AusBonsai

Hi all,

I been getting alot of my maples getting hammered my Scale recently.
Been brushing/scraping them off constantly, and as recenlty started to use Pest Oil.
Id spray this on throughly but find they are still around.
I have applied 2 applications over several weeks so far.

Just wondering what other products are there to use.

Maybe a application that does not require brushing /scraping as i find this can cause damaging of important buds.
Also hard as there are still leaves on the trees and hard to get into the hidden areas.
Winter will be no problem but during the growing season is where i have issues.

maybe a systemic application, if so which particular brand has worked well?

thanks all.

Pest oil needs to cover each scale so you need to thoroughly cover every surface on the tree, including underside of each leaf. As you point out, that can be difficult to get consistent full coverage.
I can usually get good control with 3-4 applications over 6-8 weeks. Repeat applications allows for missing some surfaces each time but different application angles each application should give pretty good coverage overall.
Repeat applications are also necessary to catch any that have hatched since the last spray.
Maybe what you are seeing after the sprays are dead shells? I have found that any insecticide will kill the scale insect but the shell stays on the leaf or stem for many weeks after the bug is dead. You can check a few a week or so after spraying to see if they are alive or dead.

Systemics should be a last resort due to unintended collateral damage to beneficial insects like bees and wasps.
If you really need to go to systemics I've had good control of scale with Imacloprid based sprays though they are now hard to find because of the abovementioned collateral damage when used thoughtlessly. There are a number of different brands that are based on Imacloprid.

Thanks Shibui,

I will persist over the next few weeks of spraying and see how they go.

Also with Systemics, will they work in the winter when the tree is dormant? or is better when the tree is actively taking up water.

regards,

Also with Systemics, will they work in the winter when the tree is dormant? or is better when the tree is actively taking up water.

Great question. I'm not entirely sure but I assume the plant needs to take the chemical in through the roots or leaves in which case dormant would probably not work.

I also struggle with scale in Feb-March. Tridents seem to have no issues, but my Japanese maples barely survive the summer and Prunus don’t do much better. I think it’s one of our hedges seeding the infection to the whole yard, but even some plants in the front yard away from hedges are affected.

I too have had limited success with oils. I made up a spray on the weekend comprised of ~10ml dish soap, 200ml isopropyl alcohol and 800ml water. Will let you know if miracles occur.

It can turn out to be a battle on 2 fronts - you can have ants farming them. You may wipe out what is there only for a new batch to appear. If there are ants involved you will need to deal with them also. Ants are known to move aphids or scale insects from other trees.