What can I soak a sick plant in for serious scale?
 

I have a small cymbidium which I am quite keen to rescue but it keeps getting worse. It has an extremely bad scale infestation which has got right into all the gaps between the leaves. I have manually removed a lot of them and been spraying it with a pesticide to try to get rid of them but to no avail. The plant has continued to decline.

Is there anything else that I could soak the whole plant in that might help? Is it worth soaking it in peroxide or something like that?

Try the dry ice method that I posted about a couple of months ago; there is some criticism about the drop in temperature. If you do the method correctly, the temp drop will not be that drastic. Just remember to put the container of water and dry ice on a trivet of some sort to keep it from chilling the receptacle. If it does get cool, just remove the container/fog maker and 'pour' the CO2 fog in until all the air is gone. Once you put the top on you can sit it in the (indirect) sun or another warm place to bring the temp up a little if needed, but I never have needed to do so.
This method will smother all oxygen breathing organisms and will give a boost to the plant. This is very good for scale and mealies as it get's down in the cracks.
You can get dry ice here at Walmart or at an ice cream shop. Hope this helps!
Steve:waving

Haven't needed to try this myself (hard to type with crossed fingers) but wanted to add another source for dry ice. Party and catering supply stores.

Hmmm...we have none of those types of stores around here. I live in a regional town with a small supermarket, a fishing shop and a couple of takeaway joints and a post office LOL. Any other suggestions? If I need to get anything special I'll probably need to order online.

I've only had a modest scale infestation on a dwarf citrus tree. I just spray the cinnamon concoction. I don't know if it would work with all the nooks and crannies that cyms have.

---------- Post added at 02:16 AM ---------- Previous post was at 02:13 AM ----------

How about predators? I have no clue what they may be, though. LoL

What is wrong with some insecticide? Anything with Merit (look at Bayer Advanced products) will work. Y'all have a way of making this an unnecessary adventure. If you can't find Merit (unlikely since it's everywhere), darn near any insecticide will work.

That's what I am already doing but I just can't seem to get rid of them. I've had it since christmas and have been spraying it weekly with insecticide and it's just getting worse :(

---------- Post added at 09:31 PM ---------- Previous post was at 09:30 PM ----------

What's the cinnamon thing anonymouse?

What insecticide are you using? Weekly is not frequent enough to catch the new hatches. The insecticide won't kill eggs so you need to kill any new insects before they provide new eggs.

How are you doing it? You need to spray to runoff, be sure to remove and saturate all covering bract areas, and drench media.

The reason I suggested Dry Ice, is that it will get in ANY crook and cranny as it is taking the breathable air away -also it leaves no residue and is safe for anything not in the treatment container. But if you don't have access to such, I understand. You may check with your grocer - he may have a source of DI. Otherwise it's chemicals or other treatments. You could put it in a bag of ladybugs or other carnivorous insects maybe, but I am not sure what carnivorous bug is in Australia!
Sorry to get your hopes up!
Steve:waving

I admire your imagination and certainly creatures who breathe oxygen will die in atmospheres rich in carbon dioxide. Typically the air must be displaced by about 50% CO2 and thus reduce the oxygen concentration to about 10-11%. I'm sure that varies with the creature.

Here's the problems....first how do rig up something to allow the CO2 to displace the air? Second CO2 sublimes at -109.3 degrees F. The vapor is at that temp as it leaves the solid surface. Certainly it warms quickly and if you give it a distance to travel it will reach a reasonable temp, but just putting it in (for example) an open bag under the plant will surely be a problem. Third, it has no residual effect and will not kill eggs so you will have do it repeatedly at short intervals. Given that you can't store it that means a car trip for each treatment.

In my view that's what I refer to as a hell of a lot of trouble just to be cute and do something unique. A spray bottle of insecticide frequently applied looks like a much better plan to me. But then I have approximately 2500 orchids so I don't have time for playing around with CO2 games.

Those of you who want to mess with CO2 remember it is approximately 1.5 times heavier than air so think about how you should orient a container allowing it to displace the air. It's too much trouble and results are going to be unreliable based on your setup and not be residual.🐛