Diagnose This

seysonn(8a WA/HZ 1)February 19, 2014

I have a dozen or so pepper seedlings growing under fluorescent tubular (T8) light. One of them, AS SEEN IN THE PICTURE, has developed brown-purple leaves. It is a Thai Chili. There is another one (Hungarian HW) which has slight discoloration on one or two leaves:

Can you PLEASE tell me what the cause is ?
All my seedlings are under the same light, the same place and watered/fertilized the same way.

Thanks in advances.

This post was edited by seysonn on Wed, Feb 19, 14 at 3:38

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mswiggi(5)

Phosphorus deficiency? What is the temperature in the room?

    Bookmark   February 19, 2014 at 5:49AM
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habjolokia

How long are your light cycles? Have you forgot to turn them off at any time and had 24+ hours of light exposure?

Mark

    Bookmark   February 19, 2014 at 7:47AM
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seysonn(8a WA/HZ 1)

@ misswiggi ... I have read on the net also "P" deficiency can be one POSSIBLE reason. But this is one out of 15 !!!

Mark, I have never left the light on for 24 hrs. I used to have it on for 16 hrs. Lately I am going by 12/12 approx. ( No timer). Room temperature had been 60 -70F. Cooler at night.

Again, considering that this is almost the only one with this feature. I suspect that at one time the light might have been too close, MAYBE ! Also, maybe a few nights the temps had been under 60F.

I am using very dilute solution of MG all purpose ( 12 -4- 8)

Thanks guys .

    Bookmark   February 19, 2014 at 9:25AM
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esox07

I might be thinking "cross" if the leaves are darkening up that much. Pepper varieties that normally grow darker foliage will grow green to begin with and as the leaves age, they will start to darken. Meaning the lower leaves will darken first. That kind of looks like what is happening in that picture. The newer growth is nice and green but the older growth is darkening first. I learned that this year from Josh (Greenman28) from growing a Black Pearl.
Here is my black pearl on February 11th and then again on February 15th, just 4 days later. You will notice that even now, the newest growth is still green. The Black Pearl in the photo is not a cross, but I think that your pepper might be a cross with a plant that normally exhibits dark foliage like the black pearl.
So, my guess is that you have some kind of cross there.
Bruce

    Bookmark   February 19, 2014 at 10:53AM
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abnorm(Orlando)

That has the blochy look of "sunburn" I get on mine from TOO much light.......

    Bookmark   February 19, 2014 at 1:05PM
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greenman28 NorCal 7b/8a

Any chance you could take a clear image?
Hard to tell anything from that pic.

Josh

    Bookmark   February 19, 2014 at 1:19PM
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thepodpiper

It could be a normal reaction to excessive lighting (defense mechanism in the plant) although I have never seen it to that extreme. I wouldn't jump to conclusions on a deficiency just yet, the plants look healthy. My opinion would be 2 let them go for now.

In my experience sunburned leaves are white almost translucent.

Nice looking plant esox07.

    Bookmark   February 19, 2014 at 1:27PM
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kuvaszlvr

That's weird Bruce. You're really starts out green? My black pearl leaves start black and stay black. Are there different variants out there? That's weird.
Pam

    Bookmark   February 19, 2014 at 1:32PM
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greenman28 NorCal 7b/8a

In Bruce's case, that first test Black Pearl was started on a window-sill...correct me if I'm wrong, Bruce. Bruce's subsequent Black Pearls were started under lights, and they came out with the purple-black cotyledons that we all anticipate. Now that Bruce's test Pearl is maturing and under lights, the leaves are darkening up dramatically.

