I've had problems with thrips in the past. Despite how cold and dry (71-76F day, 60-63F at night, <25% RH) my grow tent is, these little bastards keep coming back. I found them on one of these girls in their third week of veg. I quarantined the infected one, applied a liberal treatment of neem oil mixture (with dishsoap) on two separate nights, and the thrips definitely stopped appearing. I checked on them closely. Daily. I went another week without seeing any signs of bugs (or new bites appearing), so I moved the healthy plants back into the tent. I saw how big they'd gotten in the mean time, and immediately flipped to flower. Today makes Day 15 since the switch to 12/12. The girls have really filled up their available space (Image 1). But to my horror, ten minutes ago I just found signs of new thrip bites and droppings on the topmost leaves (and a few inner leaves below the canopy). They still seem to be (fingers crossed) only infecting one out of four plants. But I know now that, since flowering has officially started, neem oil might no longer be advisable. Apparently it ruins buds? I seem to remember reading that, anyway. But I'm thinking about one last good dousing of neem oil/water/dish soap mixture tonight, before the lights go off, to try and wipe them out (or at control the population) as I head further into flower. Based on the pics provided, would you say it's too late to for that? As I said, it's day 15 since the switch. A lot of the initial stigma (pistils?) are showing, but not much bud production had begun yet. I only ask because at this point, I have quite literally no other recourse I can think of. I can't get ladybugs. No garden center for a hundred miles around has live pest control bugs to sell at this time of year. Most don't carry them to begin with. Amazon Canada doesn't sell live specimens, and Amazon US won't ship them across the border. What do you think?
You can get Stratiolaelaps on Amazon in Canada. These feed on the soil stage of thrips. If you’re Ontario or East of Ontario, try Natural Insect Control for other predators that will take out the adults. If you’re West of Ontario try Westgrow Biologicals in BC. They should both be able to ship right to your door. Next time you grow, and want to give beneficials a try, get Stratiolaelaps in in the start, and get Fallacis and Cucumeris in when the first true leaves have developed. And always have sticky traps to catch the adults. If you grow under 60% RH, you’re probe to thrips and spider mite, so if there’s a way you can humidify to get it up, go for it. Just don’t get the humidity too high. I see this all the time. People use neem, get some results, but as soon as its in Flower the pests are back and with a vengence. Beneficials are the way to go, from start to finish, IMO.
That's some interesting stuff to think on. Thank you. You actually nailed my location; I'm in Southern Ontario If anything, I thought that perhaps a dry environment was discouraging to pests. I figured that, if I ignored the humidity problem (and let it stay around 10-20%), the plants would slow a bit and stress in a small way, but the thrips might "dry out" and die, especially with the neem oil treatment. I was under the impression the dry air was helping the pest problem. But I guess that isn't the case? Damn.
In general, pests are tougher than the plant. Stressed plants release a pheromone that pests can detect, and the more stressed the plant is, the more it lures in pests. Spider mite is a big threat when RH is below 50%. The drier the climate, the better for them, and the worse for natural predators. Additionally, the application of neem or other chemicals seem to add to plant stress, so if it doesn’t work at entirely taking out the pests , it can make things worse. With “resistance” to pesticides, this is becoming a bigger and bigger problem every year, for all crops.