Bottom/middle Leaves Are Turning White

[MrBlackThumb]

2 weeks ago, I flushed my plants because of a nitrogen toxicity.
Then, I fed them 3,5g of maxibloom (half strenght), noticed it wasnt enough and gave them a full dose a few days later.

Now, my bottom and middle leaves are turning yellow, almost white from the start of the leaf all the way to the tips.
I have never seen this problem before and pictures of deficiencies/toxicities doesn't help.
What's going on here ?

1. Are you growing from seed or clones? Seed
2. How old are your plants? 2 months from start
3. How tall are your plants? 1,4m
4. What size containers are they planted in? 3 gal
5. What is your soil mix?
6. How often do you water and what type of water do you use? every 3-4 days, tap water
7. What is the pH of your water? 6.3
8. What kind of fertilizer do you use and what is its NPK ratio? Maxibloom, 5-15-14
9. Do you foliar feed or spray your plants with anything? Epsom salt
10. What kind of lights do you use and how many watts combined? HPS, 400w
11. How close are your lights to the plants? 50 cm
12. What size is your grow space in square feet? 3x3
13. What is the temperature and humidity in your grow space? 74-68F, 35% humidity
14. What is the pH of the soil? 6.3
15. Have you noticed any insect activity in your grow space? Fungus Gnats :@
16. How much experience do you have growing? 2 harvests

 

[MGRox]

I don't at all consider my self an expert at visual diagnosis and I normally read rather than try to reply. However I'll give this a go.

This appears to be on a lower older leaf, is this correct? I know it may sound like your swinging back and forth here; but (to me) it appears that some nitrogen is being mobilized out of that leaf. As well there is some P- on the petioles, but that wouldn't cause the color change you see on the leaf.

My guess would be that you can probably hit it with fertilizer again, or if you've continued the 1/2 strength possibly raise it again. 3.5g of MaxiBloom comes out to a 46 - 60 - 107 profile (npk, ppms) which wouldn't take long to need more nitrate for sure.

Probably recommendable to wait and see what the experts around here have to say also. :D

 

[wobbly goblin]

think most of the experts are out grabbing sammiches
5-16-14? how was there a n+ with that as a fert?
rox..roll with it...you seem to have a clue

fwiw

 

[MrBlackThumb]

I figured it out...

It's a nute lockout caused by the sodium in one of the product I used last week.
The plant showing signs of those deficiencies is the only one I gave the product to.

Everyone else are dealing with Necrosis caused by a Potassium deficiency related to a Magnesium deficiency fueling a Calcium deficiency.

http://www.weedfarmer.com/cannabis/tables_guide.php (Gotta love this chart)

I ended up flushing the locked out plant and watered the others with molasses containing 180g of Potassium and 8% Magnesium/Calcium amongst other useful things.

Hopefully, molasses is gonna be the miracle product that's finally gonna fix the magnesium issues I've been having since day 1.

 

[Seamaiden]

You shouldn't be having Mg issues from day one, it's so incredibly mobile that a foliar using MgSO4 (aka Epsom salt) can green the plant up in a matter of hours.

What's the actual ratio of Mg:Ca that you're working with? That is just *as* important if not moreso.

 

[MrBlackThumb]

You shouldn't be having Mg issues from day one, it's so incredibly mobile that a foliar using MgSO4 (aka Epsom salt) can green the plant up in a matter of hours.

What's the actual ratio of Mg:Ca that you're working with? That is just *as* important if not moreso.

MaxiBloom is the only thing with Mg I was using. It has 3,5% Magnesium in it and 5% Calcium.
What I was spraying them with is something so stupid that I'm not even gonna tell you what it was for my own sake.

Basically, I've never actually fixed my magnesium problem, all I was doing was fixing my calcium issues caused by the lack of Mg.
So, for the past two months, my plants have been Mg starved and unfortunately, I learned about it 1 month before harvest.