeydew, a shiny, sticky substance, is often found on infested junipers.

2. Apply horticultural oil to the juniper in late winter or early spring to suffocate adult females and stop the life cycle.

3. Apply acephate, malthion or carbaryl to the juniper if crawlers (nymphs) are present. Do not apply carbaryl if spider mites are present as well; carbaryl can stimulate the spider mites' reproduction.

References

• Clemson Cooperative Extension; Juniper Diseases and Insect Pests; Nancy Doubrava, et al.; December 2005
• North Carolina Cooperative Extension Service; Juniper Insect Pests; J.R. Baker, et al.; July 1996