Holes, deformed growth, and no pests found. What is causing this?

Setup:
I am growing 4 OG #18 plants in 80/20 coco coir/perlite, and I am in week 5 of veg. I am using a 500 Watt (true wattage) LED 32" above the top canopy. I am using GH Flora trio as my nutrients, and I did not use any Cal-Mag supplements for the first four weeks since I tried to buffer the coir myself. In the 5th week I have added about 2.5mL per gallon of GH CaliMagic (roughly 150ppm) every other feeding, and I use ~400ppm nutrients in the ratios 5mL:4mL:1mL (Gro:Micro:Bloom). I typically water once every 24 hrs to get 20% runoff.

Problem: In the first week of vegetative growth, I saw a few holes in leaves but no signs of pests. I didn't apply any pesticides and the problem went away. After a few weeks of healthy growth, the same symptoms appear to be coming back. There are twisted new leaves, holes and damage in some leaves (which mostly appears on new growth), and the new growth also seems light green or yellow. I have also seen signs of calcium deficiency (yellowing between veins and rust colored spots on some leaf edges). I have also taken numerous leaf samples and have not seen any signs of bugs on either sides of leaves under 80x magnification. I think the problems may be due to physical scraping of the plant on the SCROG, stress from pruning or topping, or a calcium deficiency, but I am not sure which (if any) is the true cause. Any help diagnosing my issue is appreciated.


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You have heat issues among other problems.

hotrodharley said:

You have heat issues among other problems.

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The temperatures range between 65-82F, so are the temps too high or too low? Can you elaborate on the other problems you commented about?

beepy1 said:

The temperatures range between 65-82F, so are the temps too high or too low? Can you elaborate on the other problems you commented about?

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The shape the leaves have taken. Slight canoeing but with the serrated edges up to dissipate heat. The twisting of newer growth. The canoeing might also be helped along with a calcium deficiency.

hotrodharley said:

The shape the leaves have taken. Slight canoeing but with the serrated edges up to dissipate heat. The twisting of newer growth. The canoeing might also be helped along with a calcium deficiency.

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Would heat issues cause the holes in the leaves too? I thought the plants should be happy at 80 F, but maybe they are not. Is this a common problem with 80 F temperatures (granted, the temperature at the leaf surface may get up to 85 F maximum)? I did have a few days where the relative humidity dropped to 15% for some time, I wonder if that could cause some of the issues I'm seeing.

beepy1 said:

Would heat issues cause the holes in the leaves too? I thought the plants should be happy at 80 F, but maybe they are not. Is this a common problem with 80 F temperatures (granted, the temperature at the leaf surface may get up to 85 F maximum)? I did have a few days where the relative humidity dropped to 15% for some time, I wonder if that could cause some of the issues I'm seeing.

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No idea on the holes. See any caterpillars or moths? Even little moths? Low humidity increases heat issues at the tops closest to the light first. Leaf droop as well.

I'm going through all this like every winter for me. Low humidity, woodstove for heat lowering it even more and below 0F outside so open windows are not a real option. I've got every plant showing heat issues even with an air cooled reflector. My humidifier just took a dump, it's 50 miles to Fairbanks and etc. Just do your best.

My humi took a crap and just for a shot I took a soaking towel hung it in front of a fan and it worked very well for about 12 hours.

Thank you both for your advice. I'm still stumped on the holes in the leaves though. I have looked over the plants many times and have not seen any sign of caterpillars or moths (or any other insect). I had caterpillars on my outdoor plants last year, but I've been pretty careful not to bring any bug into the grow tent. The strange thing to me is that the highest leaves aren't always the ones with the worst yellowing/damage. It seems like the newest growth (even the growth about 6 inches below the top of the SCROG net) is being affected the most.

What about pH? Might be more than one thing going on

Beachwalker said:

What about pH? Might be more than one thing going on

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I pH the nutrients to 5.8-6.0, and the runoff typically is around 6.2 the next day. I did a slurry test (with topsoil, since I didn't want to damage roots) and it measured pH 5.8. My meter has been calibrated too.

id look at the possibility of broad mite or russet mites

almost impossible to see and don't make webs

maybe.....!

You didn't FIM did you?

im4satori said:

id look at the possibility of broad mite or russet mites

almost impossible to see and don't make webs

maybe.....!

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Would they be visible under 80x magnification? I've looked over many damages and healthy leaves on both sides and I haven't seen any mites or mite feces. The other strange thing is for the last 5 weeks the problems seem to stop for a while, and then problems appear again a week or more later. If I had a mite problem, wouldn't they spread quickly in a few weeks? I haven't used any pesticides so far.

shawnery said:

You didn't FIM did you?

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I didnt FIM, I topped them about 2 weeks ago. I may have physically damaged the newest growth when I was working them through the SCROG though. Would FIM-ing cause the issues I'm seeing?

Exactly!

I think those ones near the top are just side damage from topping or working with the plant. I have a bunch that look like that after I FIM. I think the physical damage just looks like breakage from you.

Good to know! Does the coloring of the new growth look normal to you? If you think you see any deficiencies please let me know.