These evergreen shrubs have been doing well for years and then this white residue has just appeared. It seems to spread kind of fast. What should I do?
There isn't enough info here for us to try and help you.*
Do you know the name of the shrubs?*
Do you have any pictures you can post?
Where in the world do these shrubs grow?
If you can't post pictures and don't know the name of the shrubs, let us know if these are needled evergreens like a pine tree or if they are broad leafed like a Rhododendron.*
Also tell us if the residue is on the leaves/needles or on the branches.* If it's on the leaves, is it fluffy like cotton or does it look like someone spilled milk on them?
Here is some more info. They grow slowly in Mt. Clemens MI. 30 miles *North* of Detroit . They have needles. The white residue is like white paint that is making the needles more* white*. My guess is they are Mugo Pine. They are about 3'feet in diameter and about 1 to 2 foot high. If you really need a photo , I will have one Sunday. Thank-you .
Edward, sorry it's taken so long to get back to you.* I suspect pine needle scale.* Take a look here to see if this is what you are seeing.
If that is what you have, fall is a good time to treat for this.* I would recommend a horticultural oil.* I prefer an organic such as Organocide which is made from sesame seeds.* There is another called Organicide made from petroleum that I do NOT recommend.* Insecticidal soap sprayed every 5 to 7 days until they are gone is another option.* You can even make your own.
Please let me know if that is what you see.