Dayton: Liquid Sevin is pretty effective for both scale and mealies, at
recommended label rates. Mavrik (mentioned in another post) didn't seem to
do much, around here. Cygon (if it's still around) will work, but does
cause a lot of malformations, in my experience. For anything else that I
know of, you'll have to read labels and make your own judgments about
mixing. Orthene WP 75 (the 75 being the percentage of active ingredient)
was my fav for many years. It worked _very_ well, but is no longer
available around here. The active ingredient was acephate. The Orthene
Fire Ant powders still out there are pretty much the same thing, except that
the active ingredient is reduced (and I'm told it's illegal, at least in the
US, to mix stronger, so as to get back to the 75%).

The Sevin and acephate, if properly applied (all over the plant, including
lower leaf surfaces) DO work in bark and other "chunky" mixes, but it does
take time. If you go with an acephate product or the Liquid Sevin, you need
to spray once a week for 3 weeks. [I _wish_ I had a 1-time cure ...].
Otherwise, the pests will recur, and be more resistant the next time around.

To the extent possible (which I know depends on the number of plants at
issue), the toothbrush (also previously mentioned by another poster) along
with alcohol, soap or oil (if your conditions are not too hot for the
latter), is also a very good idea. At minimum, it will get rid of the dead
pests so you don't have to keep checking the same areas for re-infestation.
It also provides a faster "knockdown" than you can get with any systemic I
know of.

Seriously-infested plants will also benefit from repotting, for which the
major season is approaching. Hope this helps, Kenni

"Dayton" wrote in message
...
Does anyone have experience, hopefully positive, using systemics on
orchids? I am at my wit's end spraying Neem and insecticidal soaps for
scale. Now mealies are beginning to show up as well. Getting very close to
making a large trip to the compost heap (if the snow ever melts) and going
back to ferns and begonias.
Most of the problem children are phals potted in either soil-less mixes or
moss. I suspect no systemic would work in a bark mix.
I have a fairly old (20+ years) can of DiSyston granules(Disulfoton
Diethyl ethyl phosphordithicate) that I've used on other soil based plants
with some success. Cannot find any indication of use for orchids and there
isn't much on the web. From what I've found, it may even be banned in some
places. Not sure what else may be available, but I'm hoping something
works.
Appreciate any input anyone has.