A lot of the pesticides have both systemic and contact prosperities.
Although Mal and Sevin are basically used for their contact kills, both have
weak systemic prosperities. Orthene is most commonly used as a systemic but
also has a very good contact kill.

Imocloprid is another chemical that has both properties. When using it to
kill fungus gnat larvae, we are using Imocloprid's contact kill properties.
I have used it on fungus gnats with very mixed results, from almost no kill
to very terminal. Last spring I noticed I was having much better results
with it on propagation flats containing ProMix than I was having with it on
Phals in moss. I think the problem is that chemicals are leached out of
moss very quickly (If not leached out, at least moved out of the surface
(were the larvae are) to deeper in the pot). I have played with this idea a
bit and found if I can avoid watering for at least two weeks after an
Imocloprid application I get a much better kill.

In this thread Ray talks about using insect growth regulators. I have tried
some and had very poor results with them. I now think the problem may have
been that they too were being leached out of the surface of the mix before
they had a chance to really work. One of these days I will dust off the bag
of Adept and try it again with the plants only receiving light misting for a
couple of weeks after application.

Pat
"K Barrett" wrote in message
...
I read about an new (to me) product called Bayer Rose and Flower Insect
Killer that has Imocloprid and something called Clyfluthrin (sorry if I
spelled that wrong). Label says its a systemic and kills on contact.
Those seem to be counter intuitive to me, how can it do both? I always
thought an insecticide was one or the other.... ... I am assuming the
Clyfuthrin is the systemic/contact killer of adults while the imicloprid
affects newly hatched young. Anyway, I've tried it and it sure knocked
down
a blooming fungus gnat problem, on the plants potted in sphagnum. I have
yet to see if it truly lasts 30 days.

K Barrett

"Pat Brennan" wrote in message
...
Most Mal labels that I have seen give a range for use. I have had no
problems at the lower rate, but have 'blacken leaf margins' on tender
phal
leaves at the higher rate. Mal 57% EC calls for 1 to 2 teaspoons per
gallon
and I would use it at between 1 and 1.25 teaspoon per gallon in late
afternoon or on cloudy days. Check your label and see if it does not
give
a
range to use, I think 2 teaspoons might be a bit strong. BTW, Mal is no
longer labeled for greenhouse use.
Pat


"K Barrett" wrote in message
news
I follow the directions for 'ornamentals'. I understand broughtonias &
their intergenerics can have black leaf spots or blacken leaf margins
from
malathione use. No scientific evidence for that, just an opinion from
an
old grower I know.

K Barrett

"jadel" wrote in message
oups.com...
How much 50% malathion per gal. of water is needed to treat for scale
and other nasties on orchids? The directions on the malathion
package
are not specific about orchids, referring only to "ornamentals." I
think 2 teaspoons per gallon is what I want, but I am not sure.

Are there any orchid genera which will be harmed by malathion?


J. Del Col