mites on a hemlock??

[KWolt]

I don’t know if anyone else has seen this but I’ve seen scale much worse on hemlocks that have been sheared. I’ve also seen this on other plants that have been sheared and their own insect issues. I don’t know if the plants are stressed from the shearing and makes them more susceptible to insect attack, does the dense foliage from shearing afford some protection from harsh weather or predator control of the problem insect? KT, can you comment on this?

 

[jed1124]

In the last 5 years I’ve seen more Elongate Hemlock scale regardless of what’s been done to the trees. That being said, sheared trees are certainly under more stress than a naturally growing tree.
Another thing to consider is that a property that is more manicured is more likely to have other things going on like lawn treatments, tick sprays, or mosquitoe sprays. Lots of opportunities for beneficial insects to get wiped out.

 

[KWolt]

As a matter of fact, I saw bad mealy bug on sheared hollies on a property where the shrubs had been sprayed for years (by a prominent tree care company) and the hollies next door, not sheared or sprayed, were fine. They had a different exposure to wind and salt air but obviously the shearing and spraying didn’t do the infested hollies any good.

 

[JD3000]

Nitrogen applications may also play a role

 

[KWolt]

Once I started thinning the hollies into a more natural growth habit and the spraying stopped the mealy bug issue subsided.

 

[JD3000]

Mealy bugs have a protective waxy layer when mature so sprays often have no impact on them. Predators and parasites would not be so lucky however.