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Rust spots on leaves

  • by Help_Needed
  • Sep 06 2007 03:27 PM
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Posted 06 September 2007 - 03:27 PM

I just noticed these spots this morning. It's only affecting two of the larger fan leaves on a single plant. Both of the leaves are somewhat older, so this *may* be left over damage from my pH nightmare two weeks ago.

Any thoughts?

EDIT: Ok...I'm a newb lol. Grow details - hydro drip feed DWC system. pH is at 5.6 and TDS is at 920ppm using the Lucas Formula (top off meathod). Lighting is provided by a single 42w cool white CFL over each plant plus a couple of 36w daylight CFL's on the side. Res temps are at about 75. Room temps are averaging 80 - down to 75 during lights off, as high as 83 during lights on. Plants have been on 12/12 for about 10 days now.

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Posted 06 September 2007 - 04:26 PM

Could be many things. beginning of Nute burn ( try backin offf the PPM's a wee bit), ph fluctuation (your ph seems fine), ozone damage, potassium deficiency, calcium deficiency, fungal pathogens, viral pathogens, fugus gnats etc...

fungal pathogens often causes stem rots, & round leaf spots, concentric rings, necrotic discoloration, or wilt.
viral pathogens can inhibit chlorophyll formation, causing degrees of yellowing or redish/brown mottling, stunting, distortion, or dieback of part of the plant. Viruses usually debilitate rather than kill, as they are parasitic. or
Nematodes are microscopic roundworms that cause disease-like symptoms. Stem nematodes feed on stems and cause shortening of internodes. Root nematodes feed underground, damaging the root system ; this leads to moisture and nutrient stress which shows up as wilting and stunting or redish/brown mottling. Foliar nematodes cause angular leaf spots. or sucking insect feeds on plant fluids & can cause leaf spotting or stippling (aphids, leafhoppers, spider mites, other bugs), fungus gnats in a DWC system has been know to cause a rust looking affliction to the leaves from larve feeding on the tinyest of roots

inspect the res closely for almost microscopic critters feeding on the roots, or dead in the bottom of the res

viral pathogen or fungal pathogens can usually be dispatched with the use of 70% strength Neem Oil.....this I would try first, as there should be no ill affects to the plant with this treatment
I hope this helps you isolate the problem, keep us posted, with what you find as you begin to isolate the problem

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Posted 06 September 2007 - 04:44 PM

Could be many things. beginning of Nute burn ( try backin offf the PPM's a wee bit), ph fluctuation (your ph seems fine), ozone damage, potassium deficiency, calcium deficiency, fungal pathogens, viral pathogens, fugus gnats etc...


Dammit, Ganja, you're supposed to look at the picture and give me an easy answer like "It's a nute deficiency." lol.

Seriously, thought, thanks for the quick reply. pH fluctuation could very well be it, since I hat that problem a couple of weeks ago - where the pH dropped all the way down to 2.4 due to a defective pH meter - and the spotting seems to be on a couple of older leaves and this was also the plant that showed the most stress during the crisis.

I'll watch it closely, though, and if it looks like it's spreading to other parts of the plant, or to other plants I'll try to figure out what it is.

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Posted 07 November 2011 - 03:43 PM

everything work out?


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