Unfortunately,
at present it is difficult to state which viruses are the most serious
because to do so requires observation of many dahlia cultivars infected
with specific virus isolates. However, at present we have only a
few virus free plants to work with. It will take time to free material
of virus and propagate sufficient material for testing of virus
isolates against specific dahlia clones. Also, the question is difficult
to answer because there are virus isolates that do not appear to
be causing significant damage. However symptomless virus isolates
are a problem because they may not be symptomless on all dahlia
cultivars. The virus is just waiting for a chance to infect some
new introduction to the garden. It is also possible that some viruses
may affect plant and blossoms in some valued way.
