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White & yellow leaf spots

Steve Green

New Member
Hi all, I'm new to the sites and am reaching out for some help.

I'm on my first grow and things are mostly going really well. I have a single plant, it's a seed a friend bought from Amsterdam a few years ago. Allegedly og kush.

I'm in my second week of flowering and the pistils are coming through great. The plant is quite heavily super cropped and has a beautiful canopy going with loads of tops.

My setup:

80x80x160 tent
Dwc top feed with clay pebble medium
Mars 700 (drawing over 550w when full spectrum)
Gh flora series nutes plus koolbloom
6 in exhaust fan
Clip fan running across canopy, not oscillating. Small usb fan blowing air under canopy.

The conditions
Temps generally sit around 20-23 Celsius at lights off, 22-26 lights on
Ph ranges between 5.2-6.1, after my last reservoir change 2 days ago is now at 5.5
Nute mix at about 50% recommended and somewhere between transition and early flowering mix on the feed chart. (trying to gradually increase p&k.
Reservoir holding about 19-20l
Ec 1.2
Relative humidity always between 40-50%.

So last night I topped up the reservoir with a Nute mix of a ratio of 3ml gro, 5ml micro, 5ml bloom and 3.5ml koolbloom in 4ltr (just over a us gallon) pH to 5.8 and added half to the reservoir. I also pruned a few lower bud sites, maybe 4 to be precise as the plant is super bushy and they'll never reach the light.

I woke up this morning (end of light period) to find a number of leaves with white/yellow spots on them. The plant seems healthy otherwise, the growth and stretch is noticeable but the nodes are still pretty close on the main tops. There also seems to be some tip burn so maybe I'm a little heavy on the nutes, as I was trying to slowly increase p&k. The discolouration looks like it could be leaf septoria or the dreaded spider mites, based on what I can find online. However I can't see any sign of any pest on the back of the leaves but I don't have a magnifying glass so can't be sure. I also noticed some spots on the main stem but that seems to be mostly in the areas that have recovered from the super cropping.

I only had a short time before lights off so didn't get many pictures, I did pluck a couple lower leaves with minor spots and have added pics of these. I will take more when the lights come on.

Thank you!

Any help on what it could be? Some suggestions on what steps I should take would be great too. I'm thinking just change the reservoir and start again with a lighter nute mix. Amy feedback on the overall setup would be welcomed too :)

Steve Green

New Member
re: White & yellow leaf spots


I uploaded some pics of leaves I plucked but not sure how to link to the post, can you see them in my profile? These aren't the most heavily affected but it shows a couple spots. Some of the other leaves are showing bigger spots or a more speckled appearance.

Thank you!

Steve Green

New Member
So after the dark period the issue didn't seem to get any worse. I can't see any sign of pests but bought a neem oil mix spray just in case, still deciding whether I do a preventative spray just in case as I'm only in the second week of flower.

I suspect the issue was more a nute/pH one. As I started to drop the grow (N?) nutrient and up the p&k and the pH was sitting quite low after the recent change (5.5 after it was naturally sitting at 6.2 prior to the res change) it may have cause a shock or lock out. I was advised by a friend that the pH in flower actually needs to sit a little higher, around 6-6.2.

So what I am doing:

24 hour flush with tap water pH to 5.9 (tested this morning after 8 hours flush - pH 6.1, ec gone to 0.2)
Will make a new nute mix when lights come on and pH to 5.9-6
Monitor for pests, possibly spray with neem mix as preventative measure (thoughts on this?)
Be really careful not to go from my outdoor garden to indoor to minimise chance of bringing nasties in with me.

I'll attach some pics of other affected leaves, please let me know what you think.

Steve Green

New Member
Okay then, talking to myself here but I'll keep going in case someone else might get something out of my experience :)

I changed the res with a nute mix 85% of the week 2 bloom mix from a gh feeding chart I found in the forums. It was 3ml grow, 7ml micro and 12ml bloom. I backed off the liquid koolbloom for now as I was reading it should be added 4+ weeks into flowering (anyone have experience to share on how I should use this?), plus I think the 12ml of bloom should give the mix enough p&k for now. She showed some signs of nute burn within a few hours so I topped up the res with pH water. Seems to have balanced things when I checked 5 hours later just before lights out, as I checked the pH and ec which are sitting at pH 6.1 & ec 1.5. I will just top up pH water at next lights on and see how the pH ec are going.

Going away for 4 days so hoping I can get it balanced, any tips to share on any of this would really be appreciated.


Well-Known Member
First of all, amazing detail and photos in your help request.

Second, great job catching it this early. The really tiny white dots are from mites. I saw a few baby ones on underside of leaves. Neem oil will take care of them. I have ongoing back and forth going right now, but they never get far enough to do any damage any more. You'll be fine, especially with healthy leaves like those. Do a spray now and follow up in week even if you don't see more mites. Then only if you see mites. It's safe to use right up to harvest.

Larger spots may be from water splashing on leaves. Under strong light the drops cause lensing that burns leaf. No sign of any other stress or nute problem.

Steve Green

New Member
Thanks so much for the reply. I was a bit hesitant to spray as the flowers are developing noticeably every day (exciting stuff for a first timer!) and wasn't sure how it would affect them. I'll give her a spray tonight. As I'm going away for a few days I'll be leaving the light on the less intense bloom setting so shouldn't burn the wet leaves too much. Quick one, is it okay to spray while inside the tent? I would think getting it all over the tent walls would be okay and take care of any stray eggs.

I think you're right about the larger spots, as I'm working in a small tent I often get nute mix on my fingers when testing the res so could easily have touched the leaves after.

Lastly, do you think I'm on the right track with my nute mix (especially use of liquid koolbloom) and pH?

Thanks again brother, anything I learn I'll be sure to help others with.


New Member
Hi Steve,
Just like the KingstonRabbi said you got in early, always try to anticipate. I use Eco Neem Oil on the girls outside and inside and at times have been quite liberal with it and never once has it caused me any problems other then keeping the bugs away. Use it nearly everyday outside and would be lost without it. Your girls are looking fine m8 [emoji106]

Sent from my iPhone using 420 Magazine Mobile App


Well-Known Member
I'm a soil grower so can't advise you on nutes other than nitrogen may be a little high. 2 weeks into flower not a problem, and you said you were tapering off I think. If kool bloom is what I think it is you want to wait until bud set, about 4 weeks in like package said. First few weeks plant needs to focus on establishing buds to be ready for swelling and pumping out resin for rest of flowering. If someone who does hydro says otherwise go with what they say.

Steve Green

New Member
Thanks southernbuds, I'll give her a solid spray :)

Thanks again Kingston, the next week feed chart I'm following says to halve the grow nute so should bring the nitrogen down. The advice is good regardless of lack of hydro experience. I think I'm on the right track.
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