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cis4elk

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Reply with quote  #1 
Let me preface with the following:
I realize we all have opinions on the FMV issue.  I am not asking for information to educate myself on the inevitable onset of mosaic virus which may or may not already exist in my trees. If anyone knows of links which may have some information to the persistence of FMV in soil it would be appreciated.

  I have been trying to find an answer to the persistence of the virus in the soil(especially frozen soil) and can't find much on it. It stands to reason that if a person is growing a plant in an un-natural environment, then the evolved diseases of said plant are going to suffer the consequences of the hostile environment as well.

I have found  University studies that state tobacco mosaic persists in soil and dead plant matter almost indefinitely. While cucumber mosaic apparantely does not persist much beyond the growing season. I have also found that some mosaic viruses over-winter in host plants. But nothing on FMV persistence. I fear this information may not even exist as of yet.

I grow my figs in pots and I have one fig tree which has the virus, and overcomes it. Last summer this fig's pot was partly buried in soil/mulch. The location was a very nice location which would be better for all of next years little up and comers which are rooting clones at the moment. But I don't want to infect my new babies if they are in fact clean.  I would prefer to move the tree with known infection farther from all my other trees; but if that is it's spot from now on, I guess so be it.

I am keeping the infected tree to see if overall this cultivar is a keeper for my tastes and regional preformance, it is also my biggest and the first fig tree I bought. I had another infected tree but I sent it to zone 3 to see if my parents can keep it alive before I give them something better.

Anybody read anything about this before?

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Dieseler

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Reply with quote  #2 
Its said not to ,  its within the fig plants limbs said to move slowly in plant and can be transmitted with  un-sterilized pruning shears and the famous bug that i will not try and spell.
DesertDance

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Reply with quote  #3 
What Diesler said!

Suzi

The soil issue is the dreaded nematode.

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MichaelTucson

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Reply with quote  #4 
Excellent question.  I'm not sure if it's been studied, but it's probably a fairly complicated question (or set of questions).  I suspect not definitively, if at all.  "Soil" is not well-defined.  To which materials in soil would you be referring?  Also, there are at least 8 different viruses identified (so far) that cause the diseases known as fig mosaic.  So it's possible that environmental conditions in which they survive may be different among the different viruses  (not to mention differences among different strains of the same viral species).  There are a few members on here lately who have been very good at searching the academic literature.  Maybe one of them will search the databases for this.  (DWD2, Harvey, and Bob C to name just a few of them).  Though I cannot answer those questions with any references, I have seen several papers that suggest a little bit of related information.
  - at least one of the viruses doesn't seem to be transmittable by soil.  (But that doesn't answer about all of the viruses, nor necessarily what constitutes "soil", though I'm confident that paper had a narrowly crafted claim about this).
  - infected trees that overwinter can come back in the spring with the disease still.  (Suggests that at least one of the viruses survives cold temps in the tree sap/tissue.  But how cold?  I don't know).
  - You didn't ask this, but I read in one paper that one of the vectors (the mite that's widely accepted as a vector) stays infected for its life, once it becomes infected.  i.e. At least this one insect vector starts out "clean" when hatched, but once infected that insect stays a carrier for its life... it did show that mite offspring started "clean" even from infected/carrier parents).
  - at least one paper suggested that there are lots of insects that can carry the virus from one tree to another (many vectors).

Still, an interesting question about whether the viruses survive in "soil".  But with so many variables, it's very complex.  I've discovered that 150-200 feet is not sufficient distance (from definitely infected trees) to keep "seemingly clean" trees from showing symptoms of the disease.  Probably because the vectors are ubiquitous.  It's also not clear if trees that are not showing symptoms are really "clean" or not.  But I have seen trees that showed no discernible symptoms for years, that then began showing symptoms after having infected trees placed about 150-200 feet away.  Which virus(es)? (I don't know).  So to your implied question of "how far to move them"... I don't think that is known.  It's not clear that all the vectors are known, but the range of individuals of known vector species is probably also not known.  So how far away would you move them?  I have no reference papers to point you to (and I doubt it's known).

Others in the northeast have reported heavily infected trees coming back much stronger and showing fewer (or no) symptoms after overwintering.  Whether this is because the tree was more mature and better able to resist whatever virus(es) it had, or because the cold weather killed some of the virus strains... well, who can say?  It would not surprise me if it is eventually found that some of these particular viruses survive freezing whereas others do not.  Somehow the cold climates seem to have more trees that appear not to show symptoms.  A few of the members seem to have collections that aren't showing symptoms.  (Maybe one of them will provide some insight).  

