Dave,
Fig mites only live and breed in warm zones, usually the same zones that have the fig wasps. Dusting with Food Grade DE will help to stop other chewing insects and mites if they are present, I've used it successfully, but its not a preventative against FMV. There has been many discussions about FMV in the forum archives, a search will yeild many different opinions.
Here's a discussion about FMV, http://figs4funforum.websitetoolbox.com/post?id=6035851
Quote:
The documented research has shown that FMV is not spread by seed to seedlings, but can be transmitted in as little as one (1) feeding by the fig mites. There seems to be a misunderstanding about the two (2) main vectors for spreading Fig Mosaic Virus (FMV). They are Fig Mites and Fig Growers, this is not an opinion, its documented fact. There are several universities in the USA and The Mediterranean, in commercial fig growing regions that have published papers with that statement.
Fig Mites are related to spiders and ticks. They do not cut, tear, rip or chew plant material, they insert their "mouth parts" through the plant cell membranes and suck out the plant fluids, in the process their "saliva" inoculates the plant cells with Mosaic Viruses, if they had been feeding on other infected plants. They can survive in unopened dormant buds and figs, but can only survive in temperate zones and do not "over winter".
Fig Growers graft, propagate and circulate infected plant material. They also imported fig cultivars, Capri figs and Fig wasps from the Mediterranean to improve the commercial fig industry. Due to the fact that Fig Mites can survive in figs and closed buds they have been relocated with the wasps and plant material to their new homes in these temperate zones.
This is not an indictment, just a statement of known documented facts.
I've observed that if visibly healthier limbs are propagated the young trees start out looking healthier, than when obviously diseased limbs (cuttings) are used. The other observation that I've made, IMO as stated previously, is that a lot of the FMD symptoms that are attributed to FMV are actually nutrient deficiencies and can be avoided with application of balanced fertilizers (macro and micro nutrients and better pH range).