insecticide/fungicide in S/H?

[the jive turkey]

I have persistent mealies that need killing....
how should one apply insecticide/fungicide to the plants in S/H? Dunk or spray? Rinse while wet, or let dry or rinse not necessary? Should one worry about the chemicals left in the water in the bottom of container?

 

[bwester]

if smell is not an issue, I always trust good ole malathion. I'd just drench the whole thing.