Your implied question (about keeping your maybe-clean trees "far enough away" from your definitely-infected tree) is one that I used to share.  But I've punted... I think that just isn't known yet.  (And it's possible the answer is another kind of punting:  don't bother trying).

Mike   central NY state, zone 5

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JoAnn749

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Reply with quote  #5 
I found this little article for management,   http://www.ipm.ucdavis.edu/PMG/r261100611.html  I also have found conflicting information about the virus.  I found literature saying it has been around for 100's of years, and I found literature saying it is new from the citrus mosaic virus from CA.  

Everything says the virus comes from a mite.  One mite, one bite infects the trees.

Here's another with a lot of simple information on figs in general http://www.crfgsandiego.org/Presentations/The%20Incredible%20Edible%20Fig.pdf

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cis4elk

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Reply with quote  #6 
Thanks for the replies and links. The nice thing about links is that there is usually something interesting, even if it wasn't what you were looking for.

Mike, the part of the soil I am referring to would be the left-over dead  bits of root left in the soil when I remove my trees in the fall. These will be left wherever I put tree every summer. The area in particular I was referring to is adjacent to the porch, a  6" layer of pine wood chip mulch that is about 4 years old.

It looks nice on the surface but a bit of digging reveals a large amount of broken down dark rich matter. The tree loved it. There are a ton of little bugs in there eating the decaying wood(a sort of millipede, wood louse, earwigs, worms....). It's rather obvious when I examine the mulch that a good percentage of bug droppings/castings are present,  I'm sure the bugs will eat the dead root bits as well.

My concern is if an insect eats a bit of dead infected root with viable virus, then it is a carrier, later that same insect feeds on actively growing root from a "clean" tree = infection.

 At some point when I have some extra time, I need to dig out my old microbiology text and see if there is any information in general about viral vitality/duration outside of a living host. I thought it was a pretty short time span, like days to a couple weeks. I was surprised by the information I found on the tobacco mosaic virus.

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Maro2Bear

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Reply with quote  #7 

Hi guys, I know this doesn't specifivally address FMV, but logically all viruses have the same basic characteristics, and one of these would be their ability to go dormant when not growing on their host.

I found ths info on the "Ask a Biologist" web site regarding the " lifespan" of a virus:

"It depends what you call life span, the definition gets murkier for things "living in some way". Usually life span refers to the average amount of time on individual organism can survive. Viruses are not complete organisms and consequently they have a life cycle in two parts: a part inside a host cell, infecting it and reproducing itself, and a part outside the cell which is closer to reproduction for higher organisms. Outside the cells the viruses have very variable life span, all finite, even in ideal conditions. Some like HIV are very short lived, some like influenza can remain infectious after longer periods. Inside the cells, the life span of the viruses kept dormant in cells can be as high as the infected cells life span. The conditions can increase this life span enormously, for example scientists were able to retrieve live virus of the 1918 Spanish flu from corpses buried in Alaska. We keep frozen stocks of virus for dozens of years. But even in these conservative conditions the life span (the infectivity in the case of viruses) is not infinite. It can be hugely variable though from virus to virus."

Last edited by Jerome Feldmann (14th May 2008 07:47:34)

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bullet08

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Reply with quote  #8 
if FMV is truly a virus, it should die once it leaves the host in short time. virus can not survive in open area for too long. however, if the virus is in some sort of dead material, it might survive longer. as long as they can be protected inside of their capsule they have better chance of survival... like inside of their dead host, they can still cause problem.

so if you are asking if FMV as virus can survive in itself, answer is not for very long. if you are asking if the FMV that's in dropped leave and/or fig can survive in the soil, answere is yes. dropped leaves and figs will rot and waste away, but the virus should be still intact inside of that host until the host is completely destroyed.

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***** all my figs have FMV/FMD, in case you're wondering. *****
***** and... i don't sell things. what little i have will be posted here in winter for first come first serve base to be shared. no, i'm not a socialist...*****
JackHNVA

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Reply with quote  #9 
If you google FMV fig pdf, you'll see papers and books dating back many decades discussing FMV. All plant refuse should be destroyed or removed from the location of other figs -  dropped leaves and twigs of affected trees

 
Attached Files
pdf pp64.pdf (766.03 KB, 23 views)


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Dieseler

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Reply with quote  #10 
In my cold zone where plants are dormant in @garage temps often in teens during January FMV is still within the plant the next season.

