Light stress?? Please help diagnose my plant issues!

[greenman12345676543]

Hey all, at my wits end with trying to figure out what is wrong with my ladies any help or advice would be massively appreciated

Im running Athena nutrients, two feeds a day in 3 gallon pots with 10-15% run off. Coco perlite mix 70/30

Ph is 6~ and 3 EC (as per Athena guidelines) while run off is coming out at 3.5-4.2 EC and ph is 5.7-6

LED lights are roughly a foot above the canopy

It started with the tips of the fan leaves going yellow and turning upwards and slowly progressing throughout the rest of the leaf. My environment is about spot on (I think) 25 degrees Celsius/ 77 F, with the humidity at 51~

They are at the start of week 3 and the yellowing is progressively getting worse

Cheers

[golfnrl]

Your grow conditions sound good. I'm assuming these girls are fem photos? What kind of light are you using? Are you following the manufacturers recommendations for how high above the canopy the lamp should be at this stage of growth? Have you checked out the Plant Problems button at the top of this page?

Fans are solar panels, right? The plant stores energy in them and uses them as needed. As the stored energy is used up the leaf yellows and dies. That could be what you're seeing.

What's you're plan on defoliating? The plant in #2 looks like it might need some thinning out in the middle and down low.

[greenman12345676543]

Yep fem photo. Im running 4 seasons 200watt Leds and if anything im giving more space between the light and canopy as directed by the manufacturer.

I generally defol after flip and then again around week 4 but have somewhat left these alone as i dont want to stress them out anymore than they already are! ;(

[dirtymike]

Checking run off you will get alot of different readings. Flower's are demanding more nutes so it takes it from the fan leaves causing nute loss in some of the leaves. You have burnt tips on some of the fans also, my guess it to much love.

[greenman12345676543]

What exactly do you mean the run off will give different readings? So if im catching what your throwing then decrease the nutrient levels and see how they react

[Bluey]

It's nute burn. Reduce EC and suppliment with ¼ to ½ strength PK. Increase fertigation to 3 times or 4 per day. Pots are small and will be tough to manage moving forwards. Increase pH in a range to 6.25 averaging 6.1 slowly increasing to 6.2.

Reduce light output marginally to make it easier to manage

[greenman12345676543]

Thanks for the reply Bluey. By tough to manage moving forward do you mean i need to increase frequency of feeds and itll be alright or are you referring to something else?
The increase in ph will mean the nutrients theyre lacking will be easier to uptake? Or am i way off - 6.2 seems slightly high to me

[Bluey]

Your plant will uptake calcium best at 6.2 and above.

At 6 it won't be taking up much if any cal in coco.

Vary the pH as I said and you should be right

[9fingerleafs]

Magnesium deficiency and the EC is too high. I explained in the other post

[9fingerleafs]

I would lower the EC to 1.5 and then add magnesium. Maybe epsom salt. Maybe even one big flush with the right ratio of nutrients but I don't really do that myself. Then when the leaves recover some pk boost could be added around week 5. I don't really monitor pH too close. I always aim for 6 Ang got my own environment dialed in. Maybe because the runoff is lower some increase will help balance out but I don't think it's the main issue. The EC is too high and the tips of the leaves are burning. That means toxicity of some nutrients preventing others from being absorbed. That itself could create an accumulation of nutrients in the medium lowering the ph. So low runoff ph it's a symptom not a cause in my opinion

[Bluey]

I agree. Get EC to under 2.0. 1.5 would be good and adjust from there watching new growth.

I also agree right now may be a week or two too early for PK.

I don't know which method would be best for dealing with the calmag def but I think both would work combined with the drop in EC. Your method probably quicker.

[greenman12345676543]

Awesome, really do appreciate the feedback. Thanks you two, might just be salvageable yet

[OldManGrower]

Raise your PH, add additional cal-mag, cut your nutrients. You have nutrient burn due to low PH causing nutrient lockout.

[greenman12345676543]

Cheers Oldmangrower that seems to be the general consensus. Hopefully not too late for them to recover

[Radeon]

I don't know. I zoomed in on that first pic and it looks like there are a lot of trichomes and a couple flowers look like the pistils are turning yellow. I wouldn't do anything if it were my grow. I'd just keep watering and see what happens. Too late in the game now. I agree with dirtymike, they are taking food from the fans. It's already begun, just let it play out.....

[greenman12345676543]

Cheers Radeon appreciate the input. Fingers crossed they bounce back

[golfnrl]

Let us know how it works out