Nute burn or mag deficiency?

[talkaboutj]

Not sure what is going on here, possible nute burn is my guess but maybe mag deficient
Only happening on 4 or 5 plants so far, 1-2 leaves per plant about halfway up. Top and bottom leaves all look healthy.
Last watered 3 days ago with dyna gro.

Mr Nice guy
Ocean Forest
Dyna-Gro
Ph6.5-7.0
1000w
2.5 weeks since clone transplant

24/0

 

[Kriaze]

Hello and welcome to
Judging from what I can see the plant is suffering from heat stress, you can see this by the canoe shape of each finger of the leaf. Now I would have said that the discolouration was light burn at first because of this but I note that you mentioned they're only on the middle leaves and they would definitely be more pronounced closer to the light if it was light burn.
If it was a magnesium deficiency I would expect the discolouration to be on the lower leaves first and also be much more pronounced there. It's also definitely not nute burn, that would affect all leaves at the tips. This can only lead me to think of problems with PH.

If your PH is too low it will miss some vital nutrients and likewise if it's too high. Are you testing your PH after adding your nutes and trying stay around 6.5? If so then it may be worthwhile calibrating your meter to check that it is reading correctly as this problem looks like PH fluctuations after working through the other possibilities.

Bring your temps down first and foremost as the plants are more susceptible to other problems when stressed, then you can check whether it's PH problems and hopefully fix those.

I hope this helps, all the best.

 

[Emilya Green]

I think a couple of things are going on here. I agree with you about there being a deficiency, just not sure it is mag. At the pH that you are watering at, magnesium should be very mobile and easy to uptake. It's symptoms look different than this too, usually involving dead necrotic copper colored spots on the leaves... yours are not doing that.

Check out this chart on the soil side:

This one is a little hard to determine, but at the pH you have been adjusting to, I am pretty sure after studying your leaves for a half hour or so, that you are looking at a copper deficiency. We know it is a non-mobile element that is having trouble, because the problems are not happening at the bottom, but the curious thing is that the new growth does not seem to be affected yet. This indicates that although non-mobile, the needed element does not appear to be critical for the new growth, but is strongly affected on the larger leaves that gather the most light energy. This is where it gets tricky, because boron, copper, iron and zinc all present similarly, but each with some unique characteristics that can indicate the heavy metal that is deficient. The main characteristic of a copper deficiency is that the leaves will turn dark, almost taking on blue or purple undertones. The tips and edges will turn yellow and the leaf will begin to turn under and get stiff. The surface of the affected leaves takes on a shiny or metallic sheen and the leaves most affected will be those directly under the light.

This problem is caused by your pH being above 6.5 and can be quickly corrected in just a few days by adjusting your pH down toward the low end of the scale. Ocean Forest is known for a strong pH drift, and many times a good pH response is found in this soil by adjusting to the low end of the soil scale, or around 6.3-6.4. Accuracy is very important when it comes to pH, and adjusting to somewhere between 6.5-7 is not only too high, but not very accurate at all, with 6.5 being 50x more acidic than 7.0. Get a good meter and carefully adjust to 6.3-6.4 for a few waterings... and I am confident that although the damaged leaves will not come back, the progression of this problem will stop and your buds will be able to start developing again.

After extensively studying your plants, I am not convinced that this is the only problem. I see downward pointing canoeing in some of the leaves in the upper third of the plant, telling me that there is also an over watering problem. Those leaves should be pointing up at that light, but for some reason they seem unhappy. I am curious if this is the case or if the timing of the picture is just simply showing a point of possibly waking up under that big light, but that downward turn of the canoeing strongly indicates to me that you are watering too often. How big are those containers, and how often do you water? Do you saturate the soil each time you water to the point of runooff? And then, how do you determine that it is time to water again?

 

[Kriaze]

Thanks for stepping in with an in depth explanation of what's going on and passing on that information Emilya. It seems I was fairly off track and that happens when newer growers try to help without having a full knowledge of the plants, thanks for stepping in and helping out. If ever you feel the urge for a challenge please, come visit my grow

Apologies to the OP if my information was incorrect, but at least it shook the tree and dropped a golden apple. All the best and good luck with your grow