Are these brown spots cal/mag deficiency?

There are 1 or 2 plants showing these brownish spots on a few leaves. Some of the spots have grown into small brown patches.

These plants are 5 weeks old and have been in 12/12 for 1 week. They are watered with tap water treated with vitamin C (for chloramine removal), so I doubt there's an actual calcium/magnesium deficiency in the water. It's possible the pH swung pretty low for a short period (1-2 weeks).

What do you think these spots are caused by? I'm certain they aren't spider mites as I've seen the damage from them and this is different...

Also, do you have to worry about calcium/magnesium deficiencies in tap water if pH is good? If you're running about 150 ppm hardness then you should have enough of BOTH calcium and magnesium, right? Can't you lock out magnesium somehow by having too much calcium or vice versa? Can someone explain this to me?! Also, how can I verify and resolve?

Looks like the light may be too close. I only say this as I noticed the edges of the laef has turned upwards indicating that it could possibly be getting to hot as the leaf is trying to sweat. How close is the light as it could be heat or light or a combination of both ?

Could also be that your nutes may be slightly high ?

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Originally Posted by nexusmick

Looks like the light may be too close. I only say this as I noticed the edges of the laef has turned upwards indicating that it could possibly be getting to hot as the leaf is trying to sweat. How close is the light as it could be heat or light or a combination of both ?

Could also be that your nutes may be slightly high ?

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Thanks for addressing the "canoeing" leaves. I was wondering about that too and I think you may be right about the heat. However, these brown spots are appearing on random leaves and they aren't on the leaves that are closest to the light. So, I don't think these are related to light/heat.

I remember seeing a picture very similar to mine and it seemed like a pretty clear-cut diagnosis. I can't seem to find that thread now though!

I'd noticed this before adding ANY nutes, although these are in Fox Farms Ocean Forest Soil and from my limited experience so far that soil is hot enough to stunt and cause problems with freshly tranplanted clones.

I don't think you have any problem, I see this on young plants.....could be from a light burn.

The canoeing as you call it, should concern you. That plant is stressing, trying to transpire a lot. Might be too wet in the pot.

Is that a clone or seed stock? Looks female to me

:rasta:Good Day
I am looking after 46 plants for a client and I just went through what you are going through now. And yes it looks like the start of a Cal/Mag problem. The curling of the leaves would confirm this. Do you have brown spots that look like rust are on leaves that are on side or bottom of plant with very little chance of light burn!!???? And small holes starting on leaves???

What I did to correct the problem was flush the plant with water. I used 5 gal bucket of water PH 6.3 and poured it into plant pot. The size of the Pot is 1 gal and let it drain out. The next day I mixed ¼ % Fish Emolusion and lightly fed plants. Next water was normal water with Fish Emolusion. Looked after the problem real well in 2 weeks back to normal.

I over fertizized my plants and they all had this problem. I also used Epsom salts at 1 Tablespoon per 1 gal of water and foler sprayed all leaves until gal of water was all gone. I managed to spray 3 times.

Good Luck
Surrey Compassion Club
:hippy:

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Originally Posted by sccrocks

:rasta:Good Day
I am looking after 46 plants for a client and I just went through what you are going through now. And yes it looks like the start of a Cal/Mag problem. The curling of the leaves would confirm this. Do you have brown spots that look like rust are on leaves that are on side or bottom of plant with very little chance of light burn!!???? And small holes starting on leaves???

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I think you're right unfortunately. I see a lot of these brown spots on leaves near the middle of the plant and it's definitely not light burn.

So, you think the leaf edges curling is related to the brown/rust spotting? Is curled leaf edges a sign of Cal/Mag problems too?

Since I'm using tap water, the only thing I can think of is the pH being off. I did get some pH runoff water that was about 5.5 and this was after watering with pH 6.5-6.8 water. So, I think my soil pH was pretty low (<5.5) and I don't know how it got that way as I always pH my water to 6.2 - 7.0 before watering. So, it must be this FFOF soil.

I gotta get this figured out as it doesn't appear to be getting better! The plants were recently transplanted into bigger pots so they are taking forever to dry out now. Should I start a flush even though the plants are still pretty moist from the last watering? Arrrghh... they're gonna take 5-6 days to dry back out after the flush!

I had this problem with my plants a couple of weeks ago. I think the 2 problems are seperate issues. I have posted the solution that worked for me in the your other thread.

This thread can be closed as I believe it's associated with another problem that I'd already posted about. See the thread titled, "I thought this was canoeing leaves".