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leaves folding upward


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#1
hardball420

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I had a slight salt buildup on a few plants a week or so ago. they're alot better, but the leaves are cupping. You know, kinda folding up and reaching up. They under 1000 HPS
Someone hopefully can answer me this time. Thanks

#2
kooca1z

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Add gardenlime,maybe Higher up the light....

#3
hardball420

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Thanks guys. im done with grasscity for sure

#4
Cast

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Garden lime is easy to kill plants with(learned the hard way) What it sounds like is magnesium deficiency. I know you said you had a salt problem but it sounds like praying for magnesium. cant be sure without pics. can you post some?

#5
Mr.GoodStuff

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Curling leaves are a plant response to high temperatures. The plant cannot absorb enough water so it curls the leaves to get less light (and heat) to the sensative leaf tips.

I imagine you either are experiencing high temperatures (something over 80) or you aren't using fans to cool the leaves. I've had temperatures in the 75-78 range cause problems without the use of fans to cool the leaves.

#6
hardball420

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I missed my opportunity for good pics right when the lights come on the past couple of days. I will try and get some in tonight. Your probably right about the mg deficiency. Thank you so much. Thats just what I needed. Almost everything I've read suggests heat stress, which is practically impossible with water-cooled HIDs. Plus, they seem to do it the worst when the lights are off and then open up for the light. My ppm is fairly low, running around 700. I've had successful runs with the Canna Aqua nutes always staying below 850-900 ppm going in. Something strange though, I think- all plants are sweet and sour deisel clones. But one, just one of them was completely unaffected by the toxic salt build-up (no droop, discoloration, etc.), and is six inches shorter and flowering days earlier. Thanks again!

#7
Mr.GoodStuff

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Even if you are using water cooled lights, the leaves can absorb heat and stay hot without being cooled by wind. Ambient temperature is also very important, but with a fan things aren't so bad.

If it is a deficiency it's most likely because of heat stress and not a problem with your nutrient solution... Especially using Canna nutrients.

Can you get ahold of an infrared temperature meter (leaf temp thermometer?) That would definitely help us pinpoint the issue.

Also, what is the ambient temperature in the shade- and how much air movement (wind) are they seeing?

#8
hardball420

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Hey Mr. GoodStuff, first off, thank you for your posts. Yes you are right, with certain deficiencies you can burn leaves with just a little heat. Even with water-cooled lighting. They were hung at about 8 inches which is usually adequate. However, I just raised them to well over a foot after reading these posts.

As for ventilation, I have one large oscillating circular fan that blows across only the top of the canopy, and one small, static circular fan that sits on the table and stirs the air beneath. I also have a mobile a/c blowing upward above the lights, which runs constantly. It is a duel exhaust which I have left the intake open in the room to exhaust air out until the completion of the installation of my water-cooled co2 gen. I also just installed a can fan in the attic which I planned to air-cool the light tubes with to get my energy consumption down. I may just use it as an exhaust fan and use my a/c properly. With all this Im still fighting with powdery mildew. It was a cheap oscillating fan and doesn't blow super hard.

I have two thermostats in the room- one digital placed just below canopy level, and one on the wall a couple few feet away. They both read between 75 and 80 F usually. But on hot days it can be as high as 87 88 F.

With the ppm around 700 one and a half weeks into flowering do you think maybe that is low? I have'nt read anywhere they do this from overfertilization. One plant has the tips slightly burning like it is either a K deficiency or nute burn which sounds unlikely

Anything helps guys THANKS

#9
hardball420

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Trouble uploading other pics

Attached Thumbnails

  • PIC-0160.jpg


#10
hardball420

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Another day, and that one plant I mentioned is still the only one flowering.

#11
Mr.GoodStuff

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I don't have any experience with canna nutrient except for Cannazym, Cannaboost, and Rhisotonic... But it seems low really. Under a lot of HID light, especially using a 1000 watt light at a foot or so- you need to feed them at least 1000 ppm on a .5 meter in every single nutrient formula I've ever used.

At 8 inches, the amount of lumens those plants were getting were actually overboard if you want to maximize yield. A 1000 watt light will lose footprint the closer you hang it and the large footprint at a high hanging point is it's strong point. The leaves will block the light from getting further down the plant and the light is actually wasted that way. By hanging the light higher, at 2 feet, you can get a great 4X4 footprint of light to work with.

You can use a lumen meter to see just how much light you can work with with the light hung higher. Sometimes closer is not better, especially with a 1000 watt light. It's because of the leaves blocking light to the lower parts of the plant.

Also if you are fighting powdery mildew- you should look into spraying them with an organic tea made with compost dominated by beneficial fungus and bacteria. A beneficial fungus type called trichodermia will actually even eat it and then guard it! There are lots of products with it, like Advanced Nutrients Piranha, or that Organism from Roots organics. But with a good organic tea it should dominate the leaves and cause the mildew not not have any room to grow. It's like a parking lot not having any more parking spots.

Plus, the beneficial microbes produce powerful growth and bloom enhancing hormones. So yet another reason to try it. lol

You might want to look into a HEPA filter as well. Make sure you don't see that demon mold again!

Edited by Mr.GoodStuff, 03 July 2009 - 05:05 AM.


#12
hardball420

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Hey thanks that gives me an idea. This is a different strain than before but it definitely seems they want more nutes.

I was told water cooled lights filter about 6 to 10 percent of the over lumen output, and that a few inches would compensate. I need a light meter, I suppose.

Thanks for the info on the foliar spray for PM. It showed up late last harvest with little consequence, but is still around. Definitely, will pick some up.


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