i'm not sure if compost tea would do anthing for it????

May I assume you've seen the link below?

Have you tried all those suggestions, particularly 6., 7., and 8.?

Here is a link that might be useful: How to Control Scale Insects on Outdoor Plants

Although it smacks of "magic", since used coffee grounds [UCG] are considered almost an elixer for plant growth, I wonder if you pour boiling water over some UCG in bucket, and let it steep, and then drench the affected plant parts with the coffee...wonder what would happen? You might try it on one badly affected plant to experiment. I imagine you are about ready for moonlight rituals with drums and bonfires....well, maybe not THAT desperate.

I wonder what effect would be to 'paint' powdered milk 'paste' on the trunks/stems and let it dry? Would that seal off oxygen from the scale?

Hmmm...did a google search on key words "eradicating plant scales" and found several links that might prove helpful. Have you already tried the alcohol/dish soap solution spray/drench every other day
...
http://www.aos.org/AM/Template.cfm?Section=pests_and_diseases&TEMPLATE=/CM/ContentDisplay.cfm&CONTENTID=5671

Here is a link that might be useful: e-how -How to treat scales

emmgus,

It's unusual for one kind of pest to be on so many quite differnt plants.

Any chance of posting images of the scale on the various affected plants?

Is what you have really scale or might it be lichens, something many people mistake for scale and which is not at all harmful.

Your County Extension likely has the best IPM program to eliminate scale. I didn't see any mention of getting the crawlers so I suspect boning up on proper techniques for eliminating scale is in order. The Extension Office with the IPM program is the place to go.

Dan

Thanks for the responses. Sorry for the delay on my end, two days at home w/ one sick kid, a broken flute and an impending band concert for the other got me side tracked. :)

If moonlight rituals w/ drums and bonfires would work, I'd be all over it, I'm getting that desperate!

I am sure it's scale - cottony hydrangea scale as I was told my our extension office. I've looked it up countless times and there's no mistaking it. There's the sooty mold and nastiness to go along with it as well. I've definitely "boned up" on how to treat it, which is what I've been trying for close to four years now.

Part of the problem is that it loves my climbing hydrangeas, two of which are all the way up the back of our house. To make it worse, the many layers of peeling bark are a great place for the little buggers to hide and stay safe from the many rounds of spraying (soap and dormant oil) I have tried. A couple of times I thought I was making progress just to have them come back w/ a vengeance, as they are this year.

I need something that actually works, before this stuff destroys my whole garden. It's on all the hydrangeas, and has even decided it's not that fussy and I've found it on plants next to them. I did buy a systemic product, but have been afraid to pull the trigger, so to speak. (it's a soil drench type) I wanted to try one more time to see if there was some magic last thing that will work, but it really doesn't seem like it. I guess the best I can hope for is moral support.

Thanks for the responses. Sorry for the delay on my end, two days at home w/ one sick kid, a broken flute and an impending band concert for the other got me side tracked. :)

If moonlight rituals w/ drums and bonfires would work, I'd be all over it, I'm getting that desperate!

I am sure it's scale - cottony hydrangea scale as I was told my our extension office. I've looked it up countless times and there's no mistaking it. There's the sooty mold and nastiness to go along with it as well. I've definitely "boned up" on how to treat it, which is what I've been trying for close to four years now.

Part of the problem is that it loves my climbing hydrangeas, two of which are all the way up the back of our house. To make it worse, the many layers of peeling bark are a great place for the little buggers to hide and stay safe from the many rounds of spraying (soap and dormant oil) I have tried. A couple of times I thought I was making progress just to have them come back w/ a vengeance, as they are this year.

I need something that actually works, before this stuff destroys my whole garden. It's on all the hydrangeas, and has even decided it's not that fussy and I've found it on plants next to them. I did buy a systemic product, but have been afraid to pull the trigger, so to speak. (it's a soil drench type) I wanted to try one more time to see if there was some magic last thing that will work, but it really doesn't seem like it. I guess the best I can hope for is moral support.

The only thing I can find about control of any scale on any plant is the use of dormant oil sprays. Insecticidal Soaps are not generally of much use in controlling scales because the soap does not penetrate the covering. Dormant oils need to completely cover the scales to be effective.
The University of California - Davis does say a couple of the organophosphate pesticides (unacceptable to organic gardeners) can aid in suppressing these, but those pesticides also kill off the beneficial insects that can help control scales.

I came across this video about using vermicompost/castings in vineyard to control fungal infections, and thought of your problem.
While scale is different, I wonder if the VC would work for your problem?
http://www.youtube.com/watch?v=ATu-Ojar5rE

Here is a link that might be useful: VC in vineyard

can't ... resist ... any ... longer ...

I get depressed everytime I step on the scale too.

Sorry.

Seriously, though, a scale infestation on that scale is, well, kind of weird. Are the infested plants otherwise under some kind of environmental stress? Keep them otherwise healthy as possible (right light exposure, moisture and nutrient levels etc.) and really work the dormant oil after this growing season.

After four years of fighting this problem it is time to make a decision. What methods you presently are using do not work and the hydrangeas will die a slow death. You will have to remove them now or later as a severe cottony scale infestation is very difficult to control organically.

Suggest you get in touch with a licensed spray expert who has the power equipment to really blast the plants in early spring with a dormant oil spray. This would then be followed by a systemic treatment, properly applied into the soil. Timing is critical on both these applications. It may be that one systemic application and thereafter an annual dormant oil treatment may get you on top of the situation. Ask around at area nurseries, make calls from the yellow pages; find a spray expert with whom you feel comfortable. This will be an ongoing problem and you need the best person you can find.

When confronted with a problem such as this plaguing choice plants it is sometimes necessary to use chemicals. Of all the choices available, systemic applications are the better way to go as the chemical is applied directly to the root system into the soil and not sprayed wholesale into the air to drift on the wind.

What nandina said. Then use the UC Davis IPM site for future control.

Dan (go Aggies!)

Since the means of control provided by dormant oils is suffocation blasting the scale with a dormant oil would not be a good idea and could well result in severe damage to the plant. A gentle spray that fully coats the scale is what is needed not a high pressure application.

hey, what happened with your scale? This summer I found very large infestations on my hydrangeas, an extension agent suggested 'merit' pesticide, i haven't done it yet, did you come to any conclusion/resolution? ..

I also have it on my hydrangeas & evergreen plant. I don't know what to do. It is very depressing.