What Are These Small "burned" Patches?

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fliege

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Hello,

I am on my fourth grow. Generally I'm happy with the progress, but I see some odd burned patches on the older leaves of one plant and this is giving me cause for concern. Things are as follows:

* Plants: 3x Northern Lights autos and a 1x Shiva Skunk auto. 2.5 weeks old

* Medium: ~6L pots. Soil composed of a 50/50 mixture of these two:
1) Westland Gro-Sure All Purpose Compost with 4 Months Feed
https://www.homebase.co.uk/gro-sure-all-purpose-compost-with-4-months-feed-10l_p284784
2) Westland bulb planting compost
https://www.homebase.co.uk/westland-bulb-planting-compost-20l_p431147

* Environment: 2’ x 2’ tent using 270 W of CFLs. Gentle PC fans. Currently temps are around 24 C.

* Fertiliser used: Fed once with 1/5th strength Canna Terra Vega Flores.

* Water: tap water. Since around day 15 I have been adjusting the pH down to around 7. Out of the tap it's around 8.5.

* Issues of note: For a short period in the first week I had higher temperatures and the seedlings looked a little heat-stressed. This has improved since then (partly because I finally located my temp probe) and now the tent is at around 24 C at pot level.


Problem
I noticed early on that there were small "burned" patches between the leaf veins on the older leaves of one of the seedlings. Today I saw similar patches developing in newer leaves on the same plant. The other plants seem fine but all maybe are a bit dark green. The leaves on all plants look rather dark green, so I'm not planning to fertilise. I'm concerned about the burned patches. Could the Gro-Sure soil be hot and this is nute burn?

Images

All four plants
Four plants

Burned patches seem to be developing on this newer leaf
Problem developing on newer leaf

These burned patches are on an older leaf.
Oldest leaf with problem
 
F

fliege

31
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What I have done to fix the problem:
At the moment I'm not sure there is anything I can do because I don't know what the cause is. That said, I'm ensuring the pH is around 7 in case I'm seeing lock-out of one nute. I'm also not planning on adding more nutes right now, since the plants all look pretty dark green. I'm ensuring the tent stays under 26 C.
 
SoLowDolo

SoLowDolo

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What I have done to fix the problem:
At the moment I'm not sure there is anything I can do because I don't know what the cause is. That said, I'm ensuring the pH is around 7 in case I'm seeing lock-out of one nute. I'm also not planning on adding more nutes right now, since the plants all look pretty dark green. I'm ensuring the tent stays under 26 C.
Do you add calmag to your water?
 
SoLowDolo

SoLowDolo

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No, I don't. The water is quite hard, if that helps.
I am by no means an expert. But I have seen people on the forums deal with stuff like this. Sometimes an excess and deficiency can look similar. But the first Google image for excess calcium in weed comes up with this... I suppose it's kind of similar
Calcio 1
 
F

fliege

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Well, pH 6.5 is ideal as it's in the middle of the range: 6.0 is the lower end. I was going down slowly from 8.5 so as not to change things too fast. You're right I should now push it a little further down. I've bought an EC meter: surely dissolved salts will be high where I live. I think I will try flushing the plant with the burned spots then water with tap water suitably mixed with RO water.
 
1diesel1

1diesel1

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Give her a bone meal flush. I’m leaning towards phosphorus (P) deficiency. Lower your ph 5.5-6.5.
 
F

fliege

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I'm cautious about adding nutrients right now, and a bone meal flush would do that. These plants are two weeks old and the soil is fresh, so if I'm seeing a deficiency then it must be a lockout. Consequently I think it's best to try to fix what might be causing that rather than add nutrients, especially since I'm not certain which to add. It could be that reducing the pH is all that's needed. Maybe this particular plant is more sensitive to high pH. Does that make sense?
 
1diesel1

1diesel1

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Plants are 2 weeks old. Disregard my last post. Should not be giving any nutrients and ph is not necessary. If you put them in quality soil.
 
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fliege

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Plants are 2 weeks old. Disregard my last post. Should not be giving any nutrients and ph is not necessary. If you put them in quality soil.

That was my expectation going into this, I must say, which is why I'm a little baffled by what I'm seeing. The only reason my current plan is to reduce the pH a little more and fix the hard water is because worst case scenario it does nothing.
 
1diesel1

1diesel1

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Overall the plant looks healthy. Give it a flush till you get runoff then let dry out. Let the soil feed her. She’ll bounce back.
 
crimsonecho

crimsonecho

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I have to say, you’re using a mix with fertilizers mixed in so don’t bottle feed until plant tells you to. Overfertilizing can cause problems like this, because excess nutrients burn both the roots and the plant tissue.
Also over/underwatering causes the same problems. I would just ride it out at this point without doing much. See if it spreads. And be sure to give plain water without drowning them until the medium is empty.
 
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Burned Haze

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If your not reverese osmosis, get your water tested cause that’s prolly why if your ph is correct on your ph. If your using r/o, recalibrate your pen and make sure your pen is correct and I always recommend if your doing r/o every 50 gal’s put 5 gal’s well so you get some trace elements and some micro. Inless your test shows some harsh shit ( mine is 300 , and even high iron but when I do this ratio I have no issues )
 
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