What Is Wrong With My Amazon Sword...

[VidVid]

Hey... ive just noticed a week ago one of the leaves on my amazon sword turning yellow, then blackish as the days go on (as seen below)...Is it a particular nutrient or light deficiency (presently have 1.6 w/g) ??? I place root tabs on all my plants, with weekly liquid dosings and after noticing the yellow blackish i stuck in another root tab right under the plant...It has not got better eversince...I have also heard from another forum that if its the outer leaf of the sword?i dont have to worry because older leaves do die off occassionally and i should just cut it off from the base? If it is an older leaf, does that mean my sword is fully grown (its currently at 8 inches from base)???
Thanks again for any replies...
P.S. In between the wisteria and the amazon is some sort of chain sword (anyone know the exact species?), is their any special requirements i need to know about it???

 

[Themuleous]

Yeh looks like some sort of deficiency. What liquid fert are you using? It could be that the leaf is getting old, are any of the others affected or got holes in them?

Sam

 

[VidVid]

im using phosphate free Aqua Master Plant Food - It contains N, P, K (2.6, 0.5, 0). Chelates of iron , Copper, Manganese, Boron and Zinc. I also used the jbl 7 balls (the one lasting a year) which i placed a few months back...Now i replaced the balls with another brand of root balls which similar to the liquid fert used, also provides essential nutrients and tace elements necessary for lush feshwater plant growth.
The other leaves seem fine, as you can see in the picture its just that only one leaf is majorly affected and i have come to realise that if its some kind if deficiency, then why is it only affecting one leaf???
Thanks for any replies.
P.S. The really young leaves shooting up have like blackish veins but as they grow, ive noticed that they disapear gradually and turn green...Is this normal???

 

[danski]

maybe like he ^^^^ said its getting old.all the rest seem to be fine.leafs do get old and start to rot away.i would think about cutting it out.pruning does a plant good.they start to grow more to replace lost leafs.if you cut it out cut as close to the base as possible so you dont have a stem sticking out.

 

[Liam]

The plant looks healthy, a leaf or two on the outside of the plant dieing is nothing to worry about just pull it off at the base of the plant. The leaves can get as long as 12 or 14 inches and the plant can get much bigger. A deficiency would show on all the leaves especially new ones. Yeah the veins show more when the leaf is young.

 

[Griz]

I agree with Liam, it looks like a very healthy plant and it sounds like you're doing everything right. I would just remove the affected leaf. I regularly trim the older leaves off of my swords. Keeps them looking good and encourages new growth.

 

[VidVid]

Ok thanks...il give the leaf a trim as i do my next water change.