I've seen some cases of a grow light damaging a growth point but that growth point was nearly touching the light- like millimeters to a centimeter away. The damage on your plant (the brown crusty looking stuff) looks too spread out to be caused by proximity to a light. The really red color at the top might be caused by a close light. I haven't had experience with using Bonide but if that were my plant I'd suspect that the younger more tender parts of the plant didn't handle the application of Bonide well. Exactly what Bonide product did you use? I tried Googling it and found Bonide is a brand name for a few different products.

I used this one.

You are right. The plant was about 6 inches away from the light. as the you leaves grew the scarring becomes more pronounced. The plants under purple lights was more affected, although the ones under the whole LEDs did also have them albeit to a lesser degree. I noticed on only particular cultivars do this. I actually tossed it out now. I’m just curious if anyone else has this experience overwintering certain succulents.

You would not think a granular treatment would cause that kind of reaction, but who know what kind of effect a systemic might have on a succulent. In general pesticides are rarely tested on succulent plants, so there could be unforeseen reaction.

Your lights are not on very long, so they didn't get burned by over exposure. 6" could be too close, but that depends on the strength of your grow light. What does the manufacture recommend?

The photos below are plants I damaged under a grow light. It was not as close as you are to get that damage, but my lights are also 1000 W. .

I haven't used Imidacloprid in granular form but I have used it in liquid form and had no issues. Might it be a bad case of oedema? I don't see it very often on my plants (I'm more of an underwaterer than an overwaterer) so I'm not so great at ID'ing it.

I do not think lights that are 6" away, and are LED, would cause this UNLESS:

-Plant was under lights while being treated (I never used Bonide and do not know how long there is a danger of phototoxicity)

-Plant has bug or oedema damage

Some plants are more 'sensitive' to both light and chemicals, especially lighter-colored ones.

Why did you use Bonide?

I've used Bonide systemic granules on a lot of different succulents and cacti before and didn't have a problem, but, on the other hand, I didn't use them on Echevarias.

I heard of plants burning under 6500 K LED lighting. I use 5000 K because that's all walmart sells and it;s cheap and about 18 watts a shop light. Mine have responded well to it. I have upgraded to a few 50 watt 5000 K lighting and they are doing better. My plants are about 8 - 12 inches away from the lights. The tops of some plants are about 1 inch away with no difference.

I've had similar issues, and in my case it was from them being too close to the light. I had a lot of this last summer before I moved the grow light a little further away, and just pulled two plants yesterday that had similar looking damage. I looked at them with a magnifier and couldn't see any pests, so I'm thinking they are just more sensitive to the light than most of my other succulents.

Kerri

What plants do you have? How close to the lights they were, and what kind of lights are yo using?

I have a variety of succulents. The ones most affected mostly Echeveria, the most recent was a Premadonna. The light is a 4-tube T5 6500k. When most were affected like this the light was about eight inches above. It's now 12 inches above and most are happy but it looks like it was still too much for the Premadonna.

I am surprise that light as far as 8" would burn any succulent. I am quite sure you would acclimatize plants to lights. I have many about 4" away, some as close as 2" and literally none further than about 6" - maybe occasional very small pot sneaks in when moving plants around, but I try to keep them closer. Otherwise, I do not see much of point of having lights. Further they are, more loss of intensity, and too far is just too far. I use few different sources, including ones you mentioned. I burned few plants when I didn't acclimatize them. Few I burned were kept under CFL lightbulbs. Those bulbs emit some heat. LED is much cooler. I agree that some are just too sensitive, but even those I can't see further than 10" away? JMO and experience (I keep more than 200 succulents under lights during winter), and I would think others may disagree...

Some ppl keep plants 8 - 12" away. Stush said in previous post: I heard of plants burning under 6500 K LED lighting. I use 5000 K because that's all walmart sells and it;s cheap and about 18 watts a shop light. Mine have responded well to it. I have upgraded to a few 50 watt 5000 K lighting and they are doing better. My plants are about 8 - 12 inches away from the lights. The tops of some plants are about 1 inch away with no difference. (I realize he is talking 5000k, not 6500k).

I am not familiar with Premadonna (Prima Donna or Pre madonna...), had to look it up. Maybe it is quite sensitive to light levels. Very hot sun could damage many succulents, so could light that is too close. Premadonna (or whatever correct name is), looks like beautifully variegated plant from Korea. Couldn't find much info (parentage etc). Someone remarked that colors could vary; is yours mostly red-salmon?

I think they were more prone to burn because its a 4 light setup, which can make it quite intense. I had a cheaper setup before with two lights and it wasnt enough for mine. The ones that want more light I usually just sit on a riser of some sort so they can be closer. What's left of my Premadonna (many spellings as you saw) is mostly black and salmon.

Here’s an update of the plant: I ended up with a mini topiary after pulling all affected leaves and chopped the top off.

Thanks Rina. This is now outside in full sun in a south facing yard.

Chris, another plant pulled from the edge of the abyss - great job.