Leaves no longer lush green - 3rd week flower

[MoistOreos]

Problem: I'm having a yellowing and brown/bronze/copper like spots of my leaves . problems start occurring once i flip into flower. last harvest suffered because i wasn't able to fix the issue. resulting in small buds, weak plant, stem and stalks were very flimsy, dry curling yellowish leaves on entire plant, making it very hard to trim.


SOILLESS GROW - HP Promix

Strain - Indica - grand DADDY
# of Plants - 4
Grow Type - Soilless HP proMIx mixed with miracle gro
Grow Stage - 3rd week flower
Bucket Size - 5 Gallon
Lights - (1)750 Watt gavita
Nutrients - General Hydronponics
Medium - 75% Perlite 25% Vermiculite
PPM - 900
PH - 5.5 -6.5
RH - 60% to 70%
Room Temperature -25- 29 degrees c
Solution Temperature - 18- 23 c
Room Square Footage - 10' x 10'
Pests - large spider mite problem

Problem: My leaves are no longer remaining lush dark green. Any dieas?

 

[MoistOreos]

leaning towards a calcium or phosphorous deficiency, thoughts?

 

[MadScience]

pH seems low, but that's just a guess. Usually broad die off like this points to fert burn. Can you post pics of the whole plant?

 

[MoistOreos]

this girl is 5 days to harvest

 

[Suntana]

Looks like mine do at 6 weeks, my medium ph dipped a lot, due to salts building up.

 

[MoistOreos]

she is def suffering from something. my buddys 4 girls are still lush green, no yellow curling leaves and the buds are twice the size. we both grew ours at the same time

 

[MrCanada]

Check bottom of leaves, and rest of plant for any small webbs. It kind of looks like severe pest damage. Possibly mites

 

[MoistOreos]

I def have an infestation of spider mites but was also wondering if it could be some sort of nute deficiency aswell.

do spider mites cause the bronze rust like spots on the leaves if leave untreated?

 

[TheDarkTriad]

yes i think they do