Can anyone tell me what is the most likely cause of this?

[TF Leary]

7wk old white widow in a DWC. These spots started out slowly on my lower leaves and now have exploded all over the plant, except for the brand new leaves. My first thoughts were possibly a potassium or calcium deficiency. I haven't been able to resolve the problem by trying to correct either of these so far. Any suggestions?

 

[Hawzzy]

How bout a little more info...nutes...water. ..are you paying attention to PH...grow medium etc. A pic of the whole plant. Im no expert but grow in dirt and dwc and have had a few problems that beat a couple plants and that I managed to beat with research and help from this helpful bunch.

 

[vostok]

I haven't been able to resolve the problem by trying to correct either of these so far. Any suggestions?View attachment 3624935

Your image '/necrotic-spots-jpg.3624935' is just that ...necrotic

in most cases caused by an excess of (N) in your dwc at week 7 most plants have fallen to senescence

best to flush no nutes until you have seen a positive recovery about 5 days

then re feed at 50% less no (N)

good luck