please help me diagnose my problem

[treezzz]

thanks to any one taking the time to read this even if you have no idea what's going on with my plant.

so i have a problem!!! one of my plants is starting to show rust-colored spots around the midrib of the largest leaves! i think i know what the problem is but i want to confirm it with at least one other person before i attempt to correct it so anyone who has an idea feel free to chime in and it will be much appreciated.

here's the stats for my grow so far so you can get a better idea of what's goin on:

its been 2 weeks from when they sprouted
growing using all bagseed
have 14 plants and only 1 seems affected so far
growing in happy frog soil
temp ranges from 70-78 degrees F or so
humidity stays around upper 60's
have not fed any nutes so far
using filtered tap water pH'd around 7.0 (my meter is not great)
no known pests
cfl's and t5 for lighting 24/0 about 200W total

here is a pic to help out hopefully:

any help would be GREATLY appreciated. let me know if any more info is needed.

Thanks!!!!

 

[purzurples]

The pH of your water (and nutrient water when you start feeding) must be between 5.5 to 6.0. I keep mine at 5.8
7.0 is too high.

I dont know what pH probs on a plant look like, but if I saw my plant looking like that I would guess any of these things:
- you foliar fed (sprayed the leaves with water) and your lights burned them a bit.
but those spots dont look like surface damage.
- second guess is the infamous spider mites. if there are tiny tiny strands of silky thread anywhere on your plant, it is spidermites.

Search this site for things related to blasting the sh-t out of spider mites, pick your favorite method, and get to work. Scary? more of a slight time-consuming nuiscance.
Certain plant doom? Certainly NOT. You are the wielder of many mighty chemistries. spider mites are killed all the time.
Start treating soon, monitor how the treatment is working this coming week too.
And this might sound kookie, BUT: it's quite possible the bug got into your grow area by first hopping onto your clothes or hair, and then jumping onto your plant.
You could consider covering your clothes before going near your plant from now on. such as putting on a raincoat before you open the grow room door kind of thing.
I'm subscribing to this thread.

 

[treezzz]

thanks for the advise. i'll look into the pH and spider mite possibilities

 

[Goldengoose7]

The ideal SOIL pH for Cannabis is between 6.2 and 6.8. I wouldn't be surprised if your soil pH is too low (acidic)

I only pH adjust my nutes to 6.5 but I water with 7.0 water and have done for years. Cannabis is much more tolerant of a high soil pH than a low one. Anything in the 5s can cause nute uptake issues called "lockout".

I would suggest buying an IN SOIL pH meter to test your soil pH. Checking the runoff does not always indicate actual soil pH. HydroFarm makes a reasonably accurate meter that sells on amazon for under 10 bucks.

If you are not pH adjusting things like Fox Farm Grow Big back up into the 6s you are probably feeding 4.5 pH water to your plants! That is extremely acidic and will cause the spotting your photos show.

Sent from my iPod touch using Forum Runner

 

[purzurples]

The ideal SOIL pH for Cannabis is between 6.2 and 6.8. I wouldn't be surprised if your soil pH is too low (acidic)

I only pH adjust my nutes to 6.5 but I water with 7.0 water and have done for years. Cannabis is much more tolerant of a high soil pH than a low one. Anything in the 5s can cause nute uptake issues called "lockout".

I would suggest buying an IN SOIL pH meter to test your soil pH. Checking the runoff does not always indicate actual soil pH. HydroFarm makes a reasonably accurate meter that sells on amazon for under 10 bucks.

If you are not pH adjusting things like Fox Farm Grow Big back up into the 6s you are probably feeding 4.5 pH water to your plants! That is extremely acidic and will cause the spotting your photos show.

Sent from my iPod touch using Forum Runner

oh shoot.
treez do what goose says.

