Virus transmission in Amaryllid seeds?

Tony Avent
Fri, 11 Sep 2009 14:33:54 PDT

Great points....cannas are a plant in which one of the viruses that 
affect them can be seed transmitted.  When we first tested cannas over a 
decade ago, some had as many as four different viruses. One by one, we 
are finally getting most of them cleaned of virus. wrote:
> On 10 Sep 2009, at 21:55, Tony Avent wrote:
>> unless the virus causes a significant problem such as disfigurement of vigor
>> loss, most folks never suspect a problem.  It's only the plants that show
>> symptoms that cause gardeners to get upset. 
> The real issue isn't infection with this or that virus in particular, but the 
> gradual infection of a plant by a number of viruses. Individually, none of them 
> would amount to much of a problem, but as the virus titer goes up (i e when a 
> plant is progressively infected with an more and more viruses), vigor declines. 
> This is the usual explanation why old cultivars propagated by vegetative means 
> ultimately disappear or become so fussy to grow that only a few enthusiasts can 
> give them the attention they require to stay alive.
> Tissue culture methods have been used to clean up a surprising range of plants, 
> ranging from show auriculas on the verge of extinction to Cosmos 
> atrosanguineus, formerly a very rare plant, today sold widely in 4" pots.
> But there's an even more insidious problem: those vigorous plants that tolerate 
> viral infections and then act as typhoid Marys, infecting other nearby plants 
> via transmission by aphids, leafhoppers, and uncleaned garden implements.
> There are some mysteries in the world of commercial bulb production. The little 
> narcissus 'Tete a Tete' is entirely virused, yet sold very, very widely. You 
> would think that someone would put it through tissue culture to rid it of its 
> virus(es), but evidently it has sufficient vigor as is that the producers can't 
> be bothered.
> Another mystery is the horribly virused form of Crocus kotschyanus that is 
> sold. Its flowers are so deformed that it has no garden value at all, yet this 
> crocus is quite easy from seed, and seedlings reveal its true beauty. I always 
> thought of it as a rather small-flowered crocus until I obtained some seedlings 
> from a naturalized patch of it that has spread by seed.
> If all you are growing is common garden plants, the issue of viral infection 
> can be ignored, but if you are growing species grown from seed, you must be 
> much more careful. One rule of wisdom applies to lily growers: if you wish to 
> grow the species from seed, then you must not grow any of the hybrids in the 
> Dutch bulb trade because they are one and all virused and will infect and 
> destroy the less robust species.
> As for transmission by seed, I believe there are a few plants where this 
> happens, but for the life of me cannot recall which genus.

Tony Avent
Plant Delights Nursery @
Juniper Level Botanic Garden
9241 Sauls Road
Raleigh, North Carolina  27603  USA
Minimum Winter Temps 0-5 F
Maximum Summer Temps 95-105F
USDA Hardiness Zone 7b
phone 919 772-4794
fax  919 772-4752
"I consider every plant hardy until I have killed it least three times" - Avent

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