Horizontal burning “grill marks” on leaves, blistering, and lesions.

[Irish Goodbye]

I am hoping to get some advice on what this could possibly be. I’ve been chasing the problem for the past few years, it comes up in many of my plants and I’ll be damned if I can sort out what is causing this. I’ve been through every damned nutrient deficiency table on the internet (which pretty much all seem to be the same thing cut and pasted) with no luck finding these grill marks.

The problem usually starts as slight blistering in the middle of the leaf that then progresses into fully open lesions or holes. This is not a bug, I repeat this is NOT a bug. I have inspected the tissue extremely thoroughly with a usb microscope. I am also fanatical with my IPM.

I almost always see this concurrently with these odd horizontal grill marks and general deformation of new growth. The leaf veins themselves become rusty and necrotic as well.

Symptoms are concentrated to the middle-lower foliage.

Medium is Promix HP/Coco Coir 50/50 mix. 2gal containers. Under 1000watt HPS, 32” from top of canopy. Temperatures are 77 lights on 68 lights off. Humidity right now is about 35-40% as I’m about to go into week 6 of flower, but these issues also happen in my veg room where my humidity runs about 60%.

Feeding GH Flora Series 3 part with 0.4EC of calmag added to RO water. Also using 1ml/gal of Potassium Silicate. Feed-water-water schedule at 2.0EC, ph 6.0.

Runoff EC hovers between 1.5-2.2 with a ph consistently around 5.6-6.2

 

[Perdido]

What about your night and day temperatures?

 

[Cvh]

Viral maybe? Something like Tobacco Mosaic Virus (TMV) perhaps?

5 Viruses to Watch Out for in Your Cannabis Grow | Modern Canna | MCS

Viruses exist on the edge between life and death. They are acellular, or nonliving, agents that require living organisms as hosts to survive. This is

moderncanna.com

 

[TanzanianMagic]

I am hoping to get some advice on what this could possibly be. I’ve been chasing the problem for the past few years, it comes up in many of my plants and I’ll be damned if I can sort out what is causing this. I’ve been through every damned nutrient deficiency table on the internet (which pretty much all seem to be the same thing cut and pasted) with no luck finding these grill marks.

The problem usually starts as slight blistering in the middle of the leaf that then progresses into fully open lesions or holes. This is not a bug, I repeat this is NOT a bug. I have inspected the tissue extremely thoroughly with a usb microscope. I am also fanatical with my IPM.

I almost always see this concurrently with these odd horizontal grill marks and general deformation of new growth. The leaf veins themselves become rusty and necrotic as well.

Symptoms are concentrated to the middle-lower foliage.

Medium is Promix HP/Coco Coir 50/50 mix. 2gal containers. Under 1000watt HPS, 32” from top of canopy. Temperatures are 77 lights on 68 lights off. Humidity right now is about 35-40% as I’m about to go into week 6 of flower, but these issues also happen in my veg room where my humidity runs about 60%.

Feeding GH Flora Series 3 part with 0.4EC of calmag added to RO water. Also using 1ml/gal of Potassium Silicate. Feed-water-water schedule at 2.0EC, ph 6.0.

Runoff EC hovers between 1.5-2.2 with a ph consistently around 5.6-6.2

That's leafhopper damage.

Learn How to Grow Marijuana - Bigger, Better Buds

www.paramountseedfarms.com

Maybe thrips.

https://www.biorxiv.org/content/10.1101/2020.05.11.088997v2.full

Leafhoppers jump on top of the leaf and start eating.

Basically whenever you see a hole in a leaf, it is most likely an insect did it. The size of the hole is a clue to the size of the insect.

By the way, there is nothing unusual for cannabis to have insects on it. Most of the plants' defenses evolved to defend against insects and herbivores.

 

[Irish Goodbye]

Not leafhoppers. Doesn’t explain the burnt grill marks and I’ve inspected thoroughly for bugs. I deal with leafhoppers outdoors extensively so I’m familiar with the type of damage they produce.

Also, the holes begin as “blisters” that eventually pop open and leave holes.

I can see it progress from day to day in the same spot until the lesions form.

It’s a head scratcher for sure.

 

[TanzanianMagic]

Not leafhoppers. Doesn’t explain the burnt grill marks and I’ve inspected thoroughly for bugs. I deal with leafhoppers outdoors extensively so I’m familiar with the type of damage they produce.

Also, the holes begin as “blisters” that eventually pop open and leave holes.

I can see it progress from day to day in the same spot until the lesions form.

It’s a head scratcher for sure.

If it is absolutely not insect related - and there may be multple insects at work like leafhoppers and mites - then I would say as a second possibility, it could be potassium deficiency/lockout related.

Apparently potassium can also cause holes in leaves, and the serrated leaf edge damage is either potassium or magnesium deficiency/lockout.

"While true that holes in leaves can be indicative of a nutrient deficiency such as potassium, more often than not this leaf damage is actually caused by hungry herbivores."

Leaf Holes – Deficiency or Delicacy?

The sudden appearance of holes all over plant leaves can lead many hobbyists to assume they have a deficiency in their planted tank. The problem is that it is difficult to diagnose a deficiency just...

www.liverpoolcreekaquariums.com

I presume everything else is ok with runoff pH and EC.

 

[Irish Goodbye]

If it is absolutely not insect related - and there may be multple insects at work like leafhoppers and mites - then I would say as a second possibility, it could be potassium deficiency/lockout related.

Apparently potassium can also cause holes in leaves, and the serrated leaf edge damage is either potassium or magnesium deficiency/lockout.



I presume everything else is ok with runoff pH and EC.

Thanks for this. Yes, 100% it is not insects.

EC is pretty on point as I described in the initial post. I have never heard of K issues causing the holes. That is very interesting indeed.

I agree, I have felt it could be a potassium and/or magnesium issue as well, but the blistering holes is what really has me confused.

I’m wondering if perhaps the silica I’ve been using is causing some sort of chain reaction lockout issue. I only introduced it a few years back and never had these issues before I did. I know it can be finicky to mix properly without it precipitating out of solution and/or binding up other elements.

 

[Creeperpark]

You have leafminers-Agromzidae.
Leafminers feed within leaves, producing large patches or winding tunnels of dead tissue. The most common leafminer species in Minnesota vegetable gardens are the spinach leafminer and the vegetable (serpentine) leafminer. Leafminers do not affect plant growth but can damage the edible leaves of vegetables. Google

The Agromyzidae are a family commonly referred to as the leaf-miner flies, for the feeding habits of their larvae, most of which are leaf miners on various plants. A worldwide family of roughly 2,500 species, they are small, some with wing length of 1 mm. The maximum size is 6.5 mm. Wikipedia