Josh

    Bookmark   February 19, 2014 at 1:42PM
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esox07

Josh is correct, right after that first picture, I put it under my floro shop light with my seedlings. It had been growing in a window sill up until then. Within a few days of getting the floro light, it blackened up very fast. I have some more seedlings coming up now that are a couple weeks old. They are just starting to get their first set of true leaves and those are coming in quite green while the cotyledon leaves are very black. Here is a photo of them from two nights ago. Notice the Black Pearls are labeled and one of them even has quite green cotyledons.
Bruce

    Bookmark   February 19, 2014 at 1:56PM
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seysonn(8a WA/HZ 1)

Thanks everybody for your input.
Bruce, I don't think you theory is applicable here. I only suspect lighting.

Josh, the picture that I have posted is pretty realistic.
Here is a picture with similar problem from the net:
In my case the discoloration is much more pronounced and deeper.

This post was edited by seysonn on Wed, Feb 19, 14 at 14:27

    Bookmark   February 19, 2014 at 2:25PM
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woohooman

That happened to me before. I can't recall what mix I was using, but I do recall that they grew out of it.

What's the mix made of?

Kevin

    Bookmark   February 19, 2014 at 2:57PM
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greenman28 NorCal 7b/8a

The quality of your first pic is pretty bad (fuzzy, can't tell if the white is burn or glare), but the pic that you just posted (from the 'net) shows, indeed, some over exposure. Can you raise your lights? I think your plant should recover just fine.

Josh

    Bookmark   February 19, 2014 at 3:03PM
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esox07

Seysonn: Yes, I believe you are right. I was referring to my plants and kind of hijacked your thread in the process. I apologize about that. In that last photo that you posted, the plants look awful yellowish. Are yours that way as well?

I have never had a problem with too much artificial lighting. I also use T8 floro shop lights. If it was me, I would probably limit the water and stop the nutrients altogether. I don't really think it is a light issue but just for reference, what light spectrum are your bulbs rated at? If they are not at least 4000K, you might want to think about getting something closer to the "Daylight" rated bulbs in the 5000-6500K spectrum. Regardless, those plants look pretty healthy otherwise.
Bruce

    Bookmark   February 19, 2014 at 3:44PM
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seysonn(8a WA/HZ 1)

Josh, Thanks. My picture is not as perfect but it depicts the discoloration. I think you are most probably right: OVER EXPOSURE is probably the cause. I have read many post (here and elsewhere) that the light source can/may be almost touching the seedling. My light source has never been placed that close but at times might have been about 1/2" or so. Now I will keep it a little farther from now on. And I am also going to do it 12/12 on/off.

Bruce, I am watering them (from bottom) once a week and have been using weak 12-4-8. I will cut down on those per your advice. Thanks to you all.

BTW: My medium is a sort of home brew:
-- some store bought seed starting mix
-- some screened pine bark fine
-- some vermiculite
-- a bit of perlite
-- some MG potting mix(very little). This stuff has some nutrient in it.
I have also sprinkled some Epsom salt and calcium( like salt an pepper shake)

    Bookmark   February 20, 2014 at 1:56AM
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woohooman

I'd ditch the epsom and Ca for now. More important when flower formation occurs.

I fertilize maybe once/twice in the seedling stage before transplant.

Kevin

    Bookmark   February 20, 2014 at 11:57AM
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greenman28 NorCal 7b/8a

Interesting.
Bottom-watering tends to concentrate salts in the soil.
How about doing a flush from the top for your plants? I don't think it'll hurt, but could potentially help.

Josh

    Bookmark   February 20, 2014 at 12:39PM
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esox07

OHHhh, that's it. Josh, I remembered you had recommended to top water more often and for the life of me, I couldn't remember why you recommended that. I will have to remember to do that more often this year.
Bruce

    Bookmark   February 20, 2014 at 1:02PM
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seysonn(8a WA/HZ 1)

OK. good catch, Josh
That is right about "bottom watering", ACCUMULATION. Primarily i used bottom watering to prevent pests, mold, etc.indoors.

The next time , I will do a flush watering. That should do it.
And will stop fertilizing for a while, too.

seysonn

    Bookmark   February 20, 2014 at 8:47PM
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