Some plants deal with FMV very well and grow and produce normal, violet de bordeaux is a good example in my yard as it grows normal and produces very well yet shows FMV in form of badly disfigured leaves early in season and then it wanes as season marches on.
This is one plant that saw 6-8 degree's above zero dormant in the garage some years back during a very cold spell we had.

Iv'e read its in the cells and can prevent the cells from multiplying (Elongating) like there programmed to do therfore plant being stunted but not all plants as i have seen in yard because there are different strains of FMV its been written.

Its my opinion that FMV does not get cured or leave the FIG plant because of the cold thru my experience and seeing with my own eyes.

Ischia Black (UcDavis) i had was the perfect example of not growing in 1 case with not only disfigured leaves but bad mottling of those leaves, my example probably had a nice cocktail mix of several strains of FMV.

I have seen on this forum UcDavis Ischia Black growing decent and helps me understand what i have read that FMV is slow moving in plant and perhaps a young limb that did not have the cocktail of several strains of FMV was propagated and therfore grows better such as many other fig plants with FMV.

MichaelTucson

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Reply with quote  #11 
Calvin,

A few points:
  a) There are many kinds of living material in your "soil" (including the insects you mention, plus much else), possibly including some living fig roots even if you've moved the tree. So you'd still have potential hosts present once you moved that infected tree.
  b) Even if you were able to get rid of all the living material from that area of soil, the viability (infectivity) of viruses outside of a host can be a very long time depending on conditions.  Decades or centuries in some cases, others possibly even longer, and obviously some much shorter as well.  (Maro2Bear provided one reference.  There are many that make this essential point).  There are at least 8 viruses that cause the diseases we call "FMV", and I'd be surprised if all of them have been studied for extra-host viability time span.  
  c) Sounds like there is evidence of at least some of these viruses surviving in decaying fig plant material  (post by JackHNVA).

I conclude from a and b that if you move that infected tree from that spot, you should not consider that spot "safe" from the known viruses that are present there now.

Although you're framing your questions a bit narrowly, from the context it seems that your real concern involves some symptom-free trees and a definitely-infected tree, and a desire to isolate the maybe-clean trees from exposure to the viruses in your definitely-infected tree.  Because of the likely ubiquity of vectors, I doubt you can keep the maybe-clean trees safe from infection, given that you've got a definitely infected tree nearby.  I tried (minimally) to do something like that, but seemingly failed.  (I say "seemingly" because there are so many variables here, and it's unclear whether the symptom-free trees were ever really "clean" or not).  I'm not sure what distances you have in mind to try, but if you do try then it'd be interesting to hear your observations after a year or two.

I instead have essentially "punted" on this quest of isolating symptom-free trees from the viruses -- though I still separate them to avoid gratuitous exposure, I'm instead focused on optimizing the overall health of my trees through things that I can do for them.  Good soil, good placement, etc.   That, and removing trees that seem unable to produce well or maintain overall health (whether because of these viruses or other causes).  I can empathize with the choice you face though:  you want to optimize tree placement, but have to weigh the known/perceived advantage of that particular placement, against the unknown potential disadvantage of almost-certain exposure to viruses (in that sweet growing spot where you've planted your definitely-infected tree).  I guess that's what got me to comment (empathy over the choice).  Sorry I don't have any further links, but good luck with your choice.

Mike

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cis4elk

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Reply with quote  #12 
Great replies, thanks for your thoughts, experiences, and information.
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DWD2

