Please help with very yellow plant

[instink]

Hey guys. I have this one plant which is VERY yellow. and only on the canopy. Below the top leaves she is nice and green. I also have another 2 plants which are all identical (from the same mother) and they are fine and green, no problems at all. They are in soil

 

So basically I have 3 plants, all the same, all being fed and watered the same, yet one is massively yellow on the canopy. She is also the closest to the light but I moved the light further away, temps are fine (23 degrees at the top leaves) and its been like 2 weeks and still no improvement....

 

 

Thats about a week ago, since then she has got a bit worse, when I get the digicam back i'll take some more pics

 

This is really bugging the hell out of me and I can't seem to get an intelligent answer out of ANYONE, it is SO frustrating. I have tested the ph runoff from the soil, its fine. I have tried flushing, I have tried half-feeding and full feeding

 

From what I have read of nute deficiencies (no pictures I have seen seem to match up to this) it could be potassium, but thats just a guess. She is 4 weeks into flowering

 

Please someone help me as i'm getting desparate, I don't want this to affect bud development obviously... I just want her to be as healthy as all my other plants, cause she is the biggest!!

 

Thanks... if you need any more info just ask, I'll be happy to answer. thanks!

[Guest Eikel]

Hi Instink,

 

Your pics definately show a deficiency rather than burn or anything like that (based on what I've seen with my plants anyway). The leaves still look quite healthy, they're just losing their colour due to redistribution of nutrients to other parts of the plant.

 

If I were you, I'd try "swinging" my ph a bit, it worked great for me when I had a Magnesium def with my plants, drop the ph and more magnesium becomes availabe. With your situation I might start with a ph of 6.5-6.9 to increase the NPK levels available to the plant while reducing the iron and Mn (what's that one again? forget) levels.

 

This chart from Ferengi420 has good information about ph and levels of elements. I use it quite often to treat deficiencies rather than adding "extra" levels of something and burning my plants with too strong nutes. Remember to look at the Soil, not Hydro charts, the medium changes the distrubtution of the elements dependant on medium.

 

Hope this helps!

[instink]

Thanks, I'll give it a go. someone also suggested iron def, how can i add extra iron?

[Guest Eikel]

Just mix your typical nutes at the strength you've been giving them and follow the ph chart to where more Iron (Fe) is availble...

 

So if you think it's an iron and not a potassium or nitrogen def, you lower the nutes to around the 6.0ph mark. That makes more iron available to the plants.

[instink]

Der i should have thought of that. Thanks again

[Guest Eikel]

Also, these things may take time to work...

 

My plants took 2-3 days to fully get over the magnesium def they had so persist with your treatment (whatever it is) for at least a couple of days to make sure it has an affect, unless they start to die that is.

[WantDaChronic]

click the sick plants link in my sig, might help :smoke