Inside grow? Looks like burns from moisture on the leaves with the lights on, at the close distance the drops of water magnifies/concentrates the light in a small spot.
Thanks Rwise, that's a likely reason for the damage. It does look more like a burn up close. I'm a little skeptical tho because my lighting is entirely CFL (10 bulbs @ 40 watts each), and I moved them up and out of the way before spraying. I also inspected the plant two hours after spraying and didn't see any visible droplets. I wonder if the 91% isopropyl alcohol was too harsh on tender buds? All the white pistils turned red & shriveled up after the spraying.
Interestingly, I harvested and trimmed one of the most severely damaged buds and it looks surprisingly good. The trichomes are cloudy and in some cases turning brown, almost as though the spraying accelerated bud development. I reckoned it was a week or so out from harvest before spraying.
In any event, I would recommend extreme caution to anyone considering the 50/50 alcohol/water spray technique for spider mite control. My poor White Widow went from a beautiful gal to a tattered wreck overnight! I would probably have been better off to stop after the original Permethrin application.
Just to wrap this topic up, below is the background info from my original post.
Regards,
-Grouchy
==========Background========
I'm about two weeks away from a nice White Widow harvest and the dreaded Spider Mites are attacking! The infestation is still minor but they can ramp up fast. Looking for advice on safe treatment options.
I'd estimate a dozen or so fan leaves showed yellow Spidey spots a week ago, and I verified mites and their eggs using a magnifier.
Grow room temp and humidity are under control and fans are moving the air around a bit. There's a single WW female ending week 7 flowering, 12/12. The plant is growing in rich compost, and otherwise very healthy, lots of foliage, thickening buds. Water-only flushing in progress.
I have already applied two fairly heavy treatments of Permethrin using a fogger. Using the magnifier afterwards I can see dead spideys and black dead-looking eggs. *gross out*
So, should I just ignore this for the next two weeks then nuke the grow room after harvest? Or continue treating with Perm? Or treat with another agent like Spinosad.
I'm concerned about dumping anything on my budding buds, but Perm supposedly goes inert after a fews days. Same with Spino.
Lookin for some experienced advice here.
