I'd examine the upper and lower surfaces of the leaves, too. Scale insect are a real challenge.

Definitely scale, also why are you pruning it? If you ever want to get fruit (will take 5+ years on a seed grown tree) pruning it will not help. Research node count.

I've had pretty good results removing scale insects by hand from trees that are small enough for me to reach the whole thing, which your tree is. I use a twig or pencil to just push them off. Make sure to do it fully when there's still a gooey live insect inside (yuck, but it works!) because if you wait too long, she will have produced her offspring already and dried up inside.

I found with our outdoors fruit trees in a diverse organic gardening environment, it doesn't seem to harm them much to have some scale insects, so I just try to remove the ones I can reach and leave the rest. They don't deface the fruit, though I guess they suck sap and weaken the tree a bit.

update. I removed all visable scale insects & applied horticulture oil to the whole tree in an attempt to reduce the spread of more suckers. in the last week I've watch the tree loose 90% of it;s leaves & I'm worried that it's going to die & I'm not even sure what I can do about it

Not to hijack the thread, but has anyone ever tried Neem as a systemic? There is some (but not a lot of) evidence that it can disrupt the life cycles of sucking insects if applied as a soil drench. I gave my trees battling scale some neem yesterday and an HO spray down, fingers crossed!

Oil tends to clog the pores on the leaves, killing them.

Oil, if it is a horticultural oil intended for use on plants, does not block plant leaves or kill the tree. HO applications are one of the main non-insecticidal recommendations made by authorities on citrus growing for dealing with scale infestations.

From the University of California at Riverside:

“A well-timed and thorough spray of horticultural (narrow-range) oil during the dormant season, or soon after scale crawlers are active in late winter to early summer, can provide good control of most species of scale. Certain scale problems on large plants and hosts especially sensitive to scale damage may warrant the application of a systemic insecticide.”

Dbarron, guesss are not facts.. Horticultural oils do not harm any part of a citrus tree, except when applied at temeratures above 90-F

Dont apply it during a sunny day either, apply in the evening or a cloudy day or HO will burn.