Virus in bulbs

David Fenwick
Mon, 03 Mar 2003 08:11:49 PST
>>>>>There is a lot of virused material in the trade and
several nurseries have a few cultivars of Crocosmia that are terribly
virused. Any comments Dave? In my opinion it was viruses who wiped out all
those fabulous Crocosmias you mentioned of late.

Dave here,
Yes, Alberto I'd like to raise a few points.

I hate to contradict you but I sincerely doubt viruses were responsible for
wiping out many of the old Crocosmias, bad winters and Adolf Hitler were
primarily the two main causes; but I am considering 'disease' also and for
reasons I will discuss.

It my opinion that the commercial popularity of a genus, any genus, and its
sale, has a direct relationship between the spread and increase of pest
populations and disease. Hence the more people that grow Crocosmia, the
higher the level of disease and increase in pests, many of which will be
virus vectors. Given that when plants are propagated, pests can be too, and
transfered as unseen eggs, instars or larvae, and fungi, bacteria and
viruses transmitted unseen systemically.

In my case, as a national collection holder it is very important for me to
continually seek healthy stock, or know where I can get it from, and mainly
because any collection of this size and of same genus can be considered a
monocrop. In some respects monocrops are much easier to look after and
manage, however, pests which translocate viruses have a devastating
potential, and thus the correct proceedures need to be taken regarding pest
and disease management, and crops need to be continuously supervised.

Having followed Crocosmia hybrid development very closely from the breeding
of Crocosmia x crocosmiiflora in 1879 it is possible to see a pattern emerge
in the development of hybrids, their fashion trends and decline. However
this pattern is greatly masked by both the first and second world wars, but
I am certainly looking into the fact that the higher the sale and fashion,
the quicker the decline and probable extinction, but this is difficult when
you have to consider two world wars. It is more probable though that plants
have suffered because of changes in the economy, garden ownership, harsh
winters, and lack of time before and between wars to release these hybrids

This commercial frequency, the dates plants were sold, from specific
nurseries, eg. such as with Lemoine, France, can be recorded in his
catalogues from 1879 - 1908, and may give an indication of resistance to
pests and disease, and thus eventual hardiness, if combined with evidence on
parentage for that hybrid. This data could also be used as an aid to
identify un-named forms, as graphs can easily be prepared and the evidence

Getting back to viruses. It is obvious for in general, if we can't cure the
plants, we must kill them. However there is a case whereby we are condemning
plants to possibly extinction by killing them. Alberto mentions national
collections and specifically, the Canna collection. To answer this, one must
firstly consider the plants importance, its rarity, its place within the
garden, potential vectors of viruses in the local vacinity, the management
of these vectors, and the risk of spread to other plants by mechanical means
(by human or leaf contact), and of course correct quaranteen proceedures
when plants enter collections of this type. But please don't condemn me for
my honesty when I believe there is a case for conserving plants with virus,
and yes there is a very good case for this to be done.

We have to look at the types of viruses that our plants may have, their
symptoms, the vectors in each specific case, their ease of tramsmittion, and
how virulent the viruses are. It is very important that when talking about
conservation issues and viruses, that we do not generalise, as each case is
important, and each case must be considered by scientific determination.

I have only ever had one really badly infected virused Crocosmia ever sent
to me, and this was destroyed. In conserving old hybrids it is obviously
highly probable that many plants contain viruses that can be considered
latent, have little or no effect on plant growth, and low risk of spread. It
is threfore for us as an organisation dedicated to bulbs both to educate,
neccessitate, facilitate and promote further scientific study in this area,
and in our own countries.

It is also possible that through micropropagation, and by post
micropropagation selection, we may eventually be able to distribute
certified virus free stocks.

Best Wishes,


David Fenwick
NCCPG National Collection of Crocosmia with Chasmanthe and Tulbaghia
The African Garden
96 Wasdale Gardens

----- Original Message -----
From: "Alberto Castillo" <>
To: <>
Sent: Monday, March 03, 2003 2:22 PM
Subject: [pbs] Virus in bulbs

> Dear Mary Sue:
>                           You are wrong: not all panic at viruses. You can
> still see remarks like "well, it has virus but I like it anyway" too
> Fortunately there is a growing concern and you have growers like Diana,
> Wallace and Dash Geoghegan that spend lots of time and money in taking
> precaution to sell healthy material.  With time (and no doubt with more
> valuable collections destroyed by viruses) people will learn that it is a
> poor bargain to keep a diseased incurable plant against the rest of the
> collection. We did not invent virus: it is a terrible occurrence that we
> encounter during our experience as bulb growers. Right now, before our
> noses, one of the most fantastic projects of our time, the assembling of a
> huge Canna collection has been put to an end by this. Most of you know
> the National Collections scheme in England. Well, there was a fabulous
> collection of them being assembled and the owner was very happy to have
> found in France 52 cultivars most of which would prove new introductions
> the 140 others he was already growing). BUT, in came the Trojan horse!
> those plants from France some had a virus that rapidly spread to other so
> far healthy ones. That virus was masked by the plants' inherent vigor.
> the owner noticed  the appearance of uncommon yellow mottling in many
> had them tested and it gave bean yellow  mosaic and Canna viruses. As  a
> result 70 cultivars (yes, 70!) had to be destroyed at once and the news
> that he had discontinued the project altogether. So remember this short
> every time something shows symptoms and you decide to keep it. In my
> experience in most cases this is a common plant that sooner or later you
> could replace!
> One can never overemphasize the need of a quarantine period . Do maintain
> your newly introduced plants away from your collection for a time (two
> at last). Virus symptoms can be masked (there are symptomless and latent
> viruses) but under periods of serious stress (like when you take a plant
> from its "home" and take it somewhere else) symptoms can appear. They are
> more visible (at times ONLY visible) in new growth so watch for the tips
> new leaves. If they are uniformly green you have many chances that the
> is healthy. If it shows mottling in a different shade of green be very
> worried. If you are not convinced do not let it close to your healthy
> collection. For instance if you live in Halifax, send it to Vancouver for
> safety!.
>                        You are right in that there is so little in the web
> on virus symptoms images. In the Ball Guides there are a few images of
> viruses in Liliums, Agapanthus, Canna and in  a number of dicots.
>                         There is a lot of virused material in the trade
> several nurseries have a few cultivars of Crocosmia that are terribly
> virused. Any comments Dave? In my opinion it was viruses who wiped out all
> those fabulous Crocosmias you mentioned of late.
> Regards
> Alberto
> _________________________________________________________________
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