nutrient deficiency in chronic plant...help?

[s00thsayer]

Growing chronic from serious seeds and having a deficiency problem. Using tap water, dyna-gro grow fertilizer, and sunshine 4 peat/perlite mix. Pics attached. Any ideas? Right now the plant is showing signs of pH stress and overwatering (from flushing to drop the pH).

Background: The deficiency started after about 3 weeks of veg growth--the leaves were green, just slightly pale green, so I increased the fertilizer dosages. The leaves got darker but the blotching was still showing up in new growth. Thought it may be high pH and/or magnesium deficiency...pH was slightly above 7. I usually don't tinker with the pH and all my other plants looked health at the same pH so I added epsom salts to the feedings with no improvements. Added molasses thinking it might be another trace mineral missing (zinc ?)...no change in the plant health. I cloned the best looking branch to see if I could do better the second time around and ran into the same problems after the clone rooted and started growing. Decided to drop the pH this time so over the period of a couple weeks I slowly dropped the soil pH to 6.5...seemed to get worse and stress the plant. I've grown many strains with no problems...every other plant I'm growing right next to this girl looks great. I've seen hints of this deficiency in a couple other strains I've grown (big bang, ortega, and gforce) but a slight increase in fertilizer dosages seemed to fix it in those strains.

 

[RubeGoldberg]

If you continue to feed/water around 6.3 it should clear up for you.

When you mentioned the PH of the soil, does that mean you're using a soil probe to measure your ph?

 

[RubeGoldberg]

.

 

[s00thsayer]

thanks for the response. using a probe to measure soil pH....which is currently reading at 6.5. i flushed the soil until the runoff water (checked with the pH indicator drops test kit) was also reading 6.5 (slightly less). the dolomite in the mix has definitely been raising the pH to around 7 which it appears chronic does not like (assuming high pH is the problem). i'll keep lowering the water pH to keep soil pH at 6.5 for a few weeks and see if it clears up...if not i guess i'll give up on the chronic. finicky strains are not my thing. :|

 

[RubeGoldberg]

I personally don't trust soil meters whatsoever, litmus on runoff also gets tricky because the runoff will have color to it.

as you know, because certain nutrients are most efficiently uptaken at specific ranges, PH control even on plant that don't look like they need it is key to maximum yields.

at this point a digital PH pen like a Hanna or something will probably be a great investment and honestly, the difference in yield just by dailing in the PH will pay the meter off 10 fold quickly.

 

[s00thsayer]

the two way soil moisture/pH probe I have isn't dead accurate but it is close enough imo. the reading is off by a third of a point or so...and you definitely can't use it to measure water pH (measurement will be way off). i bought a 3 way pH meter before this one and it wasn't even close to being accurate. anyway...I'm thinking I should probably get a different potting mix for the acid loving indicas.

 

[moresntoil]

done chronic MANY times had SAME problem until I stopped using my tap water which is about 270ppm.

cant see your pics but sounds just like the spots I use to get, little dark brown spots.

chronic will use alot of nutients!

your spots wont go away, but should stop after you switch to "cleaner" water.

now we use spring water at 90ppm and everything is perfect, I went crazy for almost 2yrs trying to figure it out, thought my water was good enough, i was WRONG!

just my take on your situation

 

[s00thsayer]

Thanks moresntoil. I have wondered if my hard tap water could be part of the problem...though all strains i've grown with the exception of a few indicas have been fine with it. Hmm...i only grow a handful of plants for personal medical use and i'm not sure how much special attention I want to give to this strain. So....a better water source and/or more acidic potting mix? Damn the chronic. The mum is in flower and sucking down nutes like crazy (like you said) but is still a little fussy too.

 

[s00thsayer]

Tap water is 165 ppm...i think that is fine and I just need to find a way to keep the pH down.

 

[moresntoil]

hhmmm? 165 doesnt sound high to me, but to be honest im no expert so....
I did get a water quality report online at my water companies web site,

sodium@32ppm and
chloride@96ppm
and copper in the above 90% range on normal. and many other elements

so at different ph levels maybe you are taking in to much of one or two of your high end contaminats.

I would do what rube said and keep ph at 6.3ish, try different water and check everything else.....
Just my opinion, keep us posted

 

[Forest20]

What size container are the ladies in?

 

[s00thsayer]

3 quart container....looking grim now after the last pH flush...leaves got crispy....we'll see if she recovers. it's not rootbound (assuming that's why container size was asked?). all the other strains i'm growing at the moment look perfect. i've grown 18+ different strains to date and chronic has surprisingly been the most difficult to keep happy.

 

[bobman]

put them in a bigger container.

 

[s00thsayer]

recent water quality averages from the water company...

sodium 18
chloride 10
calcium 120
alkalinity 85
tds 230

 

[s00thsayer]

i transplant to 3 gallon containers when rootbound or when plants are approximately 14 inches tall...this plant is only 8 inches tall and is drying out the medium slower than most plants its size

 

[bobman]

have u taken it out and looked at the roots.

 

[bobman]

not just because of root bound either. i would take a look in there. are they getting a good wet dry cycle.

 

[bobman]

overall they do not look bad. i am sure they will grow through whatever it is. my bet is they want more space or they don't like being wet all the time. i dont think its anything major or to be to concerned with.

 

[s00thsayer]

i checked the roots after flushing...healthy white and were just over halfway down the container. no roots popping out the drain holes. the peat was saturated from the flush so i knocked off the bottom few inches of peat without roots and filled with dry peat to give the roots some air so it would recover faster.

 

[bobman]

yea, u know when they are young its hard to tell. my bet is they want to be more dry before feeding. overall with the other stuff your just chasing your tail. when you say the roots are only halfway down the container that sounds stunted to me. I really think give them a really good dry cycle. to bad you just gave them a flush because that is probably not what they want. i think your probably lucky it is not worse. is your mix pretty heavy? or is there a good amount of perlite in there?