Weird burns on leaves

[cacti]

Hey guys!

I have four feminized Aurora Indica plants growing in two 50 litre bubblers, under 400w HPS. Two plants on each bubbler. I am now 2 weeks in flowering and one of my plants is starting to show some really weird symptoms. Leaves look like someone poured some acid on them and then they start melting away. This problem only happens to new leaves. Its really weird that only one of the four plants is suffering from this because i use identical amounts of nutrients on every plant. Even with this problem the growing speed seems normal.

Im using GHE tripack with lucas formula and liquid oxygen. pH is allways around 5.5-6 and my EC is currently 1.4. Room temperature is 25 degrees and water temperature is 20 degrees.

It would be awesome if someone could help me out with this one.
Thanks in advance!

 

[Fuzzy Duck]

Its not a burn, burns are caused by nutrient/water splash on leafs under neath hot lights/sun etc

More of a deficiency, we can rule out NPK but would suggest another macro nutrient... appears difficult to pin point which one at the moment as the systoms appear early stage !

 

[cacti]

Thanks for the reply Fuzzy!

Yeah im also almost certain that this is some sort of defiency. Plants are now almost two months old and this problem has been there from the begining. Im scared of putting more nutrients because it might cause overdose for my other plants. Maybe this plant is just totally different fenotype than others and needs different amounts of nutes. I just hope this doesnt get worst.

Can you suggest me some good macro nutrient to try out?

 

[Fuzzy Duck]

Lets look at the secondary macro nutrients and some more of common defeciencys related to MJ.

Ca - calcium, Mg - Magenesium, S - Sulphur which is present in soil & decaying matter.

I don't think its Mg or S.

Ca - calcium, As from you descirption only effecting the new leaf growth.

• Can be caused by excessive usage of potassium or nitrogen fertilizers.
• Maybe test and correct the pH if needed because calcium deficiency is often associated with low pH.

Calcium, an essential part of plant cell wall structure, provides for normal transport and retention of other elements as well as strength in the plant. It is also thought to counteract the effect of alkali salts and organic acids within a plant.

Sources of calcium are dolomitic lime, gypsum, and superphosphate.


Out of interest what type of water is used, whether that be R/O or tap water, hard or soft etc

 

[cacti]

I see. Maybe I'll try adding a little bit of lime and see if it affects at all. Im using normal tap water, but can't say if it is hard or soft.

Maybe increasing pH levels would help because im usually trying to stay closer to 5.5 than 6.

Thanks a lot for everyting!

 

[Fuzzy Duck]

I'm pretty sure you can liquid calcium plant feed, i've noticed Canna do it before.

Adding powdered lime may mess with your PH levels some what.

Might be worth while flushing tank & putting new mix in as short term measure.

I'm also aware that hydroponic system which use a recirclating reserva/water tank as the nutrient feed depletes or water levels get low the PH gets more acidic.

I do find the plant problem strange as its only effecting one plant ? as you suggested it maybe a phenotype/genetic error of partical plant. After all some plant breeders can go through 4 generations of plant breeding in a space of one year... we're bound to throw up the odd rogue seed once in awhile.


By the way you should be able to do a google search on your local water company which should give you details of hard/soft water in you area, i believe you might even get mineral content of water also on further investigation.

 

[cacti]

My water hardness is 0,3 mmol/l = 1,7 °dH, so its soft water then. Yeah I've also noticed pH decrease over time and the lowest pH I've ever been is 5.2 and it seems calcium locks out in 5.4. Ofcourse i have always corrected pH as soon as possible.

This sick plant is certainly different phenotype because its leaves look more like sativa and others look like indica. So the problem might be that this one plant just likes different pH range. I will increase my pH to 6 as soon as the lights are on.

Anyway next time im certainly gonna use cuttings or give every plant their own water tank.