Starts with Yellow Spots on Leafs ... Leafs End Up Dying

I'm growing (1) Robocrop Auto and (1) Blue Mammoth Auto in an indoor 4'x4'x7' grow tent using a hydroponic system and GH Flora Series nutes along with Calimagic, Hydroguard, and Liquid KoolBloom (during the flowering stage only). Temps and RH are controlled very well with a variety of equipment. I've changed out the reservoir faithfully every 7 - 10 days since the start.

After the first few weeks, I started to see yellow spots on new leaf growth of the Robocrop but not the Blue Mammoth and researched the internet to try and determine the cause. Based on factors including the appearance and location on the leaf of the spots, I ruled out leaf septoria (and a few other possibilities) and honed in on "calcium deficiency". My tap water is less than 50 ppm TDS and I had not been giving any calcium supplement up to that point. I started using Calimagic (at first 5 ml/gal with every feed) and the after several days the problem seemed to go away for some number of weeks. However, now towards the end of my grow (last few weeks before I will need to chop), the problem has returned again and this time on both plants. I have even been giving them Calimagic on a daily basis (4 ml/gal) with every water top-off, thinking it still might be a lack of proper calcium. Each of the affected leaves gets worse until it turns completely brown and dies. I would estimate that approximately 15% - 20% of the total of all leaves exhibit this issue. It does not seem to be affecting the plant growth or yield as I have some mighty fine looking flowers/buds on both plants and trichome color indicates another week or two before chop.

Although I think everything will turn out OK in the end on this grow, I'm worried about subsequent grows having the same issue (and maybe not the same benign result). What could I be doing wrong here to cause this?

I'm including 3 pics that best show the appearance of the issue. Thanks in advance for any helpful hints!

... StudioMan

Figure it out?

Looks like it may be lack of calcium? It won’t fix the leaves that have already been affected but new growth should seem and stay healthy after adding some cal supplement such as cal/Mg, hope things go well dude!

ColoradoHighGrower said:

Figure it out?

Click to expand...

Nope ... never did. The involved plant just kept getting worse in appearance (ended up with almost the entire plant covered with the spotted, dying leaves) but grew some of the biggest buds and what is looking like the highest yield I've ever gotten from a single plant. I guess it was fortunate that the leaf spotting/dying didn't appear until the plant was several weeks already into flowering. I'm starting to flush at the beginning of next week so I can finally take her down, so in the end it's going to be a moot issue. But I sure wish I would have found a definitive diagnosis since I would prefer to avoid whatever it is in my future grows. If the same problem were to occur earlier on in the vegetative phase, I don't think I would be as lucky.

I had scoured the net for info and must've looked through hundreds of pics of what the effects of plant deficiencies, excesses, and pests looked like. I bookmarked a dozen or more "charts" like the one Blake9999 sent me below and just kept pouring over them to see what images looked like my plant leaves. The only two that came close were "Calcium Deficiency" and "Thrips". Since I had been feeding the plant Calimagic on a regular basis (5ml/gal. each reservoir change-out, as well as 4ml/gal every other every other day when I did water top-off), it surely was not a calcium deficiency. And I inspected leaf after leaf with a higher powered microscope (100x) and saw no indication whatsoever of any pests present.

I had taken one bud off the plant earlier this past week, dried it for 3 days and smoked it as a test. The results were surprisingly pretty damned good ... leaving me to believe that with proper drying/curing, this lady will have ended up doing her job quite well after all.

Only other option is chalk it up to bad genetics. I've had that in the past, even the clones showed the same symptoms. Destroyed them all and moved on with other plants.

blake9999 said:

View attachment 4083658

Click to expand...

Thanks, Blake! I have collected several similar charts in the process of investigating my problem (see my reply to ColoradoHighGrower above) but I really like the compact, concise and somewhat comprehensive nature of the one you offer here so it's been added to my "Education" folder.

StudioMan said:

Thanks, Blake! I have collected several similar charts in the process of investigating my problem (see my reply to ColoradoHighGrower above) but I really like the compact, concise and somewhat comprehensive nature of the one you offer here so it's been added to my "Education" folder.

Click to expand...

I got it from a post from another member. Found it very useful to share.

Tiffj said:

Looks like it may be lack of calcium? It won’t fix the leaves that have already been affected but new growth should seem and stay healthy after adding some cal supplement such as cal/Mg, hope things go well dude!

Click to expand...

Thanks for the response. I agree that the symptoms are "dead on" with calcium deficiency, but the fact that I've been feeding this baby Calimagic for some time now (e.g., months) in sufficient quantity tends to make me think the problem lies elsewhere.

Just on the off chance that someone might recognize the source of this issue based on seeing a few more pics showing the leaves at various states of the "yellow spotting", I thought I'd give it one more try before I give up and just move on to the next grow. Blake9999 may be right and it's just bad genetics but my curiosity is killing me!

I'm putting three pics here ...
1) Early_Middle Stage pic showing a leaf in the middle of the pic that exhibits "early" signs of the spotting. In the same pic, the leaf just to its left is showing "middle" stages of the spotting.
2) Middle Stage pic showing middle stages of spotting
3) Late Stage pic showing an almost total necrosis of the leaf.

I had considered leaf septoria as a possibility but the plant is an indoor grow ... and the classic "black spots" mixed in with the yellow on a septoria-infected leaf are just not there.

Bring back any memories anyone???

Man that is some crazy shit @StudioMan- I'm not experienced enough to recognise it, or tell if those are rare symptoms or not... i hope you figure it out though, just in curiosity too!