I would pick up some horticultural oil or a pre-mixed spray bottle of the same and use it: it is an excellent control for scale, and has very little effect on good insects in the environment. I use a product marketed under the Master Nursery name, but there are many that will work (Bionide, for example). Mine lists on the label that it can be used on fruit trees, vegetables, houseplants, and ornamentals "up to the day of harvest." Oh, yes, I should mention that the spray I use is odorless, as far as I can tell.

You may have to apply it twice, at an interval of two weeks to get the scale insects completely under control, but I find that when their numbers are not huge one application in the winter is enough to get you through to the spring when the rain and humidity keep the insects in check.

I used horticultural oil to spray three of my citrus trees just last week on a day when the temperatures were barely above freezing with no problems. The trees were outside for about 5 minutes each.

Before you spray, make sure the trees have been nicely watered. Three more suggestions: 1) where the scales are thickest, just running your finger or a tooth-pick over them with just a bit of pressure will do a lot of damage to the larger scale insects, making the oil spray's task easier (you won't get the nymphs, which are much smaller and mobile, this way, so on its own rubbing out the adults won't get ride of the problem); 2) if it is really cold (below 40 degrees F) once you have sprayed them, bring them inside after a few minutes of dripping and let them drip dry on old newspaper spread on the floor--I do this on the unheated back porch which is nicely warmed by the sun; 3) make sure you spray the entire tree including the trunk and the underside of the leaves--I even spray the bark mulch in the containers, figuring some nymphs may be wandering around on it.

I use Fish Emulsion. Or should say used.
Got an Olive Tree infested with scale. Didn't see these disgusting bugs at first, so placed the tree between two citrus.
It was while misting I noticed the poor Olive had brown lumps everywhere, and the two neighboring citrus branches closest to the Olive, were jam-packed.

I remembered a woman who owns a citrus nursery in Fl told me they used Fish Emulsion and water as a preventative and insecticide.
I phoned her, got directions and applied.

The following day Scale were goners. Although I didn't see any other scale, I applied a second application. This happened over 5-yrs ago.
Thankfully, I still spray with FE, as a preventative, never saw nor dwelt w/those bugs again.

The only con is FE has a fishy odor that lasts 2-3 days. There's an odorless type, but I've never tried it, so don't know if it has a smell or not.
The pro is it kills and prevents scale and mites from attacking plants. And it's organic, no chemicals.
Good luck, Toni

I too use FE. recently I had a case of red mites and a couple of applications takes care of it. The smell is quite powerful at first but does go away pretty quick.

Just to emphasize don's suggestion of the horticultural oil...there are many options to select from that will work very well and many are pretty odorless. Oils continue to be the very best method we have of scale control; that's the reason why the fish emulsion works, by the way.

When using any oil product, be sure to read and follow the directions carefully as there are temperature restrictions. Never mix more than the label suggests and don't apply more frequently than directed.

You won't find directions on the fish emulsion so the amount would be a guess. But the temperature restrictions would apply.

Thanks so much for all the advice. I don't know if I can get Master Nursery around here but I've definitely seen Bionide products. Hopefully it'll be warm enough today that I can take the trees outside and get this taken care of.

Could scale contribute to the tree dropping fruit, or would that likely be caused by levels of sun, light, water, etc?

Thanks again!

I am not sure they are the cause of fruit drop, but can suck sap from the tree and cause the leaves to turn yellow and drop.

That is a good question, since sometimes the obvious may not always be that way with different insects. Like I suppose fruit would drop if the leaves do, but then again a bug expert will helps us know for sure on this one.

Good luck

Mike

I had the same problem last year. This year I sprayed with a homemade oil (a mix of vegetable oil about 1/4 cup, soap 1 T, and fill up a spray bottle with water). It's cheap, easy to make, and no aphids or scale so far this year!