What to use next in rotation?

[kmccormic]

Hi Folks:

I believe what I have is Thrips. They are teeny tiny, smaller than a mechanical pencil tip. I couldn't get a good look at them even using an Optivisor and flashlight because they are FAST! Dark brown or black, living only in the medium, and possibly winged. How do people get these things to pause long enough to positively ID them anyway? Never could find them on the plants themselves, only ever in the medium if I watered. Never any webs. No red residue on a paper towel if I swiped the undersides of the leaves. I think they came in on 2 plants I'd bought even though I quarantined them for 2 months and they were clearly just repotted when I got them. I couldn't figure out why my plants (new and old) were suddenly dropping leaves or why promising buds just stopped. The new plants went to a mushy bud 2 months in or dropped the spike. I initially thought it might have been due to new home bud blast until I spotted critters in the medium.

So I whipped out my reference by Sue Bottom on what works with which bugs to try to ensure I always used a different mode of action with treatment. I used an Imidocloprid spray on the plants and medium, which seemed to cut them down immensely, then 2 weeks later a malathion spray and drench. Some of the plants didn't seem to like the Malathion, (the Slc really didn't like it, several new shoots turned black overnight even though it was away from any strong light, that was traumatic for me.) It's two weeks later, I haven't seen another pest anywhere, but with egg laying cycles what they are, I don't trust that the next generation isn't just about to hatch, and it only takes 1 fertile female to start the whole cycle over again. I'm trying to decide between Orthene and Bifenthrin as a next step. The plants will be staying indoors for another 2-4 weeks anyway, so phototoxicity shouldn't be an issue.

Orthene is systemic spray and drench, aspects which I like. I have never used either before and I'm nervous about the dosage to use per gallon (I use a quart bottle) which will be safe for orchids in general, and I have a concern about using two systemics so recently. And could you use them together with fertilizer or stick to just plain water? If I use Bifenthrin, what dosage for that?

If I've mis-diagnosed the pest, doesn't Orthene cause an explosion of mites? I'd hate to undo progress if I've determined the wrong pest.

Thoughts? Advice on dosage? All ideas welcome.