Burn or Def

[FKNTWSTD]

I am running a air cooled 600W HPS with constant temp and humidity levels. I just entered the 4th week of flowering (3rd gen). These plants are normally very strong but have weak stems and have been yellowing and getting crispy. I don't want to rule out nute burn but nothing has changed with my PH or Nutes with the exception of adding a flowing booster... What do you think this is?

 

[Irollfatties]

Looks like nute burn. You may not experience nute burn until after weeks and weeks of build up in the soil. Whats the ph of the run off?

 

[grobofotwanky]

I'm gonna say def. Plants soak up more nutes in full veg and full flower. At 3 weeks your plants are through the transitional phase and preparing to form buds. Look at a phosphorus def HERE and you can make a better decision for yourself. Hope you get it sorted out and good luck.

 

[grobofotwanky]

Weak stems can slso come from a K def I believe.

 

[Sure Shot]

Back off the nutes for a while.
She's a little burnt.
Focusing on creating an optimal environment for the plant to synthesize energy.
Happy growing.

 

[FKNTWSTD]

Looks like nute burn. You may not experience nute burn until after weeks and weeks of build up in the soil. Whats the ph of the run off?

6.25 about the same as it goes in... I am leaning towards burn because the dying leaves are shrivled and crispy... maybe salt build up too... flushing them now either way.

 

[FKNTWSTD]

Sounds like the best plan of action, I am flushing them right now to make sure there isn't a salt build up. I will reintroduce nutes slowly... I am just confused as to why I didn't have a problem with nutes until the last few days. Can KoolBloom with Phosphate and Potash really have such adverse effects?

 

[Sure Shot]

Any fluctuation or increase in any parameters will have an adverse effect.
Nutrient solutions don't even make my list of primary parameters.
If you read my signature, you'll see what I mean.

Plant energy is derived from photosynthesis, right?
Well, this requires a ratio of photons to H2O to CO2.
If your plants vascular system is impeded by nutes,
then the heat radiation from the photons will not be dispersed through photosynthesis.
This will result in a literal burn of leaf tissue.