What kind of deficiency is this?

Hello guys,

I'm trying to isolate the problem, but can't find any solution.

I saw yellow spots on some big leaves of my Moby Dick XXL AUTO plants. They are in the flowering stage.

Watering/Fertilisers: 50% net water (sink) and 50% demineralized water; adjusted to pH 6.5 and E.C. 0.3-0.4, plus 1 mL of Alga Bloom in 2 L of water (1 irrigation with only water and 1 with the fertiliser). I'm planning to scale up with nutrients slowly.

Had a EC issue a few days ago, due to a salt build up in the soli, so I flushed the soil with a balanced solution of demineralized water and normal water, adjusted to pH 6.5 and EC 0,2, containing Alga Bloom to replace the old salts.

A few days ago, some small yellow spots appeared, on the big leaves. In 3-4 days, the small yellow spots turn in a necrotic area of the foliar tissue. And I start to see the small spots on the upper big leaves of the plant. Plus the necrotic area grows day by day.

PICS BELOW

Could you please help me figuring out if it's a deficiency of some kind? It doesn't look as a Calcium deficiency, as my net water contains it a lot (that's why I mix it with demineralized water).

Thanks a lot, hope you can help me.

The dots look like a pest. Carefully inspect the undersides of the leaves for mites or other bugs.

I would agree with Lester, This doesn't look feed related. atleast not to my eyes.

on second look the second picture, top right corner there is a white dot on the background leaf.. Looks like a bug to me but with the resolution of the picture i can't quite tell.

a x30-x40 loop would be highly useful here.

Lester Beans said:

The dots look like a pest. Carefully inspect the undersides of the leaves for mites or other bugs.

Click to expand...

Thanks a lot for the reply Lester Beans. It actually doesn't look as a classic deficiency. On the other side, it doesn't seem to show a regular pattern of spots, as a pest-related disease.

Also, the spots are only on the Moby Dick XXL, not on the Bloody Skunk. That could be explained by a more pest- or deficiency-sensitivity of the strain.

I'll try to look at the leaves more carefully. Unfortunately, I do not own a microscope or lent.

Could be a pH variation in soil? Or a mobile element being locked or over-transported in your opinion?

I'll let you know if I can find a lent. Thanks really much for your help

Maple_Flail said:

I would agree with Lester, This doesn't look feed related. atleast not to my eyes.

on second look the second picture, top right corner there is a white dot on the background leaf.. Looks like a bug to me but with the resolution of the picture i can't quite tell.

a x30-x40 loop would be highly useful here.

Click to expand...

Thanks

I'll try to find a lent to inspect the leaves. Damn!

But, considering that at a first look, I can't see insects or molds and as only one strain is being actually suffering from it, could be a virus. Not sure at all, but still. So the 2 main hypothesis are:
- some sort of pest: excluding molds (low RH and not shown a regular pattern of growth)
- pH fluctuations due to my pH down manufactured by General Hydroponics

Other ideas are still appreciated...Thanks

Lester Beans said:

The dots look like a pest. Carefully inspect the undersides of the leaves for mites or other bugs.

Click to expand...

I have to 2nd that.

My first thought is to check for the possible presence of bugs. If there are bugs there most likely are not that many yet.

Although some of the spots, the larger ones, don't really look like bug damage. Those big spots look kind of like a Phosphorus related spot(s)

You say you are PH'ing your solution at 6.5 for soil? What is the starting PH of your water?

Ganoderma said:

I have to 2nd that.

My first thought is to check for the possible presence of bugs. If there are bugs there most likely are not that many yet.

Although some of the spots, the larger ones, don't really look like bug damage. Those big spots look kind of like a Phosphorus related spot(s)

You say you are PH'ing your solution at 6.5 for soil? What is the starting PH of your water?

Click to expand...

Thanks Ganoderma. I'll go to buy a lent tomorrow, checking for bugs. I'll let you know what I see.

The funny thing is that I have the two Moby Dick plants far away each other. And the Bloody Skunks in the middle. So it appears to be a strain-specific phenomenon. Who knows.. Thanks to every one. I'll keep the post updated.

About phosphorus, it is probable.

My house water has pH=8, EC=0.6, so I balance it with demineralized water and pH down by GH.

The thing has developed like this:
1) small irregular yellow spots on the big leaves below
then
2) the spots grew and the necrosis of the tissue area began
then
3) small spots spreading through the big upper leaves

The pattern repeated on the other plant, the Moby Dick. Read somewhere that the Tobacco Mosaic Virus is virtually able to infect cannabis plants.
This, summed up to the low genetic stability of some autoflower strains and seen that the phenomenon is repeated through only one strain, makes me think.. I'll try to read something more about this.

After checking for bugs, if I can0t find a solution, I'll try to contact Dinafem. So maybe we can help people having the same problem, if it's a strain-related stuff.

Thanks for sharing your experience