Possible calcium lockout or start of Molybdenum??? - Recommendations appreciated

[MNTGrown]

Howdy thanks for giving this a quick read.

I just started my 4th week of flower on an outdoor grow and noticed the rust colors on my leaves seen in the pictures below. This problem is only occurring in the middle of the plant, new growth shows no signs of damage. The damage seems to be occurring mainly on my Indica strains, which typically show deep color changes later in life. I have also had the onset of fall where I am and seen temps as low as 45 degrees at night.

In the last week the plants have received a 8 gallon fertilized watering, close to an inch of rain, another 8 gallon fertilized watering, and then another .5" of rain, these are in a 100 gallon smart pot using a peat based soil. The fert mixes are at a 6.2 or 6.3 ph.

The soil test around a 6.8 - 7.1ph.

The first pic is of a plant 4 days ago showing no marking. The next 3 pictures show the damage that has shown up today, 2.5 days after my last fertilized watering, and the last picture is a shot of one of the whole plants with damage. (Pic three also shows hail damage from weeks past.)

 

[Seamaiden]

Hm, that looks like classic Ca-, but if it's only just starting to occur and it's showing mid-plant, that tends to disallow Ca-. I've seen Mb- once and it was likely tied to super-low pH, and it looked nothing like what you're showing us here.

You haven't mentioned what you're actually feeding, so I can't make recommendations on how to adjust that, I honestly feel more comfortable making my observations and letting folks go from there, but in ANY event! Most mid-plant problems I've experienced were K-. But I don't recall that ever looking like what you're showing.

Knowing that Ca is immobile, I can't say anything you do will correct what you're observing. You can up the Ca and stop progression, and if it stops then I would suggest you've found your culprit. If it doesn't, then I would start thinking about K here, even though it looks nothing like any K- I've seen. At least it's mobile though and you can more definitively stop progression.

Finally, perhaps it's time to go ahead and think in terms of micronutrients and balances instead of deficiencies. Do you use anything like Azomite that will provide micros?

 

[MNTGrown]

Thanks for the input. No progression yet. I do have azomite mixed in my soil bases and use Veganic Special Sauce very 7 to 10 days mixed in at about .5 cups per 50 gallons and around 8 gallons per plant.

 

[caveman4.20]

Is this eaten up looking damage only on discolored leaves or on solid green leaves aswell?

 

[MNTGrown]

Thanks for your interest Caveman those spots are from a hail storm I had a few weeks ago. It really put the damage on my western facing plants.

 

[We Solidarity]

if it's a nutrient deficiency it's more than likely calcium (although at 7 there should be calcium available) however those look like burn spots, out towards the edges of the fan leaves (when plants have excess nutrient they move it to the edges of the leaves where transpiration happens at a faster rate, similar process to guttation but for nutes instead of water). How strong is your feed? Peat based soils can hold a lot of nutes.

 

[Seamaiden]

^^ something I did not know!

 

[toquer]

if it's a nutrient deficiency it's more than likely calcium (although at 7 there should be calcium available) however those look like burn spots, out towards the edges of the fan leaves (when plants have excess nutrient they move it to the edges of the leaves where transpiration happens at a faster rate, similar process to guttation but for nutes instead of water). How strong is your feed? Peat based soils can hold a lot of nutes.

So then it's more am imbalance than a deficiency? Excess of several cations interfering with Ca uptake?

 

[Seamaiden]

Indeed. Let me post up something I saw in one of my Acres, USA mags. Feeding is as much about balance and ratios as anything else.