Sugar 🍃s are turning yellow and hard brown near the ends help plz

To be honest, your grow doesn’t look ideal. I suspect the tops of your plants are too close to the light, likely causing heat stress and light burn at the top. Overall, it seems like you ran into several issues during the grow: – The pH of your watering solution seems off. – Temperatures appear too high. – Humidity is likely too low. – Lighting intensity may have been excessive. These factors clearly affected the plants, and unfortunately, that will probably show in the final product. I recommend reviewing these points and aiming for more control in your next grow. After all, we all want to help each other out – so everyone can enjoy better weed.

All the damage is at the top... possibly too much light. A lot of leavs close together at the top, too, which means at one point it was stacking nodes quite tightly. If way over 35-40 dli, dial it back.. even if near top end of that recommendation maybe dial back 10-15%. (10-15% less dli, not 10-15% on your dimmer knob, necessarily.) If this is soilless/hydro, a rundown on ppms per nutrient molecule would help a lot. If you did the bro-science and blasted it with P and K, could be lockout form that, too. That has chlorosis at the top that will progress to dead spots if you ignore it long enough. If significantly over 180-200ppm K, at some point it will be a problem even if it takes weeks to see something. Feeding over this will just increase K in runoff. If P is way over 80-100 it'll start causing issues. Really only need 50-60ppm of P. the rest is just pissed down the drain in runoff. this also depends on some orthodox levels of the other nutrients.... See "Mulder's Chart" for complexities of interrelated nutrients. if in soil, these numbers are useless to you.

Without a diary and/or A LOT more information about what you may be doing or may not be doing, this question is impossible to answer accurately based on a few pictures alone. You have many issues though, that is for sure. Could be any number of causes.........but it is not a magnesium deficiency that caused this!

The plant cannot process magnesium when PH is low. Therefore, the plant has a magnesium deficiency.

Low PH. Callibrate phmeter with buffer solution