Magnesium deficiency?

shiva71

shiva71

Well-Known Member
Hiya,
This is a FastBuds strawberry banana auto under an enhanced spectrum QB288 in DWC. PPM is about 700 and ph 6 - 6.5. Very obvious yellowing of leaf tips, to em it looks like Mag deficiency, do you agree? Ive been feeding her epsom salts but perhaps i need to give her more?
Any thoughts?
Thanks!
IMG_20240406_193419.jpg
 
shiva71

shiva71

Well-Known Member
HydoDan said:
Doesn't look like mag def.. Looks more like light burn.. Is it happening lower on the plant?
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Its definitely on the upper parts of the plant. IR thermometer reads about 74° at canopy, is that enough to cause light burn? That part in the picture is about 40cm from the light.
 
Drop That Sound

Drop That Sound

Well-Known Member
The affected leaf tips won't really recover all the way, and it might take a few days or a week for the plant to re-adjust. Light stress and heat stress are 2 different conditions, but sometimes go hand in hand. Keep an eye on the new and upper growth that it isn't preying to escape the light, or twisting, bleaching etc., and don't expect overnight results. There's a hot (bright) spot under your panel, and it for sure looks like stress. Otherwise they look good, and you aren't really pushing the EC too high.. so yeah.. Would be better if the panel was more spread out for even coverage. Otherwise you gotta do what you gotta do, and raise it up more if you have to. You might even want the canopy to get a little bit warmer using LEDs (75+), which seems like a backwards approach when dealing with light stress, but leaf temps during the day are important to how well the plant transpires, and transports mobile nutrients, etc.
 
C

cage

Well-Known Member
shiva71 said:
Raised the lights and dimmed them but seems to be getting worse. Yellow tips everywhere :(
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At the beginning it definatly wasn't magnesium deficiency.

You have too much nitrogen, the overly green look and tips curling down.
Yellowing of the leaf tips and margins is a a sign of potassium deficiency, which you have made worse if you have been adding calcium or magnesium since they compete with each other.

Ratios around 4:2:1 for K:Ca:Mg could be used as starting point depending on growth phase.
 
shiva71

shiva71

Well-Known Member
Hey doods thanks so much for the help - probably my 8th grow but still keep having issues!!
Ok so noone things its Mg deficiency. Overnight ppm went from 850 to 900 so i guess nute burn is also a possibility. Ph also went up from 6.3 to 6.7. I have 3 of the same strain they all seemed happy about 750ppm but i kept trying to throw more at them and none have liked it.
Topped up the rez gave her one part of Canna Hydro Vega which is 0-3-4 cus yeah probably some N issues and a bit of calmag. 750 but with the ph down 780.
Also something i noticed some of the tips are curling up
IMG_20240408_111603.jpg
Lights raised and dimmed, heres the whole plant this morning, i mean shes not looking so terrible i hope with the lower ppm and raised lights shell pull through...cheers guys!
IMG_20240408_111610.jpg
 
shiva71

shiva71

Well-Known Member
coreywebster said:
What ppm scale are you using ?
What does it equate to in EC?
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Ummm...haha you ain't gonna like this, I don't know what scale, it's whatever my Milwaukee probe is set at. And in some ways it doesn't really matter, if the reading (whatever scale it is) goes up, then the plants not feeding and it needs to be lowered; if it goes up she is feeding and it can be raised slowly. I just work on those principles. I calibrate it with 1413 solution and I know my tap water is about 170ppm these are my references.
 
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