HELP! Rusty brown spots on leaves (pics) +rep

guy incognito

Well-Known Member
I have 4 plants all started at the same time, 2 different strains, but all plants are showing the same symptoms which is brown spots appearing on the leaves, and some other "burnt" areas on leaves.

planted from clone in 6" pot with miracle grow moisture control and perlite (2:1) 9-21-10
fed tap water and used cfls for vegging on a 18/6 cycle

on 10-21-10 I transplanted it to 3 gallon pot and used 2 different mixes. One was fox farms happy frog soil with perlite (2:1), and the other was miracle grow moisture control with perlite (2:1), 2 plants for each mixture.

flowered under 400 watt hps, about 12" away. day time temps are getting up to about 80. I havent seen the temp drop much below 65F. watered with store bought reverse osmosis water (RO). I started the first week or so with straight RO. Then I fed a single time with about 3/4 dosage of botanicare pro bloom (1-3-4). I purchase cal-mag plus about a week ago and have been using 5 ml per gallon of RO for all waterings since.

The pH of my RO is 5.9. pH with cal-mag and nutes in any combination is 5.9 also. I have not tested the ph of the soil of the plants as im unsure how to precisely do this.

How would I go about checking the ph of my soil? or should I test the run off?

My last crop did this same thing, but much more severe.

It's happening on every plant. The pictures aren't coming out the clearest, but the rust spots are on many leaves.

Edit: this 1st picture is NOT the rusty brown spots im referring to. This only happens on a few leaves.


Edit: these 2 have rusty brown spots:


 
You should probably bring the ph up to around 6.5. and it looks like it might be a little bit of heat damage. Resembles some heat stress my plants suffered from a few weeks ago. maybe cal/mag though?
 

guy incognito

Well-Known Member
You should probably bring the ph up to around 6.5. and it looks like it might be a little bit of heat damage. Resembles some heat stress my plants suffered from a few weeks ago. maybe cal/mag though?
My hps has been on for 9 hours along with my furnace and it's only 78*F in there now. I got a cool tube running. I am pretty certain it is not heat damage.

How should I bring my pH up?
 
They sell ph kits at most hydro and gardening store. you just add some up solution according to the bottle. should probably help
 

abberation

Active Member
I have 4 plants all started at the same time, 2 different strains, but all plants are showing the same symptoms which is brown spots appearing on the leaves, and some other "burnt" areas on leaves.

planted from clone in 6" pot with miracle grow moisture control and perlite (2:1) 9-21-10
fed tap water and used cfls for vegging on a 18/6 cycle

on 10-21-10 I transplanted it to 3 gallon pot and used 2 different mixes. One was fox farms happy frog soil with perlite (2:1), and the other was miracle grow moisture control with perlite (2:1), 2 plants for each mixture.

flowered under 400 watt hps, about 12" away. day time temps are getting up to about 80. I havent seen the temp drop much below 65F. watered with store bought reverse osmosis water (RO). I started the first week or so with straight RO. Then I fed a single time with about 3/4 dosage of botanicare pro bloom (1-3-4). I purchase cal-mag plus about a week ago and have been using 5 ml per gallon of RO for all waterings since.

The pH of my RO is 5.9. pH with cal-mag and nutes in any combination is 5.9 also. I have not tested the ph of the soil of the plants as im unsure how to precisely do this.

How would I go about checking the ph of my soil? or should I test the run off?

My last crop did this same thing, but much more severe.

It's happening on every plant. The pictures aren't coming out the clearest, but the rust spots are on many leaves.

Edit: this 1st picture is NOT the rusty brown spots im referring to. This only happens on a few leaves.


Edit: these 2 have rusty brown spots:


Your PH is definately to low. Get some PH Up from a store and add to your solution. Testing the run-off wont give you the ph of your soil as you will be testing the run-off and everything else you added to the watering solution. You can get soil ph testers that you stick into the soil. They aren't expensive.

Picture of one

Are those brown spots getting worse after you started giving the cal-mag or better. Also do you know what your RH is? I'm thinking that your problem is more fungal. If it is, you will have to remove the infected leafs, also get some biobizz leafcoat, its a very good product that protects your plants against harmfull fungus and insects.
 

guy incognito

Well-Known Member
Your PH is definately to low. Get some PH Up from a store and add to your solution. Testing the run-off wont give you the ph of your soil as you will be testing the run-off and everything else you added to the watering solution. You can get soil ph testers that you stick into the soil. They aren't expensive.

Picture of one

Are those brown spots getting worse after you started giving the cal-mag or better. Also do you know what your RH is? I'm thinking that your problem is more fungal. If it is, you will have to remove the infected leafs, also get some biobizz leafcoat, its a very good product that protects your plants against harmfull fungus and insects.
The cal-mag seems to have no effect. Everyone told me mg deficiency, but now that i'm using RO and adding cal-mag I still see it.

RH is staying around 30-50% during the times I check it. No idea what it is during dark cycle.

Would it be fungus on the leaves, or in the soil? I have an oscillating fan blowing on them.
 

guy incognito

Well-Known Member
Low pH could cause a lockout of phosphorus correct?

Phosphorus was abundant in the previous crop but I had the same problem. So if it's a phosphorus deficiency I would suspect it's actually a pH issue.
 

guy incognito

Well-Known Member
Maybe I was super high (I was) when I did my pH testing after I got my meter. I retested things last night:

RO = 5.9
RO with cal mag = 5.9
RO with cal mag and botanicare nutes = 3!!!

I have laboratory grade KOH and I was adding it to the solution but I can't bring it up. I put several grams of pure KOH into the solution and it quickly went up to a pH of 5 and STAYED THERE. It did not move no matter how much KOH I kept adding. The water is cloudy and funky looking now, and the nutes keep separating from the water (bottom 1/3 is brown, top 2/3 is cloudy - does not do this with no KOH).

What should I use to bring the ph of my watering solution up?
 
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