My small Juniper has a serious scale infestation. I'm thinking of covering the pot and trunk in plastic wrap, suspending the plant upside down in a cooler, submerging it to within about an inch of the wrapped soil. Would this work to kill scale and if so, how long would I need to keep the foliage submerged?
Thanks!

Pease pay attention:

To effectively kill scale, the water where the juniper will be submerged needs to be mixed with some kind of oil, like Need Oil.
Which is bad news, as junipers and pines don't like to be covered in oil.
This is a real warning; following this "technique" I have killed a very special (and big) cork bark black pine.
Yes, I got rid of the scale.
But the tree didn't survive the treatment. First sun out the needles got droopy, yellow and died.

Yikes, I hoped just the lack of oxygen for a period of time in regular water would safely do the trick. Thanks.

KentMYork wrote: My small Juniper has a serious scale infestation. I'm thinking of covering the pot and trunk in plastic wrap, suspending the plant upside down in a cooler, submerging it to within about an inch of the wrapped soil.

This will stress and weaken the plant. Also, you will not know if it worked as the scales will stay on the plant.

I have had very mild infections (just a few on a plant) and I remove 'm mechanically (and check regularly to see if they return).
There are more methods, but these can easily be found using Google.