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Reply with quote  #13 

Cis4elk, I have not found any literature discussing FMV, or any of the other viruses that cause mottling disease in figs, persistence in soil. There are a number of studies looking at tobacco & tomato mosaic virus persistence in soil. One example is:

http://link.springer.com/article/10.1007%2Fs10661-007-0075-7

This study is pretty typical of what I have found in the literature. TMV belongs to the genus Tobamovirus. These viruses are known to persist in soil as you point out. These viruses are not transmitted by insects, fungi or nematodes, unlike the various viruses that cause FMD (fig mosaic disease). TMV and the other Tobamoviruses are easily transmitted by rub-inoculation. The FMD causing viruses appear to be only transmitted by insect vectors, certain mites. Additionally grafting or budding with an infect branch on an uninfected tree will cause transmission of FMD. A recent paper, which is attached below, indicates that 3 viruses causing FMD can not be transmitted mechanically. Before everyone gets too excited about “uninfected” trees in Turkey, please note there are some technical flaws in their testing that clearly give false negative results in terms of whether they detect virus in a tree. Mechanical transmission would be the primary reason to be concerned about viral persistence in the soil and/or vegetative material near your trees. If you have erophyid mites around, they will easily move from tree to tree well beyond usual yard dimensions. I am attaching a mite review for those interested.

 

As to the organic matter left over after pulling your trees, there is almost certainly virus in the fig tissue (roots, leaves, etc.) left in or on the ground. Transmission of FMD causing viruses by the insects and other organisms left in the ground has not been reported to my knowledge. Mites that transmit FMD viruses over-winter in the buds of dormant fig trees. It is not apparent that removing left over roots, dropped leaves, etc. serves any useful purpose. It certainly won’t hurt. If you have trees that are showing FMD and some that are not, my guess is your energy is better spent trying to eliminate/reduce any mite population you may have around when they start to reappear in April & May.

 

Dieseler, I have not seen any study demonstrating transmission through shears or other physical means. My bias is to follow the “better safe than sorry” adage on this one, but would be interested to see any publications you have seen on this issue.

 

Like Mike and many others on this forum, I have accepted that all my trees likely are infected by one or more FMD causing viruses. I am interested in approaches that give me healthier trees. Some of the members of this forum work hard to find examples of each cultivar which show few, if any, FMD symptoms. That approach requires a little more work, but it is loaded with common sense. A second approach I am trying is to look at whether a nutritional strategy can impact FMD. Also, there are molecules that activate a plant’s innate immune system. I have started looking to see if using any of those molecules can impact my trees’ health.

 
Attached Files
pdf JPhytopath_159;_181_(The_Prevalence_of_Three_Viruses_In...uthern_Turke).pdf (227.92 KB, 10 views)
pdf JARQ_38;_31_(review_-_Ecology_and_Control_of_Eriophyid_Mites).pdf (505.88 KB, 12 views)

DesertDance

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Reply with quote  #14 
I was getting pretty excited with the pending purchase of 1 1/2 acres that we might finally have the room for a compost heap.  I was planning on tossing dead leaves in there (lots of mature trees on that property), but maybe not such a good idea if the virus lives in it.  There seem to be differing opinions, as usual, and I hope separating the infected trees from the non will help, but mites can move across to other trees easily.  We get spider mites here, and as hard as we try, they come back!  Are they the mites you refer to here, or some other mite?

Suzi

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Dieseler

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Reply with quote  #15 
DesertDance its said to be the eriophyid mite, now i should have said possibly thru unsterilized shears its not proven as of yet .
But i figure and take this with a grain of salt cause im just a average gardener  that if a mite can do it by chewing into an infected plant and its been written that grafts from infected plant transmitt that cutting thru the wood in ones backyard or many infected plants and in that process coming to a clean tree with same pruners it could "possibly" do the same just like that famous mite.

Why is it just the mite what about the June bug as some call it that in some parts of the country chew on the leaves from fig plant to fig plant  ?
FMV has been studied to be in the limbs, leaves and also the fruit which i have seen firsthand in my yard and matched with pictures of studies done.

I think but not sure because CRS kicking in me as i age that Baud stated every tree is a carrier of FMV.
Also Per Sybil at Paradise Nursery, trees can be carriers without showing any symptoms.
At Paradise Nursery they at least once destroyed a bunch of trees because of the disease.

My Hardy Chicago came from there and i once thought it was disease free as i could not find any evidence on the tree then one season i notice a misshapen leaf on it Hmm i thought could this be FMV ?
Then i started looking harder season after season at this tree and realized although a very healthy looking tree otherwise there is a odd shape leaf but i have to search for such a leaf cause there were no other signs like mottling, spotting on leaf nor on fruit itself ever.
Then just last season Bada Bing !
For the first time i did an airlayer as a spare just in case off that tree cause i decided to take parent out of pot and grow inground something i have not done for many years with my fig trees.

