Black leaves

[cool09]

I have a very healthy WW plant 4 wks into flowering. Some black marks are showing up on a couple leaves in no particular pattern. (Lights are close (13"-15"), cooled and not emitting any heat on plant. pH is 5.8 so I need to raise it. Humidity never gets above 35-55% or so.) I read that black marks may be a fungus. (Leaves in right photo are at top of plant and are closer to the HPS. Left photo are in middle of plant.) Ideas?

cool09 Reviewed by cool09 on 04-01-2013. Black leaves I have a very healthy WW plant 4 wks into flowering. Some black marks are showing up on a couple leaves in no particular pattern. (Lights are close (13"-15"), cooled and not emitting any heat on plant. pH is 5.8 so I need to raise it. Humidity never gets above 35-55% or so.) I read that black marks may be a fungus. (Leaves in right photo are at top of plant and are closer to the HPS. Left photo are in middle of plant.) Ideas? Rating: 5

[Mal420xl]

http://boards.cannabis.com/plant-pro...ing-forms.html fill that out its faster that way. it almost looks like the onset of fall color when you grow outside or have cool temps. but yours is more blotchy lookin. have you made any changes at all?

[cool09]

I have been moving the lights closer and closer the last 10 days after adding cooling to the hoods. Plants do not feel any heat from lights. (They are at room temp.) Started noticing black 3-4 days ago. (I had HPS very far away last mth or so - didn't know how to get them close until I got some advice in a Forum somewhere.) Using 2x250W on 10 sq ft or so.

[polishpollack]

Well, that's a new one. Please fill out the troubleshooting form and give as many detail as you can. I can't determine if it's a nute problem or disease like mold. Need more info, like what is your room like, if indoors. What and how are you feeding/watering and how often, etc.?

[polishpollack]

Don't bother, I think I found it, something called "canna rust," which has spots on leaves turning a brown-black color.
Canna rust, caused by the pathogen Puccinia thaliae, is a common fungal infection of Canna indica.

Read more: Common Fungi Responsible for the Spotting on the Leaves of the Canna Indica | eHow.com Common Fungi Responsible for the Spotting on the Leaves of the Canna Indica | eHow.com
canna rust - Yahoo! Search Results
Common Fungi Responsible for the Spotting on the Leaves of the Canna Indica | eHow.com

[Shovelhandle]

no
canna indica is not the plant we're growing here.
check out these photos that's canna indica

[Mal420xl]

i couldnt find anything valid for canna rust on mj. it either referred to the flower canna or was some bogus redirect. the info on canna rust says it starts orange then turns black and leaves die(on canna lillies). that looks like it starts light black or grey and gets darker. still need you to fill out the trouble shooting form to speed things up.

[polishpollack]

On another site, someone posted the same question. They said the leaves were turning black and something about being crossed with purple urkle and when people read that, they said, "clone it." It was noted as being black, not purple. Anyway, I've never seen black on a leaf before, but if the room has kind of high humidity, usually due to a lack of fresh airflow, then this most likely is a fungus or mold. A shame as it looks like a nice plant otherwise. Don't consume anything when you don't know what it is.

[Mal420xl]

whats the underside of the leaf look like?

[cool09]

I saw the same post about canna rust. Underside of leaves look normal. Think it must have something to do with bringing lights closer. Lower leaves show no black, Middle leaves - barely any black, Very Top leaves - maybe 60% of leaves are 20-30% black on topside. Plant looks healthy and green.

What is your experience level? Amateur

.1) Type and wattage of lights. HPS 2x250W
.2) Distance from tops? 15"-16"
.3) Reflector type? Bulb, Hood: aluminum sheet metal painted white & area surrounded w/thermal reflective sheets.
.4) Is there a consistent fresh air supply? Yes
.5) Do you have an exhaust fan and a circulation fan? Yes
.6) What are the bulb wattages, kelvin ratings, and schedule? 2x250W, 12/12

.7) Specific brand and type of soil. Foxfarm soil w/some manure, perlite, sand added
.8) Size of container? 3-4 gallon
.9) Did you use peat pucks (or similar) to root clones or germinate seedlings? No

10) Source of water? Distilled (bottled)
11) Method of checking water ph. Pen
12) Method of adjusting water ph. add Ca (dolomite lime) to raise (Haven't needed to adjust pH until this week.)
13) Specific brand and N-P-K ratio for each bottle. Foxfarm nutrients per feeding schedule.
14) How often are you watering between feedings, and how much per watering? Water once between feeding, water until runoff.
15) Any additives or tea's? (Superthrive, CalMag, molasses, Mother's Earth...) No
16) Are your ph levels stable, or do they fluctuate? Stable, around 6.4-6.6
17) What is your ingoing water's ph? ...your runoff ph? 7.0, Runoff - never check.
18) Do you foliar feed? If so, with what, how often, and at what time do you spray? No

19) Indoors or outdoors? Indoors
20) What size of closet, room or hut? 10-11 sq ft
21) What are the temps and humidity levels? DAY: 70 deg, 30-50% Humidity, NIGHT: 62-64 deg, 30-50% Humidity.
22) Have you seen signs of insects in the growroom? No

23) What strain are you growing? (Indica dominate or Sativa dom?) White widow
24) From seeds or clones? Seeds
25) Is this an autoflower strain? No