Yellow leaves, brown spots - is this a fungus?

• Granddaddy Purple

• Outdoor grow, Coast of Maine Stonington Blend organic soil

• 7 gallon grow bags

• well water from aquifer

Adding Ca/Mg, Grow Big, Recharge, ProTekt, one teaspoon each, once per week

I have eight plants growing. Three are dark green, bushy, and look fairly healthy. The others are lighter in color and their growth appears sort of stunted.

Some leaves have shown the yellow coloring and brown spots. I have removed and destroyed such leaves. Suspecting a fungus, I ordered neem oil and will treat all the plants. Does this seem like a rational diagnosis on my part?

Gdp will take everything s I seen.
Can it be nute from watering?

Growing outdoors, I would look at environment they’re in. Any difference in the sun light, water or heat they get?

A picture of the whole plant(s) might help us.

It’s midnight here as I’m reading your reply. I’ll post photos tomorrow.

The seeds all came in the same batch from ILGM. They were all germinated the same, transplanted the same, all went into identical grow bags filled with the same Coast of Maine soil, and they were all watered the same.

I have the photos. Here’s one of the three healthy plants:

And here’s one of the sickly ones (lighter green, more scrawny):

Here are four other fairly scrawny ones:


…and a close-up of one of those:

I’m bumming out. As I took those photos, I saw a brown spot forming on a fan leaf of one of the healthy plants. Ugh!

Does anyone know what that condition actually
is? Or why half of my grow op is so scrawny??

I don’t know what that sentence means.

The pictures of the damaged leaf look like something fell on it: bird poop, insect droppings etc. The general yellowing can be caused by damping off (too much water), out of PH range soil, nutrient def or other. Without any real information it’s impossible to help.

COPY/PASTE the below list into your forum post.

Answer these simple questions the best you can.
If you do not know, or do not use something; Just say so; Or post
NA (non applicable)

  • What strain, Seed bank, or bag seed
  • Method: Soil w/salt, Organic soil, Hydroponics, Aquaponics, KNF
  • Vessels: Pots, Grow beds, Buckets, Troths
  • PH of Water, Solution, runoff (if Applicable)
  • PPM/TDS or EC of nutrient solution if applicable
  • Indoor or Outdoor
  • Light system
  • Temps; Day, Night
  • Humidity; Day, Night
  • Ventilation system; Yes, No, Size
  • AC, Humidifier, De-humidifier,
  • Co2; Yes, No

Always try to upload a clear picture of any issues you may have to allow the community to assist you.

Add anything else you feel would help us give you a most informed answer should be included. Feel free to elaborate, but short and to the point questions and facts will help us help you in a more efficient manner :slight_smile:


This is definitely not something that has fallen on the leaves. Of the three healthy plants I have, two are just today showing the same sign. Here’s one that shows how it happens: a yellow patch appears on the leaf, then a dark brown spot occurs, in this case opening a hole:

I put a close up in the lower right corner of the photo.

Here’s another incidence of the problem on the other “healthy” plant:

All these plants were from the same batch of Granddaddy Purple seeds from ILGM. They were all germinated at the same time. (Only eight out of the ten seeds germinated.) They were transplanted into pots at the same time, then transplanted into 7 gal. grow bags at the same time. Same Coast of Maine soil, same watering, same notes, same everything.

I think this may be a fungus, probably alternaria from the photos of cannabis leaves I’ve seen that look similar. Is there anybody around who has experience with that?


Outdoor grows are funny. You have a bunch of pest activity going on and if your humidity is high maybe; but if so it’s exceedingly rare. Like TMV: we hear about it but it never shows.

Thanks for getting back to me, Myfriendis410. Is there anywhere you can suggest I go to find someone who has experience with alternaria?

Its very easy to grow its hard to make it die so pick this leaf of and go on.