I edited my post above with specific reference to the photos provided but the board booted me off with an Admin message about edits not allowed to take more than ten minutes. So I try again...

Looking at the photos I have to say those plants are not healthy, at least not to the level I would like... in terms of growth, nutrients etc. Something is out of whack.

That doesn't mean it isn't a virus. As I said above a virus is most virulent at attacking plants when they are growing poorly. It is impossible to pick the specific problem just from photos but I have seen those type of symptoms many, many times before. It could be nutrient lockout as there are definitely signs of nutrient deficiency (possibly Boron) in some of those plants but that could just be a symptom of something else. Nutrient lockout can be pH related but it can also be caused by poor soil aeration or soil that is too cold or even nematodes chewing on the roots. Roots should be white and healthy looking and soil (or any growing medium) should smell good not bad.

The fastest way to diagnose nutrient deficiency is a simple broad spectrum foliar fertiliser spray. It saves trying to identify a specific nutrient issue because why should just one specific nutrient be locked out anyway? Nobody deliberately leaves Boron or Manganese out of a soil mix so a lockout is usually a bigger problem.

The downside is that many deficiencies are similar to toxicities in terms of the symptoms. Toxicities are a nightmare because it means flushing a mix and that isn't always practical. Some of those symptoms in those photos could just as easily be a deficiency like Boron or just as easily be a toxicity of one of the main NPK elements. N in particular can burn leaf edges like that.

At the very least I'd look into air flow also... just to strengthen plants overall and keep C02 circulating. Humidity is only an issue for indicas. True sativas come from tropical rainforest where humidity is usually around 90% and it doesn't worry them in the slightest. They love it and prefer it but they still need air flow. There's a big difference between humidity and air that is simply stale.

The amount of light is also very important with all cannabis plants. The more the merrier. If you look at real commercial operators they flood rooms with 1000W plus lights to get healthier plants. I've found as light wattage drops then the plants become more prone to disease and growth problems.

I have seen the symptoms your plants display in the photos many, many times but that doesn't make it easier to pick. For example even a light accidental spray of Glyphosphate (weed killer) would cause those exact symptoms also. It's like humans would sweat, shake, maybe get a rash for a lot of different reasons from a cold, the flu, at least ten different diseases, poisoning, allergy etc, etc.

Plants are the same. They respond in predictable ways when under stress but as to the cause of the stress... it's not always easy as some so called "plant experts" make out.

If I had to make a guess from those photos I'd guess that there is a virus at work but it is being accellerated by something else not quite right in terms of plant health and growth.

CannabisNZ