Pleiones -- Paul Cumbleton's hybrids

[sjusovare]

John, too much nitrogen allows the symptoms to be visible because the plants have a more active metabolism, however even if the symptoms recede with lower quantity of nitrogen, the virus is still present and can contaminate other plants (even in a latent stage), which is why I said that factors such as nutrition doesnt really have effect on the overall presence of virus or not, at most it just makes their presence visible, but is not directly responsible of their prevalence in collection (there I think that hygiene practices and avoidance of transmission factors such as mites and aphids are more important)

As I said in another pleione group, I think the main reason why we see so many plants with virus nowadays is not that they have become more common, but simply that those have been around for years in seemingly healthy plants and are just now starting to show because the plants are stressed by unusual weather patterns.

Taking that into account, the only way to be sure to have a healthy collection would be to systematically EM test every plant and discard all those showing up positive, but it is unfortunately much too costly, and even industrial producers could not afford that (the example of the phalaenopsis industry comes to mind, they clone plants by the millions, a big % of which are carrier of viruses in a latent stage but they can't afford to test all their mother plants. When questionned about the virus problem, their answer is always that "we have to accept some level of virus presence, systematic testing would result in producing plants too costly to be affordable by most of people").

Considering the prevalence of viruses, the fact they can have multiple hosts (one of my pleione showed mozaic symptoms after have spent time in the cucumber greenhouse, might be a coincidence but...) and that they are unbiquitous in the environment, even having proven uncontaminated stocks doesnt preclude they will remain so. With all that in mind, perhaps we indeed have to accept that there will always be virus present, and we should search a way to keep them from expressing rather than trying at all cost to avoid them which seems a lost fight.

[johnw]

Julien - Agree fully with what you say.  The only Nerines we've seen that exhibit virus in the form of mis-shapen flowers and which do not respond to nitrogen witholding in any way are 'Miss  Frances Clark' and 'Mother of Pearl'.  One wonders if their pollen is infected.

john

[monocotman]

Another reason for virus to be prevalent is that the main form of propagation is vegetative.
Many of the plants sold are individual clones.
Once a plant is infected there is plenty of opportunity for it to be passed round to other growers.
They never go through a 'clean up' phase through seed propagation.
We have seen this in other species - cannas come to mind,

Regards,

David

[sjusovare]

That doesnt really explain why whole collections get infected in really few time, and why even plants bought from professional suppliers which were raised as seedlings are also concerned.
I agree, an infected plant can be propagated and passed around, but I think the problem is deeper than that since it's not only one specific clone (though Zeus Weinstein is known to be highly virosed) but I've seen in lots of different plants, no matter the supplier.
By the way, there is no such thing as a "clean up" through seeds, despite the common assumption, seeds are not virus free, some virus are kept out, but others like the common potyvirus does infect the seeds as well (and even the meristem), and producing seeds is also in itself a risk to contaminate the mother plant via the pollen of the the other, especially since there is no way to know which plant is infected before it shows symptoms.

[Paul Cumbleton]

Though I said I'm stopping growing Peiones, I will be retaining just a very few and many of these will be the autumn/winter flowering types. These have been grown separately from the rest of the collection for much of their lives and as yet have never shown any virus symptoms. I have shown photos before of Pleione Marmoset, one of my autumn/winter flowering hybrids (a cross between P. maculata and P. Piton). One bulb in the pan of mixed seedlings of these is flowering for the first time and has turned out to be especially good. The flowers are are about half as large again as the other clones that have flowered, and it has a large open lip and broad petals compared to them. Picture below.

Paul

[odvdveer]

That is beautifull
I didn't know there were autumn flowering pleiones

[Luc Gilgemyn]

Though I said I'm stopping growing Peiones, I will be retaining just a very few and many of these will be the autumn/winter flowering types. These have been grown separately from the rest of the collection for much of their lives and as yet have never shown any virus symptoms. I have shown photos before of Pleione Marmoset, one of my autumn/winter flowering hybrids (a cross between P. maculata and P. Piton). One bulb in the pan of mixed seedlings of these is flowering for the first time and has turned out to be especially good. The flowers are are about half as large again as the other clones that have flowered, and it has a large open lip and broad petals compared to them. Picture below.

Paul

That IS an excellent flower Paul !