Looking for expert or pics of mosaic virus

Hi Hibbidy,

I think that you were right about tmv. It seems like it may be running loose out here in northern cali.

We need some feedback as to how your cleanup worked.

This is a very nasty virus that is very difficult if not impossible to irradiate. It is by design about the perfect virus.

It does result in very low yields and extremely poor plant growth.

Indicas are less at risk as they produce higher thc levels early on in the flowering cycle which acts as a anti viral agent. Sativas are ravaged as they do not have high levels of thc early on in flowering to protect them.

It gets passed on into the seeds. Once a plant is infected it is nearly impossible to preserve that plants genetics if you don't have them backed up elsewhere.

Again, any feedback on the results of your sterilization effort are greatly appreciated.

Hi

I grow outdoors extensively when not in prison on cultivation charges. Cannabis sativa spp. is very susceptible to a variety of viral diseases, most of them giving symptoms similar to TMV. I have found roses to be far worse than any other plant for harbouring mosaic viruses. TMV is misleading because it or a very similar form (probably just a slight mutation) infects tomatoes, cucumbers and a variety of other garden plants. Like most viruses in plants and animals it has a dormant form and can be carried without showing signs. Some plants are also naturally resistant.

It affects cannabis plants most badly when they are young and/or weak. Aphids (and presumably whitefly) spread the disease like wildfire through a crop. If the virus has not hit the growing shoots especially hard (as it tends to do unfortunately) then you can grow a plant through the disease if you keep it very healthy, just like any organism with a non fatal virus. It will still carry the virus though.

It DOES NOT necessarily carry in seeds but may do so just like any other virus in any organism. For example a mother with AIDS will not necessarily pass it on through pregnancy to an unborn child but there is a good chance that she will. There are strains of cannabis out there now which have viruses genetically fixed through intensive inbreeding and these manifest when the plants are under stress.

I have never ever seen these type of viruses carried through smoking tobacco or handling tobacco and to the best of my knowledge they are phloem borne so simply touching a plant when you have the virus on your hands would not spread the disease. It has to get into the sap, usually through sap sucking insects, a wound or on infected secateurs.

Aphids are an absolute nightmare outdoors with seedling stage plants. They suck on every damn sort of plant in the garden or forest and end up carrying a plethora of viral diseases around with them. A single suck from a single aphid can kill a cannabis plant depending on what the little beast is carrying. The healthier the plants then the better they can withstand attack.

Cannabis plants are actually more susceptible to some of these viruses than the normal host plants (ie roses, ornamentals, tomatoes, cucumbers, etc) because they have no genetic immunity through constant low grade exposure through generations.

There is no cure once a plant has it. You either try to help the plant fight it by keeping the plant healthy (just like a human with the flu) or destroy the plant. If it is a rare strain you really need to keep then you have to try and breed in generational immunity. This means get some genetics into that line which are either totally resistant to the virus or can carry it as a recessive gene in which case it will not harm the plant. Just like some humans can carry the AIDS virus or HEP virus but not be infected by it.

That is the current state with some cannabis strains as I outlined above. They carry the virus as a recessive gene but can still spread it to other plants through aphids etc which may then show signs of the diseaese.

hope this helps.

CannabisNZ.

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