I found an abstract of a journal article that seems to support a theory proposed by Herman2 and robertharper in an old thread--stress influences the development of fig mosaic virus (FMV) in cultured trees.  “Stress-related expression of virus symptoms in fig (Ficus carica L.)" was reported in Israel Journal of Plant Science.  It documents a study in which scientists exposed Ficus carica to the environmental stresses of trellising and high temperatures in order to force expression of latent (dormant) FMV. 

Full disclosure: I didn't actually purchase/read the entire article, but starting this thread will give the information exposure in case others are interested in obtaining it.  I also posted a link to the information in an old forum thread where I had read a thoughtful discussion of why FMV expression seems to wax or wane depending on the environment in which the tree is grown. 

Here’s the link to the abstract:
http://www.sciencefromisrael.com/app/home/contribution.asp?referrer=parent&backto=issue,4,13;journal,26,45;linkingpublicationresults,1:300170,1  

Also the link to the old thread where the topic was discussed:
http://figs4funforum.websitetoolbox.com/post/Zingarella-5359540

I hope that the information is the scholarly confirmation that Herman2 wanted when he posted this (#17) in the old thread:

Mimi,
Good find!

I tried to attach the pdf but it exceeded the forum's size limit. Does anyone have a suggestion? Jon?

Better link?

http://www.sciencefromisrael.com/openurl.asp?genre=article&issn=0792-9978&volume=52&issue=2&spage=103

This recent article suggests that Fig Mosaic Virus (one of the viruses found in trees with Fig Mosaic Disease) is classified as a negatively stranded RNA virus-- Emaravirus and that the virus is present throughout the plant and is spread by a specific eriophyid mite, grafting, vegetative propagation (cuttings), but not seeds (although the virus was detected in seeds).

http://www.mdpi.com/1999-4915/4/9/1515/pdf

Other viruses have additionally been found in trees with FMD, particularly Closterviruses (esp. FLMaV-1--a Fig Leaf Mottle virus)  It was suggested they may play a role in FMV symptom expression. The article from Saudia Arabia suggests high temperatures play a role.

naldc.nal.usda.gov/download/47395/PDF

http://www.sipav.org/main/jpp/volumes/0307/030720.pdf

scialert.net/fulltext/?doi=ijv.2012.128.132&org=10

I assume that someone has tried grafting affected trees to F. palmata which is supposed to be immune, but I couldn't find it anywhere.

Scott,

thanks for covering my back and posting a good link to the article.  I also appreciate the additional information.  Wow!  Seeing all the viruses involved in fig mosaic disease makes me think we're really fortunate not to see more of it than we do...

The interesting thing for me was that the Saudi study found less FMD at high temperatures while the Israeli study found more.  I guess that just shows that one should choose their variants wisely--or suffer the consequences.  Since FMV appears to be present in all variants, your plant is just telling you it needs a better home when you see those yellow-spotted leaves.  




 

Hi Mimi,

Yes, I think in the Israeli study, the mosaic showed up after stressing the trees by bending the branches followed by high heat. Whereas in most of the other studies, heat lessened the FMD symptoms, but some of them say high greenhouse temperatures were selected for good leaf symptom development. I'm not sure what any of it means.

Other than heat (temperature), I wonder if shade/sunlight faciliates/inhibits FMV.