Scale drench effect? #727331 - Ask Extension

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Scale drench effect? #727331

Asked September 27, 2020, 7:51 PM EDT

Found several leaves with white fuzzy black entities after the imidacloprid drench. Is this good, bad, indifferent, or wait-til-spring inconclusive?

Oakland County Michigan

Expert Response

Hello,
Please tell me what plant this leaf is from, and why you applied the soil drench.  That is, what insect were you trying to control on this plant?  
These may be wooly aphids.
Thank you
Laura Sheffer Replied September 28, 2020, 12:39 PM EDT
Leaf is from a saucer magnolia, trying to control the magnolia scale that had been dripping on our hostas that are under the tree.
The Question Asker Replied September 28, 2020, 3:11 PM EDT
Thank you. These do appear to be wooly aphids, and they were likely killed by the soil drench, depending on how long the drench has been in place. It takes several weeks for the plant to absorb the insecticide up into living leaves. 
Yes,wait until next spring and spot check the new leaf undersides. Another soil drench may be needed to completely control scale insects that feed on the twigs and branches. I see you have been provided with information on magnolia scale. 
Regards,
Laura
Laura Sheffer Replied September 28, 2020, 3:36 PM EDT

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