Light Stress?

[anarchitect]

Greetings. I'm wondering whether-or-not I've nute burned or light burned my plant. It's had parts of it's fan leaves (all over the plant-not just the top) turn yellow and dry away. There's no real pattern to this yellowing. Some have yellow spots in the middle of the leaf, some have the entire leaf dying and drying up. And the new leaves coming from the bud tops are emerging w/a "different" look to 'em. They are smooth rather than serrated, and forming in a crooked, kind of twisted manner. (sorry no pics yet)

I gave her a fairly strong dose of Pure Blend Pro Bloom (45ml/1gal) and left her alone for a couple of days. It's after that feeding that I noticed the yellowing. Thing is, I had just moved her indoors and placed her approximately 12-14 inches under a 400w HPS that's got two 150w HPS mounted off to the sides of the reflector (700w total). Temps range from 61 deg F to 94 deg F averaging around 84. So I don't know if it's light stress or nute burn. From what I understand, it's pretty hard to burn with the Pure Blend line. 'Nother thing, the Pure Blend is for Hydro, and this one's in soil. Would that make a difference?

Thanks in advance for all the first-hand knowlege. Peace.

 

[Cheeba]

Maybe you can tell us what it looks simliar to if you don't have a pic. Here's The Complete guide to sick plants - Mynamestitch

 

[Purpleseed]

Have you checked your ph?
If you have a fan blowing on top of plants the distance of the light sounds ok.
I don't see how the light would burn the bottom leafs.
Twisties from new growth sounds like stress.

 

[Guest]

I think I'm having the same problem ... I just took half my plants from veg to 12/12 (400w MH changed to 400w HPS) three days ago. I gave them a shot of 'transistion' nutes : GH grow/micro/bloom 5-5-5ml/gal. Now, all new growth is yellow. Plants are tied LST, and all shoots are yellow, although the main growth tip is almost green. I also gave the plants a foliar feed of Cytokinin (kinetin). The other plants still vegging are nice and green. The only difference between flowering and vegging besides lights is temps. Vegging area stays 76-80, while flowering area goes 62 - 85. I modified my cooling system this A.M. to get flower temps 76-80. Does anybody have any ideas ? I'm worried as I am leaving the country for 8 days, and my wife will be taking care of them for me. Here are some pics, it's harder to see the difference with the HPS. Captu4ik.

 

[anarchitect]

I'm sure it's light stress / heat related in my case. I took pics this weekend, but I don't have 'em with me.

She's also gone hermie on me. Seems I was a little over enthusiastic in testing the limits of my new 400w HPS, and abused her too much. She (it's) got male flowers popping up all over the main cola (to the point I just chopped the whole thing off) and on a couple of the secondary colas. I'm trying to just pick those off as they appear. Seems like they appear awful frequently though.

I think that having the air conditioning blow directly onto the plant also contributed to the stress factor. Looks like the leaves were "wind burnt" - they dried out faster than the rest of the plant, and took on a "sick" appearance. I've moved that duct to blow onto the container they're in, and that area of the plant is starting to look healthier.

I suppose I'll have to clean my bloom room with bleach after I give this one the chop. Make sure there's no errant pollen laying around. Thanks to everyone for contributing. You just can't beat first hand knowlege. Peace.

 

[anarchitect]

Hey Alex. Something that I believe is a problem with the HPS, is that regardless of the temps, they can sometimes "bleach" the leaves. I'm fairly new at this, but that's something I've seen with my plants. I'll move the light back, and they seem to get greener.

Anybody else experience this?

 

[Guest]

I've totally re-modeled my flowering area now, and though I still don't know the exact cause of my problem, things are green again. Understand, I'm in the tropics, and we just had our first day under 80F since April, but temps were getting down to 60F in my grow area, and this air was being blown right across the plants. Those closest to the air intake seemed to be affected the worst. I've switched to ambient air, and day/night temps are 72 to 78 -- perfect. I did move my HPS about 14" above the plants. Good luck and keep it green -- Alex.