Is this a calcium deficiency?

[HutchBenedict]

I have been feeding my plants MC for a couple of years now but for the last few plants I've been getting severe yellowing starting with lower leaves.

Since I'm quite experienced with MC deficiencies seemed to be off the table so I looked at fungus gnats but my yellow stickies are clear and I've dried it out several times. So I looked at septoria. From what I can tell this ain't that. So what is it?

Here's the same plant a little later on. Those old leaves were removed but as you can see it's starting again.

The MC I am using is the ground-up version (3.5?). I am now beginning to wonder if perhaps the calcium has become un-homogenized and fallen to the bottom of the bag or something. I have added cal-mag to the feed today to see if that helps, but I would be grateful if someone could verify that this looks like classic calcium deficiency or not.

 

[Emilya Green]

no, its too early for calcium issues and since calcium is a non mobile element inside the plant, it presents only in the upper growth. This looks more like magnesium to me and an indication to use more MC. The extra mag in the calmag should help with that problem, but then the balance of MC is messed up. Remember the little advice they give about how to manage the MC dosage... go for the green, and any leaf damage indicates a need to adjust the application rate.

 

[HutchBenedict]

no, its too early for calcium issues and since calcium is a non mobile element inside the plant, it presents only in the upper growth. This looks more like magnesium to me and an indication to use more MC. The extra mag in the calmag should help with that problem, but then the balance of MC is messed up. Remember the little advice they give about how to manage the MC dosage... go for the green, and any leaf damage indicates a need to adjust the application rate.

Makes sense, but why is this happening so early? I'm at 4grams/gallon already (day 31) and was at 3gr/gal when the first picture was taken on day 14. I wonder if it is the ground-up version I am using? I usually scoop it from the bag into a jar so I'm not introducing too much moisture into the bag. Could it be as simple as shaking the bag up to re-mix the chemicals before using? Have you ever heard from anyone else using the ground-up version?

 

[Emilya Green]

Sorry, I can't answer these questions for you... I just can see what the leaves are telling me from your pictures. I got away from MC before they got to the ground up version, being frustrated that they kept changing their formula, kept not sponsoring the hard working members here that are trying to make their confusing product work, and kept their instructions so vague that a new grower was likely to get in trouble using their product. Plenty of folks are still using this stuff and getting good results from it, and I am sure that one of them will stop by to help out.

 

[HutchBenedict]

Sorry, I can't answer these questions for you... I just can see what the leaves are telling me from your pictures. I got away from MC before they got to the ground up version, being frustrated that they kept changing their formula, kept not sponsoring the hard working members here that are trying to make their confusing product work, and kept their instructions so vague that a new grower was likely to get in trouble using their product. Plenty of folks are still using this stuff and getting good results from it, and I am sure that one of them will stop by to help out.

Ok, thank you very much for taking the time. I think you are right about it being a magnesium deficiency rather than calcium. That really helps. I'll either switch nutes or figure it out but at least now I know what the problem is.

 

[FelipeBlu]

I have been feeding my plants MC for a couple of years now but for the last few plants I've been getting severe yellowing starting with lower leaves.

Since I'm quite experienced with MC deficiencies seemed to be off the table so I looked at fungus gnats but my yellow stickies are clear and I've dried it out several times. So I looked at septoria. From what I can tell this ain't that. So what is it?

Here's the same plant a little later on. Those old leaves were removed but as you can see it's starting again.

The MC I am using is the ground-up version (3.5?). I am now beginning to wonder if perhaps the calcium has become un-homogenized and fallen to the bottom of the bag or something. I have added cal-mag to the feed today to see if that helps, but I would be grateful if someone could verify that this looks like classic calcium deficiency or not.

In the last photo, I see a lot of what looks like pest debris(?) on the top of the affected leaf. Also, the yellow stippling along veins concerns me. Have you checked for pests with a loupe?

 

[HutchBenedict]

In the last photo, I see a lot of what looks like pest debris(?) on the top of the affected leaf. Also, the yellow stippling along veins concerns me. Have you checked for pests with a loupe?

Thanks for looking. I have checked with loupe and can't see anything. There is a lot of debris due to recent re-potting though the tiny black items could be from insects. Here are some pics

I have sprayed with neem oil a couple of times but the yellowing continues.

 

[FelipeBlu]

Doesn’t look good, amigo. @Emilya - mites?

 

[Emilya Green]

Doesn’t look good, amigo. @Emilya - mites?

egads... yes, a bad case of them too. @Sierra Natural Science SNS 217c to the rescue!

 

[HutchBenedict]

Doesn’t look good, amigo. @Emilya - mites?

egads... yes, a bad case of them too. @Sierra Natural Science SNS 217c to the rescue!

Thank you folks! As bad as mites sound this is wonderful news to me since the mystery has been going on for quite some time!!!

But how can you tell? I have looked at all the little yellow dots quite carefully and they are all plant damage, none are alive. The white and black things are also inert objects. Even the little narrow brown items. They appear to be peat moss. Is it the nature of the plant damage that gives it away?

In the meantime I'm ordering the SNS 217c today if they ship to Canada! Also off to do a bit of mite research.

 

[FelipeBlu]

A couple photos show what looks like tiny light green critters and some possible molts, but yes, it’s mainly the nature of the damage - the yellow stippling following the veins.

 

[HutchBenedict]

A couple photos show what looks like tiny light green critters and some possible molts, but yes, it’s mainly the nature of the damage - the yellow stippling following the veins.

Yikes, I'm feeling sick to my stomach. Was just reading up on cannabis mites...but, yeah, that's mites. Anyway, mystery solved. Thank you.

 

[FelipeBlu]

You’re welcome

Clean and nuke - repeat after 7 days.