Scale and oils - frequency? How to tell if effective?
OK, apologies in advance -- yet one more round on scale... I have an older (say 6 yrs) Meyer in a 24 gal pot outside that has a nasty infestation of red scale (had it when I moved in). Its so bad that the things have been fighting for room on the older gnarly grey branches (where I can't see 'em) as well as leaves and young green branches. I've only got about 15 leaves left and half of them look far too yellow.
I tried the famous canola and Volck mixture posted here about a month ago. Unfortunately, I still have oodles of scale and I have three questions:
1) how can I tell if a scale bug is a dead bug or a live bug? They all look the same to me except for size and none of them seem to squish more than others. Do they fall off when they're dead? (I sound like my 4-year-old nephew... but....)
2) How frequently can I repeat the oil spraying? Its pretty clear to me that I've got plenty of live ones (leaves I know I had scraped clean now have 'em again) and I've been scraping 'em off with my fingers but 'tis not getting them nearly enough.
3. Once they've armored up and attached can they move around if you knock them off or are they history once they come unattached? I squash most of them, but I know some are just falling off into the container.
Thanks for your collective wisdom!