Leaf Chlorosis Overnight?

[Coronel]

Hi this is part of a small set of clones i am treating
Initial symptoms see here

This one was responding very well to foliar epsom salts and was repotted 10 days ago in a mix of worms castings, vermiculite and peat moss (the peat is a garden bag that comes with with fertilizer)

The only thing that changed is that since 2 days ago it is very cold outside and in the night the temps in the garden space go down to 7 degrees C.

Yesterday only the small leaves in the bottom showed some damage (that is old and has been in the plant before i got it)

This morning i found this leave went chlorotic.

The bottom "branches" are not developing at all, but the leaves are not yellowing anymore.
The tips look burnt but it is also old damage.
The intervenal space is clear but the veins are darker.
There is two tips by the top that have been putting out new grow (the small tips that are at fan leaf level).

The runoff pH is in the high 6 (6.7 to 6.9)
Has had two watering with a solution for vegging (Bio Sevia grow 4ml/lt) + Bio roots (2ml/lt).

The soil looked too wet but the plant doesn't look over-watered, the fan leaves point up for the light.
I watered this morning with h2o2 30 vol diluted at @4% to add O2 to the root zone and added used dry coffee grains to try and absorb some of the excess water.

When re-potted the root looked good. These clones have been rooting since early november and have a nice root mass.

 

[cannabeans]

The first pic looks like light burn...
the PH seems a bit high too... try bringing down to 6

 

[Coronel]

The first pic looks like light burn...
the PH seems a bit high too... try bringing down to 6

If you look at the picts where you can see the whole plant you will realize it is the big leave that is the lowest and farther away from the lamp.

Also it is the leave that went from green to that overnight... not even whole night i looked at the plant at around 1am last night and was all green this morning at 6am was yellow like that...

With the amount of peat and coffee grinds the ph should drop in about a week.

 

[cannabeans]

With the amount of peat and coffee grinds the ph should drop in about a week.

You may not have a week to wait for that to happen...

 

[cannabeans]

 

[Bulldog420]

Did it get really cold? That looks like frost burn. Just a guess.

 

[Coronel]

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i know your intention is to help, you seem to point to a excess / deficiency of K or S....
but if you read the symptoms you pasted it matches both def and excess ok K can you develop what is your point?

You may not have a week to wait for that to happen...

pH should never be adjusted is a single go.

Also this is new soil and both the peat and worm castings are slightly acidic, and the water is 7 thou it is buffered a lot i think this is why the runoff comes 6.7 but there are many other plants in that mix and they are doing well.

 

[cannabeans]

I am just tossing ideas out there to you...Good luck!

 

[Coronel]

Did it get really cold? That looks like frost burn. Just a guess.

well the thermometer slept on the pot on top of the soil and registered 7C but outside was -4 that leave is the farther away from the lamp and might have been getting very cold intake air from the fan?

btw i just checked the pH with different drops (a 3 to 10 kit) and got:
pot soil + distilled water =5 to 5.5
pot soil + tap water = 5 to 6
soil from the bag + distilled = 5 to 5.5
(difficult to decide in a color)

So the tap water brings slightly up the pH but still in desired range for soil...

 

[Coronel]

I am just tossing ideas out there to you...Good luck!

Thanks bro, i like the picts with symptoms you posted, and going to keep it even print it for off-line diagnosis.
it is just that i had been looking since this morning at several sites with the leaf diagnosis charts and doesn't matches a single one, but a mix of several...

 

[tinderthumbs]

that is sooooo cold cant believe there was any life left n it at all

 

[Coronel]

that is sooooo cold cant believe there was any life left n it at all

You will be surprised i have 2 flowering in an unheated room with a meager 150W HPS and that is the only heat source, they are smallish for their age but doing very well, lush green and vibrant with smallish colas growing happily.

The darker one is a Northern light #5 x Haze (sister of the mother of the diying clones)
The clearer one is a Sensi Skunk (the 1 female out of a 10 seed blister offered when bought the NL5H)

From 15 to 7 degrees C the plants slow down but dont suffer.
Under 7 damage can happen specially if sustained for long enought as to cool down the rootball

 

[Coronel]

Just an update, after 2 days of freezing temps outside, out of three clones 2 developed this yellow leaves.

The damage was apparent but they didn't yellow straight away, now the yellowing is progressing from the damage to the rest of the leave (I think the plants discarded those leaves are moving the nutrients out)

An oil heater in its lowest setting with a fan blowing towards the clones was tried and seems to help.

The clones are in a humidity dome even thou they have a good root system now, they come from a grow-tent that is like the Mojave desert in summer at noon.

Now to illustrate quite the opposite here are cuttings of the ones that are in a really unheated place (the ones from the picture just above), both taken from the bottom of the plant where the buds were the least developed.

It is very strange to look at the microscope. There is resin and trichs everywhere but it is my feeling that they have not yet stretched and the bud is not developed yet.

Remember these ones have been in flower for around 2 months but under extreme cold with a 150W hps.

The few pistils visible are white, the trichs are mostly whitish (thou it might be the light from my scope.

It was decided to take cuttings so late in flower 1st because of the under-development shown, 2nd i don't trust the clones from the hot plant and after testing i would like to have this strain propagated as much as possible in my city hehehe...

 

[DrMcSkunkins]

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Theres a much higher resolution copy of that chart in my helpful charts link.

 

[Coronel]

Theres a much higher resolution copy of that chart in my helpful charts link.

Thank you!

I was trying to find the will and time to look for it on the net you saved me from that :P

Many interesting charts in there too! a must read, bookmark, visit, passtime!