I am new to this forum, but not new to paphs and phrags. I have had a persistent and resistent mealy bug problem for a long time. I whack them back with one thing and another. I grow mostly under lights in a grow room with some windows for some sun. I want to try a systemic root drench using Bayer Advanced Fruit, Citrus and Vegetable concentrate. The active ingredient is Imidacloprid 0.235%. There seems to be disagreement on various forums and postings on the internet about the concentration to use on orchids. The Bayer product does not list orchids. I understand that this is because they didn't test this particular mix for orchids because they didn't expect to sell much into this specialized market. Many people seem to use Imidacloprid for orchids, however. It will only work if it gets into the roots as it is only transported up from the roots into the plant and not down from the leaves.

The concentration on the label for vegetables works out to 3 tsp per quart or 12 tsp per gallon. This comes out to about 35 ppm. I have seen people recommend double that concentration, but going higher is always risky. When used with vegetables, the product will stay in the soil for some time. With orchids, it pours through the media and out the bottom, hopefully wetting the roots on the way. I would like to know what concentration people are using and if they have found that they need to treat a second time or more to really kill the tenacious mealy bugs. I have plants that are in bud, in bloom and not yet in bud or bloom. I treated about 20 plants yesterday as an experiment. I appreciate your comments.

Ken

Honestly, I've never considered the concentration of imidacloprid in a product for treating my plants. I just use the Bayer Rose and Flower spray on my plants. This has .0120% imidacloprid in it, if that's any help.

You must be using the dilute spray formulation. I just did the division and it looks like the spray you are using is 1/20th the concentration of the concentrate I am diluting to about 1/64th. So the spary looks like 120 ppm if my math is correct. As a spray you are putting much less on that the root drench I am using, which is probably appropriate.

Perhaps someone else is using a root drench and has been diluting the concentrate.

Thanks for reminding me that they sell a spary that is pre-diluted.

Ken

Well agreed with what Nick has posted.

Welcome to the forum by the way!

hi Ken welcome to the site!

The age old system of spraying the infected plants with soapy water works just fine for me.