Amy, is there any way you can send us some images? Let's make sure that you do have a scale infestation and lets see the condition of this tree.

Rhizo, I'd love to but right now brains not working well. I forget how to get on bank acct or email half the time. It should improve....

amy

same answer in your miss kim post

you have to hit the crawlers with the spray ...

and another plant .. that if it is truly scale.. you could cut to the ground and let it regenerate ....

hey rhiz .. am i confusing horticultural oils and dormant oils??? .. if so.. i will differ to your glory and knowledge.. lol .... set me straight ...

ken

Here is a link that might be useful: link

Ha, I'm going to have to tell my husband that one!

The term 'horticultural oil' is used to mean all of the different types of oils that are used to control pest problems on plants. Dormant oil is one, so is Neem oil, so are summer oils, etc. In the past, all oils were known as dormant oils because that's pretty much when they were used, and only on deciduous plants. Times and technology has changed.

So, I'm really being lazy when I use that term, and what I should probably do is be more specific as to what category of horticultural oil. Most of them can be used from season to season, however. I always keep Neem oil and a dormant oil on hand. The dormant oil can be mixed at a different rate to make it suitable to spray on the foliage of plants pretty much all growing season.

Here is a link that might be useful: What the heck are Horticultural Oils?

I think the willow was different. It looked like nectria canker, coral spot. IT was covered, absolutely covered, and the areas did look coralish. I've looked through diseases in my plant books so much, the bindings coming apart. I looked at it further, too tired to spray for naught. There was canker issues. I pruned some out, The bark down further on some branches (inside bark) was black. I gave up, another of 3 trees dead today. IT was a $6 thing years back, I shouldn't be sad. During construction and stuff heavy stuff was laid on roots (not that that would cause).. I probably pruned wrong in past. Soil was eroding, and too mushy right now...

Lilac, I did spray, but am not too optimistic.. I dug around the roots abit.. nothing odd. But these things, if I scratch them off, the bark comes too so then there's the cambian (green). And they too look, odd. There's much more and base but there's not a twig uncovered.

When small retaining wall was being rebuilt there this summmer, the stupid boy (the smart boy worked out front),did all kinds of odd things. a lot of this lilacs roots were cut and left hanging out. Then he accidently broked some stones (claimed they were old) so the rebuilt wall is about 8" lower than previous. That means all winter erosion, more of the lilacs feeder roots got exposed. I tried to prune a few yucky branches but couldn't find my good pruners (what else is new) and gave up for day.
Also, odd horizonal very light marks across many of lilacs thicker branches, but not completely circling and not really breaking through the bark..

Found my 7-son has/had borers, some girdling root issues, korean spice rabbits have been girdling, a few others ... dwarf blue spruce rotted (my fault)... more..

Amy

but rhiz ...

am i right in thinking that momma is dead.. with eggs below.. and will a dormant oil do anything.. prior to the crawler coming from under????

it would seem useless to spray ... if dead momma is impervious ...

or does one oil permeate her carcass ..???

amy .... i really wish you could get some pix.. because i am having a hard time with so many stories of death and destruction in ONE GARDEN .... the odds of all these problems seems infinite to me ... we want to help.. but it gets hard speculating .... but we will .. keep posting..

good luck
ken

Ken...you have part of the information. Most scale species can be found in all stages (egg, nymph (crawlers), and adults) at any given time. Even overwintering. That's because scale can reproduce sexually and/or parthenogenetically. Female scales of many species are known to overwinter.

Horticultural oils can be effective in smothering even the adults, as well as the eggs and nymphs.

aw come on rhiz ..

if momma is dead.. and providing an impermeable covering... will the dormant oil permeate her dead body.. and kill the eggs underneath ...

i really want to get to this answer.. and somehow you keep dancing around it ... unintentionally i am sure ....

ken

YES, the oil can smother the eggs under the covering. However! Most scale species don't die before winter...some do but not most.

And scale 'shells' are not impermeable. If they were, the insects couldn't breathe. Scale have abdominal spiracles just like other insects. That's what gets blocked by oils and causes them to suffocate.

thank you

so is it important to actually ID the scale??

ken

ken, if one is spraying dormant oil, it's not necessary to ID the specific species of scale.

gonna have to take a minute to pop my shoulder back into it's proper position

Amy, there is no way your lilac has scale. If you peel off the "scale" and you are peeling bark and seeing cambium, you have misdiagnosed the lenticel. Scale should be able to removed without taking off the bark.