G13 strain problems - necrotic leaves

[millstb1]

hello all out there ...
I've got 4 strains growing under CFL's at this point: AK48, G13, Crystal and F*cking Incredible.
Three are doing well but the G13 has what looks like nute burn. Here's a shot:

Details:
Coir, perlite mix
18/6 lighting under about 180 watts 5500K CFL's
All germinated at the same time, no nutes til second week after seedlings popped
All water ph'd at 6.0, 180 ppm good well water, no chlorine
Only one good nute watering so far which is Earth Juice based:
5 ml/gal Grow, 5 ml/gal Microblast and 5 ml/gal Catalyst and 5 ml/gal Hygrozome

Here's a picture of one of the F*cking Incredibles which are doing fine under same program

I have 3 G13's and all have this problem. I used the two most mature and a week after the first nute watering I gave one plant (Rosie) the same nute schedule as the first week. The other (Sarah) I only watered. I did add 1 tbs/gal Epson Salts as Sulphur was listed in the Nute deficiency table (see 420 post).
After 4 days both plants essentially look the same; no improvement in either one.

I also thought Iron def. but EJ Catalyst covers that metal.

Grasping at straws ... any suggestions ??
Here's shots of the 2 other strains

That's crystal

That's a 4 shoot AK48 (early problem with Thrips and I used way too much Neem Oil which killed off a lot of the young growth.)

cheers all,
millstb

 

[Lester Freeman]

in order for efficient nitrogen uptake, the pH should be generally a bit more alkaline, you could be locking something out with a pH that low..

but check out the problem solver/pictorial in the Problems/Pests/Diseases in the Grow room.

Difference in genetics may also play a role.

Best of Luck.

 

[millstb1]

Hey Relaxed Lee ...
thx ... I checked the ph of the water coming out after accurately measuring the ph of the water going in. Going in it was 6.0, coming out it was 6.8, so I extrapolated and figured the natural ph of the coir/worm shit/perlite mix was about 7.2; So my reasoning was that ph'ing the watering solution to about 6.0 would keep me in the zone where most all the critical nutes are being absorbed rather than being locked out.

fishcake pointed me in the direction of possible Potassium deficiency. I checked that out and sure enough, a number of their symptoms looked like mine. I have Earth Juice Meta-K which is 0-0-5, I'll try a light feeding on one of the stricken G13 plants...

thanks Lee.
cheers milzzzzzzzzzzzzzz