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Subject: Does FMV affect all parts of a tree, roots, all branches? Replies: 35
Posted By: FrankieC Views: 536
 
Quote:
Originally Posted by hoosierbanana

It was first observed less than 100 years ago, and was most likely much less common then than it is today. Like Ray and many, many, other people have said, virus symptoms are virtually non-existent on trees found growing on the east coast.



Many people have expressed frustration about the mite being established in CA and say there is no point in making any effort, while it has not stopped others (although not all of them have made public statements) from successfully protecting the health of their collections my monitoring and treating for fig bud mites. If you plant a seedling and be careful to not introduce the fig bud mite from materials you get from another collection, you will never see any FMV symptoms on them in WV, or any other region isolated from wild fig trees for that matter. Fig bud mites are host specific, they cannot reproduce on other species.

Could you provide a reference please, I've read several surveys and the highest infection rate was found in CA, but then again they only managed to find and test symptomatic trees. Before you say "all tree in CA have symptoms" please know that you would be contradicting observations made by several CA growers. Alma is immune, it is only logical that some other varieties are as well. 

 And the seedlings you mentioned? TC plants that have been virus indexed? undergone thermotherapy? The ones discovered to be free from virus in many surveys using pcr analysis around the world? Alma, Hamma? Even without expensive testing there is a clear difference between symptomatic and non-symptomatic trees, there is no in for a penny in for a pound here. The symptoms have been found to be directly correlated with amount of virus present in the plant cells, the particles need to be so numerous that they begin to actually gum up the works of the cells in order to cause any symptoms. The more virus, the more severe the symptoms. FMV has been shown to not be transmissible by sap, and can only migrate through the plant between adjacent cells, but the fig bud mite not only transmits virus from plant to plant it also rapidly increases the spread of virus in any one plant. Because virus replication and cell division are not tied together the amount of initial virus in a newly divided cell can increase or decrease. Rapid cell division relative to virus replication reduces the viral load, this is the reason thermotherapy works, the virus is denatured by heat and unable to replicate so each cell division cuts the number of viruses in half until none remain and virus free material is collected from the new growth.



 I spent a whole season battling "rust" and "nutrient deficiency" only to discover the symptoms were from fig bud mites which spread persitent virus symptoms to about half of my collection (mostly trees that previously showed no symptoms, or at least got worse). It did give me the opportunity to do some things that people said was previously impossible, such as comparing symptomatic vs. non-symptomatic trees of a couple varieties. 

The impacts can be much worse than cosmetic, growth can be stunted, fruit can have necrotic spots and drop.
My big question is...is FMV/FMD really a problem?

Absolutely, figs are not an economically important crop in the US so receive very little research. But in areas of the world where they are more important there are efforts to preserve healthy specimens. 

Please remember that the advent of the internet and globalization has rapidly increased distribution of all types plant material and pests, we can look at the past but nobody knows what the future holds. Also consider that a disease which spreads from one tree to another does not take modern science to fight, people have been destroying sickly plants for thousands of years.


You are assuming nurseries that supply commercial orchards have the same attitude about FMV as you do. But they are more likely to undertake sanitary selections and or have mother trees tissue cultured to avoid the liability, the costs would be minimal compared to the risk of having large orders sent back. After all, best practices dictate that symptomatic plants should not be propagated from, if it were not possible then why would that standard be set for commercial growers?

DWD2- In the past you incorrectly diagnosed fig bud mite symptoms as virus symptoms. Hopefully you can see how it is impossible to interpret virus symptoms effectively without distinguishing between other similar symptoms. 
https://figs4funforum.websitetoolbox.com/post/instant-fmv-6004031



The version of Black Madeira that has highest demand currently is from KK, which has no obvious symptoms, I also grew a symptom free BM from a mother plant directly from Wolfskill. I've also propagated symptom free versions of a half dozen others from Wolfskill, though I have discarded most (including BM) for poor suitability to my climate.



Please see my comments above, as well as the threads where I describe my experience with fig bud mites, you will find them with a simple search. You are right to think that after a season or 2 all plants in a collection would most likely be infected, but there are also factors such as natural predators which will limit mite populations in some cases, so every infestation will vary. I discarded almost a whole year's worth of new plants, sure they were still alive but severely stunted and a pale comparison to their mothers, new plants from the healthy mothers quickly outgrew them. In the long run it was the right decision.

That year I planted a small orchard, which was infested at the time of planting and was in close proximity to symptomatic plants. Most of those plants showed symptoms but only a small number needed to be replaced, however, because the bases of the plants are still heavily infected; pruning back can cause symptoms to flair up and I I had to replace another tree this year from that group which froze back and only managed to produce sickly and stunted growths from the crown this spring. There was stark difference in growth and production between many symptomatic and non-symptomatic plants of the same variety, and no improvement in flavor. The symptoms really do vary from tree to tree, and it causes inconsistency from plant to plant. For a group like we have here, which often discusses and evaluates varieties, this extra variable is quite undesirable.

I am not professionally trained, although I do have a strong interest and respect for science. Who I am is someone who has been affected negatively by interacting with the fig community, as many other people and nurseries seem to be also. I did my best to provide supporting evidence, because I knew there would be resistance, but it is dismaying to see my experience ignored. Ray is right to worry that as a community we are acting recklessly, I've prevented multiple heirloom/family/otherwise symptom free trees owned by new members from being affected by material with fig bud mites, though it has brought me grief and pushed me out of the popular crowd. So regardless of whether you or others take me seriously I will continue to inform people, I know I would have appreciated someone diagnosing fig bud mite symptoms on my plants before so much damage was done, and although it puts those people in an awkward position to choose who to believe, most have been appreciative.

I've spent many hours reading research papers and observations from members of the community, as well as carefully watching my own trees. If you would like to discuss any of what I've written I'd be happy to, assuming you remain intellectually honest and open to additional evidence.

 

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