 

[treezzz]

thanks gold, i appreciate your input. i actually have that exact soil meter that you are talking about, i believe, and it says my soil pH is at 7.0 or just under it(it's kind of hard to read an exact measurement on it). my plain water run off was also coming up at 7.0 with the chemical pH test kit i got today so i don't know if low pH is the issue, although i don't know if either of these pH testers are completely accurate. do you think high pH could be causing some nute lock-out? i'm really unsure because i've looked all over 420's forums and other sources on the internet and i haven't seen anything that looks exactly like this, although maybe it is because they're seedlings and most pix are of more mature plants. the closest thing i've seen is a calcium deficiency. i couldn't do nothing for much longer without giving up hope for this plant so i gave it a foliar feeding of cal/mag w/ iron twice today at 5mL/gal. i also tested out my earth juice nute tea that's been brewing on 3 of my 15 plants today, including the one with the spots. this tea has grow, cat. and micro. in it so hopefully if the cal/mag didn't help, the microblast will help any defficiencies. after i fed the 3 plants i tested the run off and it was at 6.0 and i used my soil pH tester which said 6.0 also so i guess we'll see what happens

 

[Goldengoose7]

No problem... If you soil is reading a pH of 7.0 then that isn't the source of your problem. As I said, Cannabis can do quite well in a soil pH of 7.0 and there is a very good chance that it could actually be in the high 6 range cause the Hydrofarm meter can be off by a few points.

I would go ahead and continue treating it for a cal/mag deficiency and see how it responds. Go easy though cause a plant that young should generally be getting only water until it is 3 weeks old or so. Young root systems can be easily burned by too much nutes, so proceed with caution!

When I grow from seed, I don't start introducing nutes until the first transplant where I introduce it to Liquinox START with B1 and then, after that I only use Organic Kelp Extract once every 10 days until the plant is approaching 5 weeks of age.

 

[treezzz]

No problem... If you soil is reading a pH of 7.0 then that isn't the source of your problem. As I said, Cannabis can do quite well in a soil pH of 7.0 and there is a very good chance that it could actually be in the high 6 range cause the Hydrofarm meter can be off by a few points.

I would go ahead and continue treating it for a cal/mag deficiency and see how it responds. Go easy though cause a plant that young should generally be getting only water until it is 3 weeks old or so. Young root systems can be easily burned by too much nutes, so proceed with caution!

When I grow from seed, I don't start introducing nutes until the first transplant where I introduce it to Liquinox START with B1 and then, after that I only use Organic Kelp Extract once every 10 days until the plant is approaching 5 weeks of age.

thanks again goldengoose. i treated it with cal/mag and it hasn't worsened at all so far. i gave my other plants a little also to help prevent others from getting it hopefully. i appreciate the advice.

 

[miwa]

wht up treezz...stop using that tap water...u got a ph problem for sure...next tjme it rain...set some buckets out...rain water is the best...it even has micro-nutes in it forget that leaf...watch your new growth...peace

 

[Goldengoose7]

thanks again goldengoose. i treated it with cal/mag and it hasn't worsened at all so far. i gave my other plants a little also to help prevent others from getting it hopefully. i appreciate the advice.

No problem Treezzz! Happy to help!

As with growing anything in pots and doing it successfully, I always recommend sticking to the old "KISS" approach. "Keep It Simple Stupid"

The other old saying that means the same thing.... "Less is More"

This site is loaded with plant issue reports. The majority of which are caused by overzealous growers so eager for a good crop that they fertilize and water their plants TO DEATH!

Using Rain Water Instead of Tap or Bottled Water...

I would be careful using rain water, cause depending on where you live, it can contain pollutants that can cause problems. Rain water can also have a relatively high pH if it happens to contain some of these pollutants that are acid based. I'm sure you have heard of "Acid Rain" ? Well...anyone living within ear shot of a major city is likely to have acidic rain water. At least for the first few storms. And if you do use rain water, you want to do what MIWA suggested and place a bucket out in the open away from any sources of runoff from above such as a roof or tall trees. Collecting rain water runoff from a roof for example will also contain everything that has been accumulating on that roof since the last rain, and the roofing material itself can contain substances you don't want to be feeding to your plants.

Lastly to MIWA... Watering with a 7.0 pH water source that is clean won't hurt your plants because Cannabis thrives in a soil pH of 6.8. Two tenths of a point above that won't make any difference, and the soil tends to lower the pH of anything you put into it anyway. I've been doing what I have suggested here for going on 30 years and I always find that rather than trying to convince other growers as to the virtues of my simple approach to growing in pots, I prefer to let my plants speak for themselves.

 

[miwa]

good info GG...better take my rain barrel from under house drain rudders...didn't think about roof contam...good post...thanks

 

[treezzz]

thank both of you foor your input in this thread. its been 2 or 3 days since i noticed this problem and it hasn't gotten any worse or showed up in any other plants since then. thanks again to both of you