Leaves curl up and spots on leaves

A

Afghan Kush

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Hello guys,
I hope someone can help me out. I decided to grow a few plants again after a long break (10 years) so I am pretty much starting from scratch.
Unfortunately this grow is not going as smooth as my last grows so I need some help.
My leaves are curling up and I am getting yellow/rust colored spots on my leaves. My plants just don't look good, I think I have a PH problem which results in a Magnesium deficiency.

Here are some details:
I am growing on soil, COMPO Bio-Universal soil
Temps are usually 26C to 30C (78.8F to 86F)
Fertilizer is BioBizz Grow (only given once about 2 days ago)
Strain is pure Afghan, 4 weeks old

Now more info about the problem.
First I noticed my leaves curling up and I thought that it was heat stress but now my leaves are getting those yellow/rust colored spots and I think that I have Magnesium deficiency.
So I went to the pharmacy today to purchase PH test strips to test my water.
My tap water has a PH of 7.2 maybe 7.4 and I have been watering with that for the past three weeks. Now that I know that my PH is a bit too high I have added 1ml of Vinegar to 2L of water today to lower the PH to 6.8.
I am planning on lowering the PH to 6.5 the next time I water my plants and keep it there.

Here are a few pictures of the lower leaves, do you think that my diagnosis is correct?
Thanks

EDIT: Forgot to add, plants are 4 weeks old.


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Growdude

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your PH is definitely high, the last pic looks like heat stress.

Measure the PH of the run off and adj so that is ~6.5
 

Alistair

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Yes, the last pic looks like heat stress to me too.

It's a good idea to buy a digital meter. A lot of people find that those pH test strips aren't all that reliable. I for example, used to use to pH test drops, and after purchasing a digital pH meter, I discovered how inaccurate the drops were.

I forgot to mention the water that you're using. Often times tap water has too many salts in it for healthy plant growth. Salt build-up in the soil is also a source of nutrient lock-out. Reverse osmosis water is good for plants. Some people like distilled water too.
 
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the spots look the begining of a mag def
do u have any bugs? looks like thrip damage a lil 2
 
A

Afghan Kush

Guest

Thanks for the replies.
I don't have any bugs besides those damn flies. I have setup two of those yellow sticky traps and I am spraying Neem oil onto the surface of the soil. This seams to keep the flies in check since I only see two to five at a time.

I water with tap water filtered through a Britta Water filter because my tap water contains a lot of calcium. Unfortunately I forgot to take a PH reading of the run off but I will do this when I water again in two days.

At first, I was thinking heat stress as well but then those spots appeared on the leaves and only the bottom leaves curl up which are further away from the lamp. I am running a 250W inside a CoolTube. Unfortunately I can't do much about the heat since my apartment is right under the roof but I always keep by bulb far enough away to keep the temps around 26-28C. Sometime they hit 30C but not often. Winter is around the corner so temps will go down soon.

I am trying to avoid purchasing the digital PH meter since I have never needed one before. Once I know what is going on I can pretty much repeat what I am doing and everything will be fine. I also have one plant which seams to be OK with the temperature since its leaves don't curl up.
I have three Afghan, all of them have spots on the leaves and two have leaves curling up...... maybe I have two problems. One is heat stress and the other Magnesium deficiency.
I'll go ahead and order something to add Magnesium and see what will happen.
 
I

IRISH

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ok AK, gotta tell you, gd and ay gave you good info. i'd be looking at the ph more than adding something to alleviate the problem...

those test strips suck. you say the tap is 7.4? i'd be willing to bet it's prolly more like 8.4-8.8. i tried to balance mine to 7 , then with digi, and it was 8.2...:eek: ...

man, i'm telling you, a digi ph meter ain't but 35 including shipping from ebay.

gotta take a closer look at the ph is all i'm saying man...
 

4u2sm0ke

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yep..yep...PH is everything..correct that then see what they look like...Mojo for your grow, and welcome back to growing:D

take care and be safe:bolt::bong:
 
A

Afghan Kush

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IRISH said:
man, i'm telling you, a digi ph meter ain't but 35 including shipping from ebay.

Well I have done a bit of research on PH meters and those cheapies from ebay are not worth the money. They are about as accurate as test strips, so I will go with the test strips for now.

I'll be driving to the pharmacy in an hour to purchase magnesium sulfate. With that and the better PH I expect to see my plants to get better soon.
I'll keep you posted.
 

Growdude

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Afghan Kush said:
Well I have done a bit of research on PH meters and those cheapies from ebay are not worth the money. They are about as accurate as test strips, so I will go with the test strips for now.

I'll be driving to the pharmacy in an hour to purchase magnesium sulfate. With that and the better PH I expect to see my plants to get better soon.
I'll keep you posted.

Dont add anything to correct your deficiency problem, it will only make things worse.
Your PH has to be corrected for the proper uptake of nutrients.
 

HippyInEngland

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:yeahthat:

People underestimate the importance of PH.

PH is the main cause of 99% of peoples problems yet they cant seem to understand paying $30 out will give them 20% extra bud.

We can only advise, if they choose to ignore it, then so be it.

:peace:
 

Hick

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A

Afghan Kush

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All right will do. I'll check the PH of the runoff the next time I'll water the plants. They have been getting the wrong PH for the past four weeks so the soil is probably a bit messed up.

EDIT: BTW I am not saying that a digital PH meter is not a good idea. I am just saying that purchasing one of those Chinese copies is, since they tend to break quickly and drift unless constantly calibrated. This is of course not from personal experience but from numerous reports found on all the major growing forums. If I decide to get a PH meter it will be a Greisinger for about $100
 

Droopy Dog

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Afghan Kush said:
All right will do. I'll check the PH of the runoff the next time I'll water the plants. They have been getting the wrong PH for the past four weeks so the soil is probably a bit messed up.

EDIT: BTW I am not saying that a digital PH meter is not a good idea. I am just saying that purchasing one of those Chinese copies is, since they tend to break quickly and drift unless constantly calibrated. This is of course not from personal experience but from numerous reports found on all the major growing forums. If I decide to get a PH meter it will be a Greisinger for about $100

Good thinking, quality tools aren't cheap!

The combo meter we use at work runs right at $750 (Myron L Ph and EC), so how is a $30 knockoff going to compare? I can have an old one but it's $350 just to have it rebuilt.:holysheep: Can't swing that, but something in the $100 range is doable.

I use test strips at home for a down and dirty reading :hubba: then take some solution in to recheck on the good meter. The strips aren't as accurate, but gets you in the ballpark. Also, if you can get strips from a printing supply place they tend to be better quality than what you would get at a pool supply.

DD
 
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