Possible brown spot fungus - Cannabis Cultivation

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Dr. Penguin

Registered: 05/19/08
Posts: 1,036

Possible brown spot fungus

#292035 - 10/04/09 10:29 PM (15 years, 2 months ago)

Hi everyone, I've got a bit of a problem that I just can't seem to figure out.

How long has this problem been going on? Since Germination
What STRAIN are you growing? Nirvana PPP
What was the establishing technique? (seed or clone?) Seed
What is the age of your plants? Four weeks into flower ~7 weeks
How long have they been in the soil mixture they are in now? Since the start of flowering (~4 weeks)
How Tall are the plants? ~2-3 feet
What PHASE (seedling, vegetative or flower) are the plants in? Flower
What Technique are you using? (SOG, SCROG etc) Minor pruning
What size pots are you using? (Include how many subjects to pot) 1 plant per 1gal pot
What substrate/medium are you using? What brand of soil? Fox Farm Happy Frog
What Nutrient's are you using? AN full line
How much of each nutrient are you using with how much water? *Knowing the brand is very helpful* Medium fert strength as published by AN(all tested with TDS meter before application)
How often are you feeding? Once every third watering~every 1.5-2 weeks
What order are you mixing your nutrients? (example: veg nutes 1st, bloom 2nd ect) Generally, grow, bloom, micro, various additives
What is the TDS/EC/PPM of your nutrients used? Max 1400ppm
What is the pH of the "RUN-OFF"? 6.8
What method of pH test was administered? Using Strips? pH pen? GH drop kit
How often are you watering? When pots feel light, ~ every 3-5 days
When was your last feeding and how often are you feeding? 1.5 weeks ago
What size bulb are you using? 400w
What is the distance to the canopy? About 4-5" (Cool tube)
What is your RH Factor? (Relative Humidity) 50% +- 10%
What is the canopy temperature? <80f
What is the Day/Night Temp? (Include fluctuation range) 75-80f day 65-70f night
What is the current Air Flow? (cfm etc.) 170cfm inline centrifugal
Tell us about your ventilation, intake exhaust and when its running and not running ? Exhaust runs 24/7, pulls through cool-tube and exhausts through a scrubber at the top of the cab. The intake is a baffle system on the bottom of the cab so air is taken in and spread to the outer edges of the cab (2' x 1.5').
Is the fan blowing directly at plants? No
Is the grow substrate constantly wet or moist? No, soil is allowed to dry between waterings
Is your water HARD or SOFT? Slightly hard (300ppm)
What water are you using? Reverse Osmosis (RO)? Tap? Tap
Are you using water from a water softener? No
Has plant been recently pruned, cloned or pinched? Cloned right before flowering
Have any pest chemicals been used? If so what and when? No
Are plant's infected with pest's? Minor fungus gnat population
Additional information: Symptoms occur primarily on older growth and fan leaves. This has been an ongoing problem since germination of the seeds but strangely enough the clones do not exhibit any of the same symptoms despite identical growing conditions (isolated from the plants in question). Originally I suspected over-fertilization, upon which I cut out my feedings; the primary symptoms did not exhibit any changes (for better or worse) but after 3 weeks the lower leaves started to develop suspected N deficiency so I resumed my feeding. I considered PH problems causing lockout but my runoff is at a nice healthy 6.8.

I have not completely ruled out nutrient imbalance but at this point I don't find it likely. If you check the photos I have provided you will notice the older effected areas have developed raised brown patches leading me to believe it is some kind of brown spot fungus. I have never encountered this problem but maybe someone on here has that can help confirm my suspicions.

I have examined the leaves under magnification and I can see what I believe are ascospore fruits but due to the low quality device used, the resolution is not enough for me to confirm that with certainty.

Any help will certainly be appreciated. Thanks!

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* My Cab
* How to Build a Grow Tent
* Fan Speed Control 101
* Easy Butane Extraction
Not responsible for advice not taken.

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FurrowedBrow
Free yourself from yourself

Registered: 04/20/08
Posts: 12,045
Loc: Carpal Tunnel

Re: Possible brown spot fungus

[Re: Dr. Penguin]
#292042 - 10/04/09 10:32 PM (15 years, 2 months ago)

I feel like i just looked at a really nasty STD picture man. THat's horrific! I'm sorry. I wanted to express my sympathy (and empathy). the perils of the hobby. :sad:

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