HELP! Younger leaves curling upward; older leaves have rusty spots

[QueerHobbit]

I'm growing Orange Crush, Tora Bora, and Canna-Tsu, DWC in 5gal buckets, 1200W LED. They get Flora Trio nutrients and Hydroguard (weekly water changes). I had some nutrient burn on Tora Bora and Canna-Tsu a couple weeks ago, but it didn't advance after I reduced the nutrient concentration by about 20%. I'm 9wks into bloom cycle, getting close-ish to harvest!

Two leaf problems that I can't figure out from the tutorials:

1) Younger leaves on Orange Crush and Canna-Tsu are curling upward on the inner/lower margins (closest to the petioles); worse on lower growth tips. I have no idea what this could be; there have been no substantial recent changes in light, temp, humidity, or air circulation. This started less than a week ago and got bad pretty quick on Orange Crush. Curling leaves are healthy rich green, not thin or brittle.



2) Older leaves on Canna-Tsu have had some pale/rusty specks for a while (since mid-Sept), and they've just been gradually increasing. Under a hand lens, there definitely aren't any pests or mold on top or bottom of the leaves. Affected leaves feel slightly brittle. I am wondering if this is another symptom of nutrient burn, showing up more gradually? They also had four days of cooler temps (55-65°F) at the end of October, but didn't seem harmed immediately after. I'm not super worried about this, because it's so slow and minor, mostly just curious.



Thanks!

[Gluteous]

Can't tell anything from the photos. Can you post some under better light?

[QueerHobbit]

Added some new photos with flash, let me know if those are sufficient! If not I can set up a clip light.

[Rwise]

Whats the PH?

[QueerHobbit]

I vary it between 5.5 and 6.5 typically. This week it's been at about 5.5.

[Gluteous]

I don't know man. That leaf pic sure looks like pest damage but you'd see that under magnification. Sounds like you're close to chop so just ride it out I guess.

[QueerHobbit]

I checked with my bro and he said it's actually pretty normal for leaves to go curly close to harvest ~ I googled it and sure enough, a bunch of "ready to harvest" images have leaves curled up really similarly to mine. *shrug* Live and learn!

Still not sure about the speckling, you're right that it looks a helluva lot like pest damage. But like you said, I'm pretty close to harvest so I'm just gonna wait it out!

[UndergroundFarmer]

I had some mystery spotting on otherwise healthy plants. I looked broadly at where the spots were then noticed that all the spots were along the path of an oscillating fan that was pointed too low! I'm glad I didn't freak out and start adding crap to the water that they didn't need.

[BudzPow]

That Canna-Tsu looks an awful lot like my plants did when I had spider mites. I checked and rechecked, thought it was from my light being to low and after I was sure everything else was in order I was scanning over leaves one day. I thought this tiny spec was just a piece of my soil that got on the leaf and as my thumb got really close to it it moved just a tiny bit. I broke out my microscope that I connect to my phone ( https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 ) and sure as can be it was spider mites.


EDIT: It could also be Cal/Mag deficiency if the leaves are newer growth and in the light but the leaves that aren't as exposed to light are doing good.

[grouchyoldman]

I had an infestation of Thrips last grow and the leaves looked exactly like yours. The bugs are tiny and mobile so you might have a hard time seeing them.

Here's the GWE article:

https://www.growweedeasy.com/cannabis-plant-problems/thrips

I nuked them with permethrin but there are other treatments.

Good Luck,

-Grouchy

[Rwise]

Do look them over with a 30x zoom lens, curling leaves are often bugs.