Calico Scale

Eulecanium cerasorum

Calico scale, Eulecanium cerasorum is a soft scale insect that attacks a large variety of woody plants. Calico scales produce large amounts of honeydew in the spring which can coat tree leaves, branches, sidewalks, and cars. This sticky sap soon turns black from sooty mold fungi growing on it and – in severe cases – may interfere with the tree’s ability to photosynthesize, making it more susceptible to woodborers, drought, and other stresses.

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Treatment Strategy

Calico scale is most effectively treated with soil applied products such as Optrol™ and Transtect. These systemic products are applied to the soil at the base of the tree and are taken up by the root system, working to control insects from the inside of the tree. A contact insecticide such as Up Star Gold can be sprayed on the scales, but this is rarely used as the timing must coincide with crawler emergence, which only takes place for one week during the year.

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Calico Scale Treatment Option 1

Transtect is applied to the soil and will provide a quick knockdown (within 2 weeks). It has a residual of at least 90 days, and should be applied in the spring.

Application Type Soil drench

DIY Product/Equipment Needed:

• Transtect

Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Calico Scale Treatment Option 2

Optrol™ is applied to the soil and has a long residual (1 year), however, it usually will take 30 – 60 days for the product to reach the leaves. Professional arborists often apply Xytect™ in the fall of the year for control the entire next season. Early spring applications are also very effective.

Application Type Soil drench

DIY Product/Equipment Needed:

Optrol™

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Calico Scale Treatment Option 3

Spray products such as Up Star Gold are not used very often for larger trees due to issues with drift and contact with beneficial insects. They are, however, still used on smaller plants that are easily treated with a hand sprayer. These products typically have a residual of 10 – 14 days and should be applied to coincide with egg hatch and crawler emergence to be effective. The hard shell of the adult scale protects the insect from sprays, so monitor your tree to determine when to spray.

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

Calico Scale DIY Kit

Option 1

Application Type Soil drench

DIY Product/Equipment Needed:

• Transtect

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Option 2

Application Type Soil drench

DIY Product/Equipment Needed:

Optrol™

• Soil Drench Kit

• Measuring or diameter tape

• Bucket or watering can

• Gloves

Option 3

Application Type Foliar spray

DIY Product/Equipment Needed:

• Up-Star Gold

• Hand pump sprayer with wand

• Gloves

• Safety glasses

How Is It Spread?

Calico scale has one generation per year. Hatching in the late spring, crawlers move to the leaves where they settle and feed for the summer. In late summer they move back to woody tissue where they molt and create a hard waxy coating. In very early spring overwintering crawlers lay their eggs.

Susceptible Trees

Calico scale can be a pest to all stone fruit and ornamental fruit trees, elm, maple, zelkova, honeylocust, sweetgum, magnolia, pyracantha, dogwood, buckeye, boston ivy, and tuliptree.

Symptoms

• Large amounts of honeydew in the spring.

• Sooty mold fungi growing on the honeydew.

• Stunted, yellowing leaves leading to premature leaf drop and dieback.

Lookalikes

None

Related/Similar Problems

None

Timing

Spring or fall

Urgency

Moderate

Risk of Spreading

Moderate

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