It has been established that Figs (like many plants) can carry anywhere from 10-50+ different types of viruses. Leaf mottling/mosaic viruses include at least FLMaV-1 & -2, FMMaV, and FMV, plus a host of other co-viruses that may be triggers or modifiers. The "disease" can be the result of contamination by one or more of the viruses with a prevailing theory that certain combinations of viruses may be more pronounced (or damaging) than others. This may be a case like HIV+Pneumonia where FMV creates an immune threat that allows less lethal diseases to do real damage. There have been global studies about FMV and related viruses. Here is an abstract for an Egyptian study which shows that most (95%) trees (in the study) have some form of mottling-related virus, but not all trees have the same virus: http://www.fupress.net/index.php/pm/article/view/8741/9054

Certainly global trade and exposure to foreign strains could overload a plant's ability to cope: not just exotic strains of mosaic/mottling, but other viruses in general that could be contributing to the damaging aspects of the disease.  As to what we should do at this point, who knows. Global and domestic trading and exposure seem so overwhelming at this point--and there is so little information as to why some cultivars take a beating while others resist--that it's hard to say. Personally, I separate cuttings from "outsiders" away from my asymptomatic inground trees: grow in separate rooms and place potted plants in different areas of the yard. But there's no way to know if what I'm doing is effective or even necessary.

You kids should check this out if you have not seen it. http://figs4funforum.websitetoolbox.com/post/in-defense-of-fmv-infection-6035851

For a better idea of why people seem downright offended over any difference in opinion on this subject and others look up the term groupthink. 

I have fig trees that have never shown FMV before but are showing it this year.  I also have trees that have shown it in the past but that look FMV free this year.  It leads me to believe that all trees have it but that whether or not they show it varies from year to year.  Some varieties will show it every year regardless, but for most trees it seems to come and go.

pete, i would never attack your qualifications.

i was just making the point that cuttings from very old trees all seem to beclean.

The assumption that all sucking insects transmit FMV, is not demonstrated as fact.
What is known for sure is that fig mites are specific for fig trees and move the virus from tree to tree.
The conclusion:No fig mites in your area due to Winter cold!---No FMV spreading from tree to tree,unless:
You graft diseased scions on a healthy tree.

how about dirty tools, herman?

merely because moving fmv by other insects hasn't been demonstrated doesn't mean it doesn't occur.

"The conclusion:No fig mites in your area due to Winter cold!---No FMV spreading from tree to tree,unless:
You graft diseased scions on a healthy tree."    


Or unless you receive plant material from a location w living mites in spring or summer - and the mites survive just for a few months in your location before it gets cold.  All the more reason to quarantine new plants coming in.

I am in California. Some of my plants appear disease free, but I assume all my plants either have FMV - or will soon get it. I give them relatively good care so they grow well and remain strong. But some do grow better than others even though my basically frost-free climate is very forgiving of plants that have been weakened.

Unless you have each of your plants tested, assuming they don't have FMV just by looking is, at best, a guess. And tissue culture plants are no guarantee.

gina, my theory is that if a plant never shows visible signs of fmv, it's fine. 

sure it may be infected but since there are at least 4 varieties  of fmv n those can occur in the same plant at the same time, i think
if fmv exists in a plant but never shows, for all practical purposes it's clean.

my concern is vigor. i just burn plants that show visible signs,

it seems to be working. my plants don't show fmv when stressed. before i invest time in a plant i put it thru water stress, withholding water
time after time. if new leaves show no fmv, i don't care if a lab test could detect it.

susie, no problem. i don't even work in that field... 

About dirty tools,reports are variable,some say,it will not spread some say it will.
I do wash my cutters any time I prune live wood on different trees just to be sure.
Of course bringing in your Orchard new trees in late Spring or Summer can bring fig mites,that will do damage to your trees all Summer long,till they die ,the next Winter.
It is a more complex subject,that every one,can have an opinion,on how to avoid it
In short,it is like that.
Fig mites spend Winter under dead debree close to surface ,under the tree.
In Spring when soil get warm,they move up inside growing buds ,when they start opening.
If you buy a tree ,late in Spring and it comes from a climate where the fig mites live,an insecticide,that will kill the mites should be used.
Of course ,the insecticide has to be tolerated by fig tree.
I have no idea what insecticide will do ,but I am sure someone ,in the industry know.

Mjbaransky,
Its possible that your Black Mission Fig has Fig Mosaic Virus (FMV) but not all Visible Fig Mosaic Disease (FMD) symptoms are caused by FMV. Many are caused by incorrect pH, nutrient deficiencies, Soil Aeration and or Watering Issues. There should be a distinction made between FMV and FMD.

Since the spread of FMV is caused by known variables, Fig Mites and Grafting and possible variables IE. infected tools,  isolating the suspect fig tree may provide peace of mind. Providing the best available culture will then ensure that the fig tree will grow optimally. If it is non productive, you can provide the answer to your own question to destroy it or not.

The procedure of isolating new plants before introducing to existing plants should also help to reduce any possible infestation of Fig Mites, along with a simple procedure of dusting the plants with Food Grade Diatomaceous Earth to kill any mites and chewing insects that may have hitched a ride.

Good Luck.

BTW, since most studies that have been done on FMV has occurred in locations that have active fig mite population, the data has been somewhat skewed and will actually show that most trees in that location have the viruses, because it only takes one (1) feeding of an infected mite to spread the virus, and the virus is not spread by seeds. IMO, This may also explain why there may have been populations of uninfected fig trees in the Mediterranean, because seeds may have been spread by bird to locations (colder regions) where the fig mites didn't exist.

pete s, would you please expound on the difference between fmv and fmd?

i thot they were the same thing, so i'm missing something.

Susie,
FMV (viruses) may sometimes cause Leaf and fig deformation and mottling which is a symptom that is also known as FMD (Fig Mosaic Disease).

Deformation and mottling (FMD) can also be symptoms of poor Culture, including incorrect pH, nutrient deficiency, poor soil aeration and or improper watering.

<Edit>
Yes, A fig tree may have FMV, but it may not be severe enough or it may not have a large enough "cocktail of viruses" to exhibit FMD symptoms.

so, if a tree has fmv, fmd means it's bad enow to show?

thanks. that's a valuable distinction, pete.