Diagnosis required

[mrrichiet]

Hi, the attached pics are of a plant about 10 days under 12/12. 3/4 are looking fine but this one seems to be lacking something. It's new growth is yellower than the other plants and the lower fan leaves are deteriorating quicker. The other fan leaves are now notably curled.
From what I read this could be N deficiency, although I have given it some, but I also see it could be a zinc deficiency. However, perhaps as it's flowerings, it's crying out for P & K. Can anyone help pin this down? Thanks in advance.

mrrichiet Reviewed by mrrichiet on 06-17-2004. Diagnosis required Hi, the attached pics are of a plant about 10 days under 12/12. 3/4 are looking fine but this one seems to be lacking something. It's new growth is yellower than the other plants and the lower fan leaves are deteriorating quicker. The other fan leaves are now notably curled. From what I read this could be N deficiency, although I have given it some, but I also see it could be a zinc deficiency. However, perhaps as it's flowerings, it's crying out for P & K. Can anyone help pin this down? Rating: 5

[mrrichiet]

I hope I haven't broken a code of conduct as no-one seems to be replying. I attach a couple more pics if there is anyone out there who could assist. Thanks.

[bonbon]

are you supplementing magnesium?hows the soil PH?whats the grow area tempeture?if you can answer these questions we can narrow it down,find out and let us know,Im sure that someone will have a remedy for you....bonbon
http://oregonstate.edu/dept/hort/dpd/chemkey.htm

[mrrichiet]

Sorry, dumb of me not to put that (it was on another post).

ph c. 6 - 6.5
Humidity 20- 30% (too low)
Temp 25 - 30 oC (too high)
Ferts so far : small amount of ammonium sulphate (N) in veg and small amount of Fishblood/bone (5-5-6.5) during flowering (c.10 days in under 12/12).
Couple of more pics attached. Thanks for the link also.
I still can't decide if it's N an deficiency, or lack of P during flowering. Magnesium and subsequent nutrient lock does sound plausible as I haven't given't it any Mg. In one of the pics, you can see the other plants looking fine (although their lowest fan leaves are starting to droop and yellow).
Anything else I can help with let me know (there may be some more info in my other post on indoor growing msg board "Advice welcomed")

Thanks for taking the interest and your time.

Cheers.

[mrrichiet]

I think I will go with the following excerpt:

1. OLDER LEAVES CHLORTIC, usually necrotic in late stages. CHLOROSIS ALONG LEAF MARGINS EXTENDING BETWEEN VEINS PRODUCES A "Christmas tree" PATTERN. Veins normal green. Leaf margins may curl downward or upward with puckering effect. Necrosis may suddenly occur between veins. POTASSIUM or CALCIUM EXCESS can inhibit uptake of magnesium... MAGNESIUM DEFICIENCY
When the external magnesium supply is deficient, interveinal chlorosis of the older leaves is the first symptom because as the magnesium of the chlorophyll is remobilized, the mesophyll cells next to the vascular bundles retain chlorophyll for longer periods than do the parenchyma cells between them. Leaves lose green color at tips and between veins followed by chlorosis or development of brilliant colors, starting with lower leaves and proceeding upwards. The chlorosis/brilliant colors (unmasking of other leaf pigments due to the lack of chlorophyll) may start at the leaf margins or tips and progress inward interveinally producing a "Christmas" tree pattern. Leaves are abnormally thin, plants are brittle and branches have a tendency to curve upward. Twigs are weak, subject to fungus infection usually leaves drop prematurely; plant may die the following spring.

I guess I give it a good flush and start of again with a weak flowering fert.

Thanks bonbon

[bonbon]

water with epsom salt(1tbs disolved in 1 gal water),i dont think you have to flush since you were giving it a modest amount of fertilizer,the ph is ok at 6-6.5,the mg will bring it up slightly,add a little more phosphorous on the next feeding,the humidity is low because of the hot air,i would just use an outake fan for now and one on the plant,the outake should be able to draw in enough cooler fresh air air,Im sure you're diagnosis is correct also,it will take several days to see an improvement,if the low humidity is still a problem,a shallow container with water in the area should help,good luck to you an post the results....bonbon

[mrrichiet]

Thanks for the advice bonbon. I'll give that a go today and post an update soon.
As you may have worked out by now, I have recently bought a new digital camera, hence all the pics attached! I'm gonna attach the last two now, as I hope they may serve other growers in future. They're of another plant which hasn't got the curled leave problem but the middle fan leaves are starting to discolour. I'll give these the same treatment as the sick one as I'm sure they'll all be lacking the same thing!

[mrrichiet]

I think (and pray) this is doing the trick! I attach a couple more pics - 1 of the baby that was really suffering (seems to be in a better state of health today) and another of one which was showing symptoms on the middle fan leaves (this is getting worse but I hope I've stopped the rot, so to speak).
A question has now occurred to me. Should I remove the damaged fan leaves? I'm guessing I should (cleanly of course) but does it do any harm leaving them there to fall off naturally?
Thanks for a reply.

[mrrichiet]

Sorry, pics attached

[bonbon]

I took a close look at the pic and i thought i saw beads of water caught on some webbing,then a look at the leaves for the little spots,Im sure those are spider mites http://www.cannabisculture.com/backi...ite/index.html