Try 0.5ml a liter every 2 weeks. They say to use 1 ml+ when fertigating but for threating infested water and swamps they use about 0.2 to 0.4 ml a sq meter, even when sprayed from airplane. And each mg of the stuff supposed to have 1300 kill strenght. I suspect it will work even at lower dosages, and you might try for that once you start controlling them, slow and steady drop the dose till you see them, and when you do see any of them, go back to the dose used 2 weeks before.
Be aware that they say flooding is the way to use it, and that other fertigation techniques might result in uneven distribution of the stuff in the media. Which I personally think is bs since they will go where the moisture is, and also roots tend to be where water is given, as well. I think they just want to say better spray it or flood it so you know whole area is treated, than have a few bad emitters or sprinklers leave some area untreated. In your case, you'd have dead plants if water would not reach them, so it shouldn't get to be a problem.
Be aware that they say flooding is the way to use it, and that other fertigation techniques might result in uneven distribution of the stuff in the media. Which I personally think is bs since they will go where the moisture is, and also roots tend to be where water is given, as well. I think they just want to say better spray it or flood it so you know whole area is treated, than have a few bad emitters or sprinklers leave some area untreated. In your case, you'd have dead plants if water would not reach them, so it shouldn't get to be a problem.
