Scouting for Scale


Sooty Mold

Winter Solstice, the first day of winter seems like an unusual time to be outside looking for insects.

winter

However, it is an excellent time to scout for both Soft Scale and Armored Scale. With the leaves off trees and shrubs, it is easy to find plants with signs of scale damage and scale.

Sooty Mold 1

As you are scouting in the nursery or landscape, plants that just do not look right can be an indicator of scale. Late summer, one of our growers noticed early fall color on Red Maples.

red maple

At closer inspections, an infestation of oyster shell scale was found.

oyster shell scale on maple

Upon returning last week, the same infested trees are retaining their desiccated leaves.

desiccated leaves

The oyster shell scale is much easier to see when the trees shed their leaves.

oyster shell scale trunk

Pine needle scale could be seen on Japanese Black Pine, Pinus thunbergi,

japanese blk w scale

as well as Scotch Pine, Pinus sylvestris,

scotch scale

and Austrian Pine, Pinus nigra.

pinus nigra

In addition, Hemlock elongate scale was seen on Canadian Hemlock, Tsuga canadensis.

hemlock scale

In addition, Juniper Scale on Juniper was observed.

juniper scale

Since Pine, Hemlock Elongate and Oyster Shell Scale are all Armored Scale, they produce no honeydew.

Magnolia Scale

mag scale

and Fletcher scale are soft scale and produce honeydew, which causes sooty mold. Sooty mold is very easy to see in the winter since the foliage is gone.

blk soot

By looking up or in on the plant, you can inspect for scale. Magnolia trunks and stems will appear black when infested.

blk stem

The interior of Japanese yes may appear black as well.

blk yew

At closer inspection, the scale could be observed.

fletcher scale

Euonymus scale was easy to see in these top grafted plants.

euonymus scale

euonymus top graft

The message is now is a great time to scout for scale. Based on label recommendations, dormant oil can be effective in reducing numbers of scale. The key is to document the plant and type of scale, the location of the plants, and investigate when crawlers emerge and plan to spray at the appropriate time and interval.

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