Yellowing leaves - experts needed!

stark

stark

Member
Hey all

First post so please forgive any stupidity.

I've searched the internet for hours to find leaves that look like this with no luck, so if anyone out there can help I'll love you forever.

I've been growing 2 varieties - LSD and Red Dragon, both from feminised seeds - in a growtent with a 600w HPS and 3 fans (1 intake, 1 circulation, 1 outtake) for about 6 weeks. Same conditions for all 6 plants.

Aside from the fact that I think I was underwatering them for about a month, I have a problem with the LSD. It seems perfectly healthy apart from the fact that the leaves are yellowing (yellow leaf picture attached). New growth is vigorous and very green, and the smaller very bottom leaves are also green. It's even put out pistils in the last couple of days (oh, I hope I'm not seeing things). The Red Dragon seems ok, but has a small touch of the same sort of yellowing.

I've done the hand-test for heat and the light doesn't burn me (it's about 18 inches away), the soil is Plagron Royaly Mix, and I've started watering with correctly diluted Canna Terra Vega in the last week or so. Is it a nutrient problem? I haven't kept a diary so can't be sure when the yellowing started.

I think that's everything. If anyone knows what's happening and how I can fix it, you're welcome at mine for a smoke anytime (assuming my plants make it, of course!).

Thanks.

And anyone got any ideas what happened to the little guy on the middle right (mangled picture!)?
 

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cee1230

cee1230

Well-Known Member
wow my plants were looking just like that. i could not figure it out.i started out usin mg and it tore my plants up it killed 6 of them.the 4 that made it through started to look good and then i got the same yellowing like u have. i transplanted to bigger pots and they started to look better. check my thread https://www.rollitup.org/newbie-central/243335-first-grow-will-work.html . i would recommend a transplant the roots are prob cramped. but im no pro
 
brasmith

brasmith

Well-Known Member
http://www.icmag.com/ic/showthread.php?t=11688

Scroll down till you find the ZInc section and take a look at the pic.


Zinc (Zn) Micro Nutrient and an Immobile element.


Zinc plays a lot of roles in the plants, first off zinc aids in the plants size and maturity as well as production of leaves, stalks, stems and branches. Zinc is an essential component in many enzymes as well as growth hormone auxin .Low auxin levels can be the cause of stunting of the plants leaves and the shoots. Zinc is also important in the formation and activity of chlorophyll. Plants that have a good level of Zinc, can handle long droughts. So that’s why Zinc plants an important role how it absorbs moisture.


Zinc deficiencies on some plants will have the Spotting and bleached spots (chlorosis) between the veins first appears on the older leaves first, and then goes on to the immature leaves. It will then start to slowly affect tips of growing points of the plants. When the zinc deficiency happens so suddenly, the spotting can appear to be the same symptoms to that of an iron and manganese, without the seeing the little leaf symptom.
Zinc is not mobile in plants so the symptoms will occur mainly in the newer growths. Having a plant that is deficiency in Zinc can cause small crops, short shoots and have a cluster of small distorted leaves near the tips. Between the veins (Interveinal) yellowing is often combined with overall paleness. Pale or grayish, yellowing between the veins; rosetted weak is the signs of a Zinc deficiency.
With a low level of zinc in your plants, your yields will be dramatically reduced.
Interveinal chlorosis is present in the small, narrow distorted leaves at the ends of really shortened shoots and the shortening between internodes. Leaf margins are often distorted or wrinkled. These nutrients will get locked out due to high pH: Zinc, Iron, and Manganese. These deficiencies will often occur together. Parts affected by a zinc deficiency are young leaves and petioles.

Having an excess of Zinc is very rare, but when it does happen it can cause wilting and in worse cases death.
 
stark

stark

Member
Thanks for that - that's a good page! Clearly you know more about this than me, but the leaves in the pics still have colour around the edges - mine seem to lose colour completely from the tip inwards. But if you're saying it's definitley Zinc I'll pop out and buy some galvanised nails!
 
brasmith

brasmith

Well-Known Member
The pic displays a minor zinc problem and your zinc issue is more advanced because it is starting in on the new growth too. How is your PH? Does your nutirent system have zinc or is it just the basic npk?
 
stark

stark

Member
I was kinda joking about that - but I did read it somewhere today as a fix. Arguably not the most scientific method though...
 
stark

stark

Member
brasmith said:
The pic displays a minor zinc problem and your zinc issue is more advanced because it is starting in on the new growth too. How is your PH? Does your nutirent system have zinc or is it just the basic npk?
Click to expand...
In that case, thanks and please forgive my impertinence. :dunce:

The PH test I have looks like the children's version, so I can only tell you approx 7. This is too high methinks. I'll get a new one tomorrow and tell you exactly.

The fertiliser I'm using is 3.1.4 and contains many other trace elements etc, but Zinc is the smallest in quantity of all these.

Is there an easy fix for this? And will the leaves regain their colour or is it game over for them?

Thanks again for your help on this.
 
brasmith

brasmith

Well-Known Member
stark said:
In that case, thanks and please forgive my impertinence. :dunce:

The PH test I have looks like the children's version, so I can only tell you approx 7. This is too high methinks. I'll get a new one tomorrow and tell you exactly.

The fertiliser I'm using is 3.1.4 and contains many other trace elements etc, but Zinc is the smallest in quantity of all these.

Is there an easy fix for this? And will the leaves regain their colour or is it game over for them?

Thanks again for your help on this.
Click to expand...
Bring the ph down to 6.5, that is optimal for your plants. When the ph is either too high or too low other nutrinets can reek some havick on how your plant utilizes other nutrients. Your plant's ability to uptake zinc can be compromised by other nutrients that get in the way and blocking out the availibility of zinc.
 
stark

stark

Member
brasmith said:
Bring the ph down to 6.5, that is optimal for your plants. When the ph is either too high or too low other nutrinets can reek some havick on how your plant utilizes other nutrients. Your plant's ability to uptake zinc can be compromised by other nutrients that get in the way and blocking out the availibility of zinc.
Click to expand...
Right. Shiny new PH pen confirms PH was 7.6!! Have adjusted slightly with PH down - these things need to be done over time, right?
 
brasmith

brasmith

Well-Known Member
stark said:
Right. Shiny new PH pen confirms PH was 7.6!! Have adjusted slightly with PH down - these things need to be done over time, right?
Click to expand...
No they can handle it go ahead and on your next watering bring it down to 6.5. They will be fine.
 
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