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Seedling developed brown patches in middle of first leaves


wijn
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Hi all

 

Noticed a worrying development on my baby yesterday evening - brown patches in the middle of the first leaves. This looks slightly worse this morning, and one of these leaves is also now turned up a bit.

 

Herewith, as much detail and history as I can think of...

Strain: Auto white widow

Grow medium: 80/20 coco/perlite. Coco was buffered with Cal-Mag.

Feed/watering: Drain-to-waste, using 2ml part A + 2ml part B Hortimix nutrients per litre of rainwater. Final pH ~ 5.5. Since yesterday evening, I am now also adding cal-mag to the mix.

Environment: Indoor, under CFL for now.

Age: 12 days (since popping out of jiffy pellet)

Other: Gave the coco a neem drench 1 week ago, after seeing what I suspected was a fungus gnat hopping through the coco. About 24h before the problem materialised, I had fan on the plant for much longer than I meant to - about 3h. Also, after seeing the spots yesterday, I panicked a bit and immediately gave the plant a light misting of biogrow pyrol, in case the cause was microscopic insects. I think that this application accounts for the slight shiny appearance on some of the leaves, in the photos.

From images of other unhappy plants I've checked out so far, it looks like the most likely suspects are either calcium deficiency, or rust fungus. Can anyone provide a more definitive diagnosis, based on the attached images?

 

 

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Edited by wijn
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Thanks SkunkPharm - do you think my pH 5.5 feed water is too low? I am using a simple liquid reagent colour test kit, which gives resolution only to 0.5 pH points, so I suppose it's possible that it could be a bit lower than 5.5.

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19 minutes ago, SkunkPharm said:

I think it is safe to make your pH 5.7-5.9. what nutrients are you using?

Sent from my VTR-L09 using Tapatalk
 

Correct, 5.8 is golden with a swing in either direction between feeds. I've found that worked best with coco/perlite.

I'd flush @5.8 and give it a day or two out of direct sunlight, see what happens. When you do feed again, use a little less than seedling dosage. Less is more. :-peace

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Thanks Justin. I think that the damp look may have been from the Bio pyrol. Not certain though. The plant is indoors, in a room with reasonable air-flow. I have a 45W CFL bulb about 8-10cm above it. I don't think that it's getting too hot, but does that sound a bit close? Also, I forgot to mention in my original description that the plant is positioned beneath a window and gets about 2h of mid-morning light per day, in addition to the CFL.

 

As per advice CG420za and SkunkPharm, I flushed with a light nutrient mix on Friday (pH just a little below 6, 1ml part A and 1ml part B Hortimix nutes), then watered/fed yesterday afternoon with the same mix, plus 1g/L cal-mag plus. The damage to the bottom leaves worsened quite quickly on Friday - which I'm sure would have happened regardless of what I'd tried - but I'm a bit worried that it may now be spreading to the next set up. I've attached some updated photos.

 

My plan was to move the plant outside at 14 days - which would be today. Does that sound like a terrible idea at this point?

IMG_20181125_110735.thumb.jpg.8bb46e4b88befa6af5d60bbde05ce635.jpg

IMG_20181125_110809.thumb.jpg.5abe2937427d2fab0ec8be38b3a12045.jpg

IMG_20181125_110859.thumb.jpg.728be9e0aad6c3d850bab4fce91624fe.jpg

 

Edited by wijn
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