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