Scottish Rock Garden Club Forum
Cultivation => Cultivation Problems => Topic started by: pehe on September 20, 2010, 11:38:53 AM
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In another virus thread Lesley Cox suggested a virus database. I think that would be a great help to us newbies.
Here is my contribution:
In spring I was sad as I realized that most of my Nerine bowdenii pots was virused. To avoid further spreading of the virus to my Sternbergias and other Amaryllidaceae I discarded them. The healthy looking Nerines was isolated and treated with a systemic insecticide several times during the summer. The rest of my bulb collection was treated too to avoid any aphids.
That was a good precaution because now Nerine sarniensis show clear signs of virus. I will discard it as soon as possible and I consider to get rid of the rest of the Nerines even if they look healthy now.
Can any one identify the virus and do you know which plants could be infected?
Poul
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Poul - I know nothing about Nerines but Sternbergias will grow, flower well & increase when virused. I'll post a picture of one in the next couple of days.
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Poul, it is usually very difficult to know exactly which virus (or virusses) you are dealing with just by looking at the visible symptoms. There is a Nerine Latent Virus that also occurs in nature but if this is it or if it is the only virus that has infected it can only become clear if a leaf sample is lab tested through Das-Elisa tests. Which is expensive and generally only worthwhile in case of doubt. If it is already obvious it is infected it wouldn't make a difference anyway and testing would be a waste of money. According to the Pacific Bulb Society website Nerine Latent Virus infects members of the following families: Amaryllidaceae, Amaranthaceae, Chenopodiaceae & Solanaceae. Although no pictures of the symptoms, the site provides some info: http://www.pacificbulbsociety.org/pbswiki/index.php/Virus
Certainly in bigger collections of a single genus of plantfamily it is vital to be on top of any sucking insect. I used to be very much in favour of using natural predators to combat aphids and other virus vectors but they just don't act fast enough so I spray because I don't want to run the risk of endangering my research collection. Be aware that many viruses in bulbous plants are also spread by nematodes so insecticides are not always enough.
Edit: to give some idea, in the Netherlands testing a sample usually costs between 6-10 euro per sample depending on the possible viruses it needs to be tested on. Each year I have about 6-8 samples from my Arisaema collection tested (which can suffer from poty and mosaic virus). Luckily the last 2 years no positive tests (or negative, just how you look at it....) but that is no quarantee my collection is virus-free because plants can be carrier but not show it unless under stress so I am constantly on the alert for any symptoms, both in my existing collection as well as new additions which are always grown separate from the rest for the first year.
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Pascal,
Thank you for the information and the very usefull link.
Poul
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This is the virused Sternbergia which I mentioned above.
These plants derive from one bulb obtained 14 years ago from Monocot Nursery (as S. lutea angustifolia). I think it was probably infected when I received it but it has, nevertheless, increased steadily & flowers every year. The infection is obvious in the leaves (I have boosted the contrast slightly) but also shows as lighter patches in the flower as it ages - not easy to photograph.
I keep this pot well away from other plants.
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In another virus thread Lesley Cox suggested a virus database.
Did I? ??? Not that it's not a good idea.
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Lesley,
You are foregiven! You come with that many great ideas, so it could be hard to remember all.
Look here: http://www.srgc.org.uk/smf/index.php?topic=5477.0
Poul
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Oh well, that was back in May, another life almost. Remember, at my age time goes by VERY QUICKLY! ::)
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Virus in Crocus banaticus >:(
Poul
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Poul, is this a seedling that's infected?
Unfortunately I found similar colour-breaks among a batch of C. pulchellus seedlings now flowering for the first time. Although it's likely to be due to infection of the seedling (despite precautions to control aphids etc.), I don't think that the possibility of transmission by seed can be ruled out completely :-\
Does anyone know of controlled experiments done with Crocus or other Iridaceae?
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Ashley, yes it is a 5 year old seedling, and it is the only one of about 30 seedlings, that is infected (or I think is infected, I am not sure. As a precaution these 3 corm are binned). None of the parrents are infected, so I don't think the virus is seed borne.
Poul
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Oh well, that was back in May, another life almost. Remember, at my age time goes by VERY QUICKLY! ::)
HEAR HEAR Me too ;D ;D ;D
Göte
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"Does anyone know of controlled experiments done with Crocus or other Iridaceae?"
Not exactly a "controlled experiment" or even with Iridaceae, but I have noticed, or can only account for the spread of virus via soil or the water draining from a pot of virus-infected plants.
I am neurotic about virus infections and vowed never to accept plants from certain people - I let my guard down once and accepted a pot of very rare bulbs from a virussed collection. In no time at all seedling Lachenalias (Hyacinthaceae) growing nearby, and in reach of water draining from the suspect bulbs, showed signs of a severe virus infection. I don't think there were any insect vectors in action as I spray my bulb collection regularly to keep them off.
Anyway, Lachenalias are a good "test" bulb as they grow easily and rapidly from seed and distort spectacularly when infected by certain viruses - plant a few with the suspect plants and wait and see...
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Rogan, what a scary story. I didn't know virus could spread via draining water. A very good argument to get rid of a virused plant immediately!
Poul
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Nematodes are also known vectors for some viruses so it could be they have escaped with waterings to nearby pots.