Brown spots and a crumbling leaf

[menk]

Problem: Brown spots on a few leaves / one leaf is getting crispy and is half gone
Medium/grow method: Soil: 2/3 OF and 1/3 Perlite - 5 gal fabric pot
Feed: and supplements used: Fox Farm- fed 3x with big bloom, once with Grow Big at 1/4 strength.
water source: Tap water (left out for a few days to evaporate the funk) then PH'd to 6.5
Strain/age: ILGM Northern Lights - approx. 40 days
light used: Platinum LED 300W / about 20 inches above
Climate: 70/80 Degrees, 45-60% RH
Additional info: This is my first grow, I've been going light on the feeding after reading that autos don't require the same amount of nutes as a photo plant, also that OF is supposed to be a hot soil.
Originally i thought it might be nute splash on the leaves, but with the one leaf half gone that kind of rules that out. Cal/mag deficiency?

 

[GoAuto6]

Do you have a soil probe, I suggest the accurate 8. Why you ask fox farm soil is notorious for pH not being on par. If you can probe the soil you can adjust your water and feeds to adjust your soil.. in short I think you have a lock out issue.

 

[menk]

No I don't have a soil Probe...I can pick one up no problem. I didn't say that the ph in the soil was off...just that it was loaded with nutes right out of the bag and that adding anymore might cause some burn. I always adjust the water to around 6.5 ,(the tap comes out at about 8.5). I did check the runoff last time i watered and it was 6.7.

 

[GoAuto6]

Run off is a tuff one some where around her I posted an equation on adjusting pH through run off. I'm on a phone and can't seem to find it. Look for jm's thread I think it's call pH adjusted hydrogen? Ffof can be hot especially with auto flowers....

 

[menk]

Ok...thanks for the info, i'll search out that thread. I did run across an old soil test kit i forgot i had, I'll see what kind of readings i get with it.

 

[menk]

Well after checking the soil (chemically) the PH is between 6.0 and 6.5 (its color based) so it seems the PH is ok. (i have a digital ph tester showing up this week so i'll retest it then). But the problem seems to be getting worse, here are more pics. It starts off as small brown specks on the leaves and then grows from there, eventually taking the whole leaf out. you can see it eating holes on a few of the leaves. Anyone have a clue as to whats going on?

 

[Arthur]

Last picture, left hand upper side, what am I seeing that looks like dried droplets on that leaf? Doesn't look like nute burn to me, pests? I used OF &HF for years with photos, ocean forest is to hot for seeds or seedlings I used HF this past spring and it was fine. But recently have seen a lot of issues on their quality control. Am moving away from fox farms at this point.

 

[menk]

@Arthur, yeah there are some dried water spots on some leaves, I spilled some nutes and rinsed them off. I'm starting to wonder if the brown spots are from the water drops on the leaves acting like little magnifying glasses. Maybe they're just burns? I thought about checked for critters also but haven't found any yet. I read a few things about fox farms having issues but i still have a bag of HF so I'll see how it works.

 

[Arthur]

@Arthur, yeah there are some dried water spots on some leaves, I spilled some nutes and rinsed them off. I'm starting to wonder if the brown spots are from the water drops on the leaves acting like little magnifying glasses. Maybe they're just burns? I thought about checked for critters also but haven't found any yet. I read a few things about fox farms having issues but i still have a bag of HF so I'll see how it works.

Have been on a lot of threads as of late... so forgive a forgetful stoner if I forget a post from a previous page!


If you have HF I'd have no worries in using it, just check and adjust the pH prior to planting...I'd even say I'd use the OF before using a miracle grow (monsanto) product....just do some prep work, and understand OF is really for transplanting full size plants... finding out your soil pH is off halfway thru a grow is no fun!
And it is possible for water drops to act as a magnifying glass. One of the reasons I'll foliar feed no later than 30 minutes before lights on.

 

[Waira]

-- weird symptoms menk, I'm not sure what this is....spots and the way they form doesn't fit well with any defc/toxicity; lower leaves edge wasting is a pretty generic symptom, not distinct enough to can with certainty... So, your water is 8.5 pH? That's very high,... do you know if you have very hard water? Unless you happen to have a TDS/EC meter,...And have you calibrated the pH meter recently, and keep it stored in the proper storage solution? I want to make sure the readings are good,... not caring for them properly makes them give unreliable results,....
... that old soil pH test kit, how old and well stored? the reagents used for testing can go bad and give crap results,.... If you want to get a good in-pot pH reading (run-off method is dubious at best), the Accurate 8 soil pH probe is the ticket- (Control Wizard product)..... as GA6 mentioned, soils have pretty crappy for quality these days,.. OF in particular has shown serious off-pH issues (low 5's, for fucks sake! ).... So, all this said, first clue we need solid confirmation on is the soil pH accuracy, pending what you tell us about the pH meter and soil pH test kit,...