Hi. Some kind of deficiency or sickness appeared o...

Don't start throwing things at her until you verify PH and TDS in soil. Of the main nutrients the closest this resembles is Phosforus deficiency. There's a great site for helping diagnose. Put " 11 common cannabis nutrient deficiencies" in browser search and you"ll find it.

What are the growing conditions. To avoid issues we need to have the basics met for her to thrive. This could be from a few things, one being to hot and humid with poor air circulation but you appear to be only having one of the plants in there doing this. Different strains can require different conditions though. Bad PH can also cause this from a deficiency, 6.4 PH is on the high side for marijuana but I have had success in that range but prefer it lower. If your sure that's fine then don't flush, remove the affected leaves and double check all the conditions, Light and height, Humidity, Temp and Air irculation, Watering, Feeding, Soil. At this stage my temp is 78 degrees and 50ish humidity Since I only grow one or two plants at a time and this was my plant, I would transplant her with as least amount as possible of current soil still around her roots and put her into fresh Fox Farm Happy Frog and you won't have to feed her for 3-4 weeks. That's if she is not an auto.

Das liegt definitiv an der falschen Calzium und Magnesium ratio. Da fehlt Magnesium auf alle Fälle. Erste Hilfe ist Bittersalz auch Epsomsalz genannt. 2 Teelöffel davon in 0,5L Wasser lösen, pH-Wert auf 6 einstellen und dann morgens und abends 1x auf die Blätter sprühen.

Stop using ca mg

Phosphorus or magnesium deficiency, think magnesium more likely, girl is not in flower yet.. Epsom salt works better, i would not use CalMag , when i miss only one part .. ( if you plan just to increase calmag, you are way off from proportions anyway, but i never liked how biobizz calmag behaves , so rethink before pouring a lot of it ...) Ussually its related to watering habbits in soil. Overwatering causes it very often , aka toots have no wet/dry cycle. No diary, hard to tell 4sure, but if firstly leaves went into tigery stripes and later necrosis appeared - 100% magnesium. If necrosis came up together with bleaching of leaf - phosphorus, lack of it.