Rust marks on top leaves

[davestampy1]

So my northern light auto has grown great until 2 weeks into flowering. First issue was top leaf edges turning yellow now I have brown patches on alot of top fan leaves. This happened before on last grow. I've flushed it yesterday with phd mag cal. Before this I was phing around 5.7 but decided to increase it to around 6.2 as I read its better in flowering. I'm using gh trio part with a viparspectra 1000. Temps around 25c and 50 percent humidity.

Im using an airopot, and reused coco, this is the second time this has happened not sure if its gh trio part that I'm using? Watering approx 1l q day as the aeropot seems to have dry areas in it one branch always shows sign of thirst before the others.

Any tips greatly appreciated, under a microscope it does appear to be rust rot as doesn't come off...

[davestampy1]

Also my run off was slightly high in the first stage of this symptom but now its similar to what I'm putting in. I'm using coco an the run out is slightly yellow

[azorahai]

I'll start this off by saying I'm hardly an expert, but from the pictures it seems like they might be a bit too close to the light source (light bleaching at the tips, particularly on the newer growth) and with some sort of immobile nutrient deficiency (or pH problem). From the looks of it, I would bet it's a calcium deficiency, as it generally first manifests itself as brown patches on the upper fan leaves. Since you've flushed with calmag, I'd give it a few days before doing anything else. Meanwhile, take some pictures from the top and sides and watch if it gets any worse. The brown patches won't disappear, but they shouldn't grow or spread.

Let us know if it gets any better.

[davestampy1]

Thank you for your input see the top fan leaves yellow at first so thought it was the light. I'm moved the light up a few inches and turned the brightness down slightly. But as all the leaves are pointing up it looks like it wants more lighy

[PLreef]

Looks like nutrient burn on the tips of the leaves.

[Rwise]

At the top of this page there is a link to "Plant Problems" goes here https://www.growweedeasy.com/cannabis-symptoms-pictures
Look up your problem then address the PH.