Soft scale continues to be a problem this year on many broad leaf evergreens, a few needled evergreens, and some deciduous shrubs and trees. Over the past couple of years it has been a mini epidemic.
To find soft scale, look at the branches and undersides of the leaves on suspect shrubs and trees for white cottony masses. They can be linear in appearance and one end is usually dark brown or black. It is often confused with mealybug.
Over time, soft scale will turn leaves yellow. Some leaves on the plant could be shiny and sticky from the honeydew that is excreted by the scale. The upper surfaces of many leaves will turn black from the sooty mold that will grow on the honeydew.
Soft scales cause the slow death of a plant as it takes a few seasons of infestation for the shrub to die from it.
At this time of the year, it is best to spray an all season horticultural oil to smother the scale. In mid summer, when the crawlers hatch and become active, spraying will probably be more effective as this is when the insect is the most vulnerable to treatment. Spraying can continue into the fall.
Another option is apply a granular or liquid systemic at the base of the plant in early spring. This should provide protection for the whole season.
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Soft Scale: "Dr. Z's" Tip of the Week
This entry was posted on June 12, 2015.