Hi Elaine,
I don't know anything about the Volck, like how often it's supposed to be applied, etc.
The only thing that rids/kills scale, burn roots, and non-chemical is Fish Emulsion. Elaine, I tried the old-fashioned way, using Rubbing Alcohol by rubbing the alcohol over leaves w/cotton balls and Q-Tips..I believe if a plant has few scale, RA helps, but when a plant is infested, something stronger needs to be used.
I learned about Fish Emulsion from a woman who owns a citrus nursery in Fl. They've been using it for yrs.
An Olive tree I ordered online was infested, minus the ants, but infested nonetheless. I didn't see the scale until it was too late. After the RA didn't work, I used 1 capful of FE per 16oz container of water. Shook sprayer. Then spray entire plant..Since FE is organic it will not burn roots, harm children or pets.
I use FE on plants before bringing them indoors for winter, too...it works as a preventative to scale, kills them, and a last foliar feeding.
BTW, it'll be 3 yrs this winter since my olive had the scale..I have to say, this summer I spotted a few on the olive again, gave it a spray, they're now history. Hopefully it'll be another 3 yrs before/if they return, but I think Olives are scale magnets.
You can find FE at nurseries, hardware stores, online nurseries or Ebay. Good luck, Toni
BTW, hosing helps to a degree, but those suckers tend to hand on for dear life. LOL

Toni....if you are going to recommend home remedies you should be more specific with measurements. 'Capfuls' might not be equal. Pour a capful out of your container and see if it equals a teaspoon, 1/2 tsp. or whatever. THEN, your good advice will truly be helpful!

Elaine, I think you'll need to be careful about the FE in the kind of heat you are having, too. It's the 'oil' in the FE that assists in scale control. There probably won't be anything regarding a warning about the heat on the label, either.

Your horticultural oils are considered one of the best methods of controlling and preventing scale insect outbreaks. Check your Volke label to see if it suggests a 'summer' rate of mixing. If you can't locate those directions, call the toll free number on the label, or purchase a 'super-fine', 'summer' oil.

Oils typically require more than one application to facilitate control. Remember, too, that scale insects can be dead but still present on your plant.

Luckily, horticultural oils are safe to use in regards to you, beneficial insects, pets, etc. That makes it a lot easier when you know you'll have to apply it several times a year.

Hi Rhizo..The caps are pretty standard size..and let's say a capful was a bit larger or smaller than standard size, I doubt it'd make much if any difference..Since FE is quite safe, a 1/4 teas more or less won't matter.

Elaine, since I've never measured the cap by teas, etc, I can't give an exact measurement..Sorry..but like I mentioned to Rhizo, either way won't effect the tree.
Now if I suggested a chemcial type product, that'd be a different story since too much could cause burn..Toni

Hire a professionsal. I had a 20 year old grapfruit and lemon infested in the yard of our new house. I have a guy come out and spray every year. Best $150 I spend every year.

what kind of scale are we talking about?

here is a very helpful link for many subjects on citrus especially in the central valley of California

Here is a link that might be useful: Citrus Entomology Homepage