PLEASE HELP! Brown/ rust spots on fan leaves with purple stems (Week 3 flower)

Hey guys,

Currently got three Crystal Candy XL autoflowers from sweet seeds on day 20 of flower. 2' x 2' grow tent (73-78F & 45-55% RH) with 110W LED grow light at 35cm from plants. Grow medium is Bio Bizz All Mix feeding Bio Grow 1 ml/L, Bio Bloom 2 ml/L, Top Max at 2 ml/L, AlgAMic 1 ml/L + Tap water at 6.3 PH.

Everything perfectly healthy and leaves praying however around 5 days ago I noticed brown/ rust spots and purple stems appearing on fan leaves throughout the cannopy of one of my plants which has since spread. This is now begining to affect a second plant leaving the third unaffected. From what I have found online it looks like a calcium deficiency or a nutrient lockout. I tested run off with 6.5 PH plain tap water and it came in at 5.8 PH and 1400ppm for both plants.

What is this?

I don’t know what it might be but my girl started the same thing just a couple weeks into flower. I thought calcium deficiency. Tried adding cal mag. It has only gotten worse. Now 5 weeks in.

My crystal candy fast version got those same spots, I think it was a PH lockout because I didn’t calibrate my PH pen, and watered with LOW ph’d water once. I calibrated the pen and watered with correctly PHd water after that. It seemed to do better every time I added a layer of new soil(FOX Farms Ocean Forest) so maybe it was just hungry. It never really went away but the plant flowered and finished just fine anyways

TessaMaria said:

My crystal candy fast version got those same spots, I think it was a PH lockout because I didn’t calibrate my PH pen, and watered with LOW ph’d water once. I calibrated the pen and watered with correctly PHd water after that. It seemed to do better every time I added a layer of new soil(FOX Farms Ocean Forest) so maybe it was just hungry. It never really went away but the plant flowered and finished just fine anyways

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It’s pH.

I appreciate the replys guys but I haven’t really gotten anyhwere with this info. If it is a PH issue, how can I fix this in organic soil? Why would it be PH related when I test my feed at 6.3 PH every time?

Kriptior said:

I appreciate the replys guys but I haven’t really gotten anyhwere with this info. If it is a PH issue, how can I fix this in organic soil? Why would it be PH related when I test my feed at 6.3 PH every time?

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I’m guessing you have root problems.

hotrodharley said:

I’m guessing you have root problems.

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Due to? How do I fix?

Spotting is now affecting sugar leaves. Getting worse quick so would really appreciate some guidance on how to try and fix this!

Kriptior said:

Due to? How do I fix?

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Did you inspect with 25x loupe or greater for bugs?

One way to figure out roots is pluck the plant and look. Nobody would do this with a healthy flowering plant but since your plant looks like it might be in a downward spiral it wouldn't hurt. It's an emergency.

Can you gently mush the sides of the pot and pluck the pant so that all the soil maintains shape? If yes, pluck and post pics.

Is 1400ppm high for week three?

"rust spots and purple stems appearing on fan leaves"

I googled that and more than one source indicated purple stems/"phosphorous deficiency".

Is it possible you are over fertilizing which is creating an unintended lock-out?

Kriptior said:

I appreciate the replys guys but I haven’t really gotten anyhwere with this info. If it is a PH issue, how can I fix this in organic soil? Why would it be PH related when I test my feed at 6.3 PH every time?

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If you're using pH down, stop and see what happens.

rmax said:

Did you inspect with 25x loupe or greater for bugs?

One way to figure out roots is pluck the plant and look. Nobody would do this with a healthy flowering plant but since your plant looks like it might be in a downward spiral it wouldn't hurt. It's an emergency.

Can you gently mush the sides of the pot and pluck the pant so that all the soil maintains shape? If yes, pluck and post pics.

Is 1400ppm high for week three?

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I don't have a loupe however I have checked for bugs and found nothing.

I don't really feel comfortable removing the plant from the pot just yet. I'll do this as last resort if I can't find what is wrong soon.

I have the same question, is 1400ppm high?

rmax said:

"rust spots and purple stems appearing on fan leaves"

I googled that and more than one source indicated purple stems/"phosphorous deficiency".

Is it possible you are over fertilizing which is creating an unattended lock-out?

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I upped Bio Bloom and Top Max from 1 ml/L to 2ml/L around 1.5-2 weeks ago. Should I cut back down to 1ml/L?

PadawanWarrior said:

If you're using pH down, stop and see what happens.

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I have been using vinegar to lower PH. My tap water is 7.8 PH, would it be safe watering unaltered?

Kriptior said:

I have been using vinegar to lower PH. My tap water is 7.8 PH, would it be safe watering unaltered?

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Ya, the soil should buffer it. My water is around 7.8 too and I just do plain water. My soil pH is in the low 6's.

Kriptior said:

I have the same question, is 1400ppm high?

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I use EC VS PPM.

According to this conversion chart I found on the line, IMHO, yes 1400 PPM is too high for week three flowering. That's EC 2.0! I don't have the expertise to advise what your EC/PPM should be. I try to stay 1.5 or below.

Let's ask the other successful growers where their EC/PPM range.

lockout caused by low ph. your soil is too acidic. also 1400 is 300 higher than i ever go, but that's beside the point. if you really want to take some kind of action, flush your plant with 3x the capacity of your pot with ph 6.8 water. let all that water drain out, and then do a regular watering with nutrients at half strength. check the ph of the runoff from the final watering with the nutrients. between 6 - 7 and you're good.

aw_cmon_baby said:

lockout caused by low ph. your soil is too acidic. also 1400 is 300 higher than i ever go, but that's beside the point. if you really want to take some kind of action, flush your plant with 3x the capacity of your pot with ph 6.8 water. let all that water drain out, and then do a regular watering with nutrients at half strength. check the ph of the runoff from the final watering with the nutrients. between 6 - 7 and you're good.

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I am in organic soil, is flushing a good idea?

Kriptior said:

Spotting is now affecting sugar leaves. Getting worse quick so would really appreciate some guidance on how to try and fix this!

View attachment 4862004

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This is starting to look fungal. If you rub it between thumb and finger does anything come off?

And if it’s near other plants consider isolating it.