Light Burn?

[stretchpuppy]

I've searched and looked at multiple sick plant threads but I don't know if I see something that looks like this.

This happened on 2 out of 7 of my plants two days ago. The only thing I've done to the setup was a 50% lucas mix 2 days prior to this burn and lower the light a little because the temps were nice and low. I don't think that the nutes are the problem.

Is this light burn? They were even worse this morning. Crinkly and feel like paper. It's weird because it's not the whole plant, just the middle set of branches. It's not getting any worse except for the leaves already effected.


Any ideas?

 

[toofat]

How close do you have the lights? Place your hand over the plant for a few seconds, if it is too hot for your hand then it is too hot for your plants.

 

[stretchpuppy]

You know I did use that method. The light was at about 12" and temps were low 70s, so I thought I could drop it down. Dropped it maybe 3" - the next morning they were burnt. I have an air cooled light and can get my hand within a few inches before I really start to feel the heat. This happened at about 17 days old, PH at 6.5

 

[Verite]

Looks like radiant heat burn from the lights to me. I get the same thing when they get too close. A spot here or there in weird enough places to rule out a feeding problem.

 

[Guest]

Yeah nute burn usually starts on the tips and edges and there would be a bit more yellowing to go with the crispness. What wattage is the lamp? How much air does your fan move? I've heard of peeps saying they could kiss their 1000s glass (I don't suggest trying this) when exhausted properly.

 

[GreatLakes THC]

Check your pH...

Check your pH...

Sounds like you have a heat burn, but I'd also look at your pH. 6.5 is high for most hydro setups. That may be the cause for the leaf curl on a few of your other leaves in the 2nd picture.

GreatLakes THC

 

[Guest]

yea i think it was heat burn also but keep this in mind also it happend to me when you water make sure not to get it on the plant i can bun the leaves the water acts like a magnifying glass when the light hits it and evan thoe you light is no way to close it still can burn well just an idea good luck

 

[guineapig]

man i hate light burn....weedwrapperman is right on about nute burn starting at the edges and working inward.....if you see tiny burnt out spots like these in the center of leaves it is most likely due to a hot-spot.....especially if you noticed them after lowering your light.....i have seen this happen even when plants were placed below a light-mover.....could've swore it was nute burn but it was light burn....who would've thought plants can still get burned even when placed below a light mover?

-kind regards, GP

 

[stretchpuppy]

Thanks for the replys gentlemen. I think you all are right. The plants are still growing except for those set of leaves that were burned. I guess even though the temps were very cool, the plants were still too young for that powerful light. Btw it's a 400w halide.

I'll check PH tonight and see about lowering it a tad.

 

[stretchpuppy]

Is it safe to snip these leaves off? They don't look like they are doing the plant any good at this point.

 

[Guest]

i would but thats me, some folks say not to prune you plant as the fan leaves are used to store nutritives that the plant will need while in flower but i 'd say it's safe .i did mine and they are just fine as the plant grows .i do trim some of the leaves so that light will get threw to some of the lower flowers

 

[Guest]

What you have is not light-burn or heat-stress persay, but you have what is called Chlorosis, and is a condition in which plant foliage produces insufficient chlorophyll. When this happens, leaves do not have their normal green color; they may be pale green, yellow, or yellow-white. The affected plant has little or no ability to manufacture carbohydrates and may die unless the cause of its chlorophyll insufficiency is treated. Certain nutrient deficiencies (often aggravated by high pH) produce chlorosis, which may be corrected by supplemental feedings of iron, magnesium or nitrogen compounds in various combinations.

So, it could be heat-stress which zaps & burns the chloroplasts, or you could have a nutrient defiency of Magnesium, Calcium, or Iron, which all must be present for Chlorophyll to do its work. So, make sure you have the correct pH, correct micronutes (Iron, Mag, Calcium), and make sure the leaves aren't being heat-stressed or too close to the light.

Chlorosis can be from other factors as well, but those are the main ones.

 

[Guest]

wow now that was a lot of info thanks for stoping in !!!!!! well put and very easy to read and understand so how do you test ph in the water do you use the strips and do you do the in water and out water style of testing well once again thanks and as allways

see yea soon

 

[bad wizard]

yea disipline is on to something my lower leaves last go around in hydro was lke that the lower big leaves were lookin like yours.. with some bronzing and the leaf would get sick and die then go up to the next. what was going on was that my ph was 6.5 or so and my resivoir wasn't big enough to go 2 weeks between changes the high ph was loking up the nutes and the plant wasn't getting enough trace minerals. problem solved when i lowered down to 6.0- 6.2 ph and changed resivoier evey 10 days. if i got lazy it came back .. i had 10 diffrent plants 10 diffrent strains it only affected 3 that were sensitive this way. if you have no bronzing i would say you had nute rich drops of water on those leaves coupled with brighter hotter lights voila magnifying glass effect.

 

[stretchpuppy]

Thanks guys. I've done a flush and PH'd down this time to right under 6. We'll see how the plants respond...

 

[Guest]

hey stretch check this out it helped me cools pics to look at and easy to read hope that you find it as helpfull as i did

http://overgrow.com/growfaq/t179
as allways
see yea soon

 

[BullsNBowls]

If the leaves were crispy and dried than it was also a matter of burned leaves too. Just not exposed long enough to fry the leaves. Generally the bigger leaves will get burned first because they store excess H2O and nutrients. Hence the crispy leaves.

 

[stretchpuppy]

Thanks dez, I bookmarked the page.

After the flush and PH lowering the plants are responding well and looking good. The leaves that were already damaged have stayed that way so I trimmed them up.