Having Trouble Identifying Plant Health Issue

Ellewood

Member
Hi all - I have two plants that seem to have the same problem. Overall, they both look like they are still in decent shape, but I'm seeing more leaves with symptoms and don't want it to become any worse.
They're both auto-fem Northern Lights and I'm about a month into flowering. The only nutes given was a flowertab - half at the beginning of flowering, the other half two weeks later. It has been 2 weeks since the 2nd dose of nutes.
I haven't been able to
use the recommended amount of light due to heat issues - temp is usually around 80.
The first image is 3 different leaves from plant 1 (it's not very full but flowering nicely).
The second image is one leaf, with close ups of two points.

After looking at images of nute deficiencies I'm leaning towards Magnesium deficiency. Or maybe Potassium or Phosphorus. :?

I'm a newbie, so I'd like to get some experienced eyes to confirm the issue before I do anything.
Thanks for your help - much appreciated!
:peace:


plant 1.jpgplant 2.jpg
 

LizRoll

Member
After doing more research it seems the problem(s) may be high PH and/or light stress. Lights have been on 24/7 since they were seedlings. I also discovered today that one of my auto-fems turned hermie - I'm guessing because I haven't been able to get the temp lower than 80 with the lights on.
I'm going to turn the lights of 10 hours a day and see how things go. My soil PH has always been a 7 - I added a bit of lemon juice to 1 Gal water (testing the PH before and after, not lowering the water's PH more than 1 point).
We'll see what happens over the coming week - not sure how quick they can recover, and with only 4 -6 weeks left until harvest I'll be happy if they just don't get worse.
 

lahadaextranjera

Well-Known Member
P & K def, (also secondaries), absorbed at PH 6.5, most likely to be lockout and feeding every 2 weeks is not often enough for AF's in small pots. AFG's need 18 hrs light indoors.
 

Ellewood

Member
Thanks for the info lahadaextranjera - much appreciated! I think it will be ready to harvest in 4 - 6 weeks. I've read that Ph adjustments should be done gradually so as to not shock the plant. How quickly can I get it down .5 for proper nute absorption? The Ph of my water is about 6.2 (tap water run through a Brita filter and allowed to sit for a couple days for chlorine or other stuff to evaporate).
I had to add several teaspoons of lemon juice to a Gal of water to get the water Ph to go down (6.2 to 5.6). Is that safe to use on my plants or should I use Aluminum Sulfate?
Should I focus on lowering the PH first before I add P & K? Or just do everything at once? Just want to make sure I don't create any new issues.

I'll set the light timer for 18 hours.

Thanks again!
 

LizRoll

Member
I pruned the all leaves that were halfway dead or worse. But there is still tip burn (I think it's from a light being too close for a while) and yellow stems.
The first plant is the one that turned hermie. It's pretty sparse and pitiful looking. But the buds it does have are frosting up nicely.

Plant 1 (Hermie).jpg

Plant #2 - It's more robust and didn't have very many leaves showing symptoms (like I posted earlier) but you can see that a LOT of tip are burned all over the plant. I think that was from the first nute feeding when flowering began a month ago. It's not gotten any worse though.
Plant 2.jpg

Thanks for your help!
 
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