What do think it is?

white domina from kannabia seeds, almost 3rd week of 12.12
Ocean Forest at 6.1 ph and 850ppm

I’d like to know too. 2 of my nine clones have the same symptoms although they’re 6 weeks into flowering not 3 weeks. The only thing I know is what I did differently with these 2 plants. Because my previous flowering ran long, I didn’t have enough pots for all my clones. So I placed 2 of the smallest plants in the flower room -- I didn’t have the heart to toss them and I wanted to see what a foot tall flowering plant would look like. When two 3 gallon pots became available, I transplanted them using new promix and I didn’t add any espoma lime (calcium / magnesium). Also, both plants ended up getting over watered for some time but never enough to crash the turgor pressure. The one nice thing, except for their appearance, is they are covered with twice as many trichomes as their sisters and the trichomes are much smaller and extent to the tips of the leaves. It must have something to do with ph, calcium, or magnesium – I would think.

Heat stress????

do some of the nutes get on the leaves when you water?

I don’t think it’s heat stress and not burn; it’s winter and I wish I had a warmer flower room. Plus the spotting extends further down the plant.



But that was my first guess.

If it isn't spider mites then my best guess is a salt toxicity. Sodium I'd guess, impacting the uptake of calcium, magnesium, and potassium. More Calcium deficient though.

The pH is definitely too low, so that reinforces deficiency based on pH but I don't know if it is pH alone or pH and sodium. If you've been using Distilled or Dionized water that could be a contributing factor.

Bring the pH up to 6.5-6.6 using saturation with a bit of run off on a 7.0 solution. Once the pH is balanced then you can address the elemental issues. Keep an eye out for mites too.

I think I have the same problem ( I grow in water made from melted snow, with original pH of 7 ). My nutes ( Grow/Micro/Bloom) are at 690 us/cm (441 ppm) and the pH is around 6- 6.5( by mistake a drop it to 4 but recovered quickly with a pH UP solution. 2 days ago by digital pH tester died and until the new one came up I will use an aquarium pH tester kit with droplets ). Today I just added some Hygrozyme to my reservoir to help the roots. The plants are growing very nicely but the brown spots and the leaves twisting make a little concern.