Sick Mephisto's heading into flower. Please help!

[JBLUE]

Hello All,

Been a lurker here for years now but now I have a problem I cannot seem to solve without personalised advice!

Thanks in advance for any responses.


Problem: Yellowing of leaves at edges, blotches, curling + burnt tips and slow growth, purple stems.

Medium/grow method: 70/30 Coco+perlite in 3 Gal fabric pots, hand watered until rooted out then put in autopot trays.

Feed: and supplements used: GH Flora Trio + CaliMagic. Have been using the Lucas formula (just micro +bloom +calmag) which has been successful for me with all other auto’s I have run.

I start at 2/4/5 and current feed in res at 6.5 weeks old is 4/8/5 (per US gallon). I keep the calmag at full strength from the start to account for the use of coco and high power LED lighting. PH is 5.8 after mixing and rises over 36 hours to bang on 6 where it tends to stay.

water source: Tap (soft water) - EC unknown.

Strain/age: Mephisto CDLC day 45

light used: 480w Quantum board @ 36” height running 24/0. Homemade frame running 4 x HLG QB96 Elite V2’s running in parallel off a Meanwell 450w-54a.

Climate: 24c 60-70% humidity (dehumidifier en route) -VPD issues?

Additional info: Waited a long time to get my hands on some Mephisto and sadly I have not done them any justice.

I don’t know what is wrong, whether it is a deficiency like potassium or nute burn. I thought at first it may have been light burn/stress as my light is ridiculously powerful. I have raised it and dimmed it and yet the problem persists and progresses.

These ladies are really getting into flower now and I am sure can be saved but I am lost as to what to do.

 

[CannabisMingus]

to AFN @JBLUE - you will find a very helpful community here.

I'll take a stab and say it looks like a K def but could be a lock out of some sort. We really need to know the EC of your tap water. Excess Ca or Mg can lock out K. My guess is that your tap is high in Ca and/or Mg causing a lockout - but I will defer to the experts. Assuming normal temp ranges I don't think it's a VPD issue. Good luck!

 

[namvet25]

Do you no the Par value of your light at different heights? Try going leshours on with your light. Have you been feeding micro nute?

 

[Weedkiller]

Hello and welcome

 

[Weedkiller]

I agree it looks like its the nutrients. I use gh trio as well. Hopefully we can get you sorted out. Lots of good reading material here so my suggestion is read some journals and look around at other posts.

 

[CannabisMingus]

Also, just noticing on your younger plants that you appear to be watering just around the plant. I believe the consensus is that you need water the entire pot due to the extremely rapid root growth potential. HTH, IMHO, YMMV, etc.

 

[Weedkiller]

Around the outside of the pot like he said.

 

[JBLUE]

I agree it looks like its the nutrients. I use gh trio as well. Hopefully we can get you sorted out. Lots of good reading material here so my suggestion is read some journals and look around at other posts.

Obviously it is strain dependent but could you please tell me your feed schedule for an auto at 6 weeks old (or early bloom). Do you go by fractions of the feed schedule on the bottle?

 

[Weedkiller]

Herea a pdf

 

[Peacefulgarden]

I would try lower ph and see run off ph and ec