Guess what that airlayer started growing and showed FMV thru the telltale spotting of the leaves something i never ever saw on the parent plant.

Now studies have shown that there are different strains of FMV ouch!
Personally i dont worry about FMV in my plants and learned its no big deal in most cases as i get to enjoy some the best tasting types that have it like the UcDavis Black Madeira that grows well along with some others.

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Reply with quote  #16 
Suzi, Spider mites (Tetranychus urticae) and fig mosaic mites (Aceria ficus) are different. As Ashihara et al point out in the paper I attached above, the eriphyid mites, like A. ficus, are the smallest know plant eating mites. Although it has not been examined in the fig mite/fig mosaic disease virus system, transmission of persistent viruses from one plant to another requires a very specific insect vector. So, a particular virus will ONLY be transmitted to its host plant by a specific aphid, whitefly, leafhopper, thrip, beetle, mite or etc. in every case examined to date. If you are fighting spider mites each summer, you may well be a fellow tomato grower. It is a little off-topic, but the spider mites are an example of how complex and specific these interactions are. The predatory mite Phytoseiulus persimilis is the natural enemy of T. urticae and can be used for biological control of spider mites. When a spider mite starts eating a tomato leaf, the tomato plants defense mechanisms kick-in and release volatiles, primarily monoterpenes, that attract any predatory mites around. It's a mite eat mite world you could say! I have seen no reports of predators of the fig mite unfortunately. There is a terrific review about insect vector interactions with persistent viruses here:
http://naldc.nal.usda.gov/download/19548/PDF
The bottom line for you is that I personally would not worry about composting my fig leaves and other plant waste. Assuming you have infected plants, which I think is a pretty safe assumption, and you have fig mites, you are going to get viral spread in your collection. What I want to understand better is what some of the really talented growers like Martin are doing such that their collections show little impact of the FMD virus(es) on their trees. I am about to find out for myself if UC Davis sends me the Black Madeira cuttings I requested, but it seems from a lot of posts that getting BM to grow well is a real accomplishment.

Martin, I spray my shears with 10% bleach and wipe them off between my fruit trees. I am not concerned about spread FMD causing viruses via the shears, but there are bacterial & fungal diseases that are known to be spread by contaminated shears that I am concerned about. As I said above, your "better safe than sorry" approach is a good, sensible way to protect yourself from potentially spreading ANY pathogenic microorganism, viral or otherwise.
Dieseler

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Reply with quote  #17 
DWD talented ?
Good thing i wasn't drinking my coffee when i read that.  ; )
MichaelTucson

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Reply with quote  #18 
Martin, what are you saying?  You'd do a spit-take on coffee, but not on wine or scotch?

BTW, I agree with DWD2 on the "better safe than sorry" approach when it comes to shears.  I use isopropyl alcohol.  Not because I think it's better than bleach, rather because I've got about 10,000 of those little packets of rubbing alcohol wipes left over from other purposes in the past.  So rather than waste them, I use them to wipe shears in between trees.

I do remember reading somewhere some other papers about there being multiple insects shown to be vectors for at least some of these viruses.  But I can't find the reference  (don't think I was dreaming it though).  I recall that it indicated that certain aphids transmit some of the viruses.  That also fits with observations here (not provable, but casually observed).  The mere fact that there are multiple viral diseases would suggest it's likely that there are multiple vectors.

DWD2 - I strongly suspect that optimizing overall tree health through nutrition (a good generally nutritious promix culture), good drainage / watering (same), and sunlight, play a big role in many fig trees ability to fight off the deleterious effects of these viral infections.  Though I didn't design any experiment on this, just through the serendipity of running out of different promix formulas, I've had like varieties in significantly different soils close to each other, and the observable differences suggest it.  So if you find anything about specific compounds that affect a tree's ability to fight off the negative consequences of these infections, I'm all ears (or eyes) to read whatever you report on that.  And thanks for the links above.

Mike  central NY state, zone 5

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Dieseler

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Reply with quote  #19 
MT nope just coffee i spit out laughing now the wine is saved for Sunday gravy/sauce and for washing down the Spagets and meatballs/sausage or bracioles and sometimes homemade hard crust bread or the store bought Italian bread the real hard kind not that soft mushy stuff  @ dinner. ; )
Scotch naw not much of a drinker but will drink at a social event !   ; )
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