Bulb diseases, viruses

Joe Shaw jshaw@opuntiads.com
Sun, 03 Jun 2007 21:25:03 PDT
Hi Gang,

I've been intrigued by bulb viruses since the topic came up here a few years 
back and on the IBS.  I've scoured the WWW, scientific publications and have 
written to colleages around the world to collect information about viruses 
on Crinums.

Many bulb viruses are well studied and can be devastating if allowed into a 
collection (e.g., some lily viruses).  Other viruses seem to be essentially 
unstudied, e.g., Crinum viruses.  I've found reference to Crinum viruses, 
and think I've seen virus-infected plants.  However, I have not observed 
such plants very often.  I'll try to take photos and post them online.

Additionally, Crinums that seem to have viruses are enigmantic because they 
don't decline and they don't seem to be a problem for nearby plants.  I've 
left a pot full of an apparently virused Crinum jagus var. scillifolia (I 
think that is the ID).  The plants showed wonderful mosacic symptoms. 
However, I don't have a lab to examine such things and did not actually see 
virus particles, and likewise did not do hemaglutinin or ELISA tests.

The plant grew as well as any Crinum, and flowered acceptably (but I didn't 
have a non-mosaiced plant for comparison).  I put the possibly virused plant 
next to Crinuum x herbertii and next to C. x 'Ellen Bosanquet," and then 
kept the plants in a crinum-free zone on one side of my yard.  Over two 
years neither of the bait plants developed symptoms.  Without more tests, it 
is not possible to draw conclusions about virus spread.

However, I have some hypotheses that might explain what I've observed or 
read.  Crinum viruses do exist, the known ones are rod shaped, they may be 
insect spread, and they may be spread by cutting tools (knives or shears, 
etc.).  I'm guessing that the viruses cannot be spread by leaf-to-leaf 
contact, by pollen, or via seeds.

I have tossed my apparently infected C. jagus var. scillifolia and will keep 
the two bait plants another year to see if they develop any symptoms.

If my ideas are right, Crinum viruses could enter a clone, especially one 
that is propagated vegetatively with cutting tools.  Thereafter, all 
descendent clones might be infected.  Also, if my ideas are right, sucking 
insects (maybe aphids) can transmit the virus from plant to plant as they 
withdraw sap from one plant and inject digestive juices into another plant.

If others out there have observed virus symptoms in Crinums I'd like to hear 
your experiences.

Additionally, if you have stories about viruses on other amaryllids, chime 
in, or even viruses on any bulb at all.


Conroe TX 

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