Nasty Tospovirus Killing AVs

lathyrus_odoratus(5A-IL)April 10, 2010

Two long-time hobby AV growers/hybridzers and one grower new to AVs have recently lost their entire collections because of INSV - impatiens necrotic spot virus. This virus infects over 600 plant species, including African violets and other gesneriads. These growers live across the US in varying places: west coast, east coast, Michigan.

There isn't a lot of research regarding AVs and INSV. Please follow the link below for pictures of how it devastated one grower's collection.

For more information about INSV, an article will be coming out in the next AVSA magazine written by the grower whose pictures are shown.

Regarding diagnosis:

General information:

This is what seems most important to know:

1. The virus can be "silent" in some plants, yet can be spread to other plants through thrips or propagation.

2. The virus is only spread by one insect: thrips. It is possible, but not likely because of how the virus works, to spread it to another plant through infected tools (get sap of infected plant in cutting blade and use it on another plant). If you have one silent infected plant and you get thrips, they can infect every plant you have.

3. The virus is systemic; it lives in varying concentrations in all parts of infected plants, whether there are symptoms or not. If you plant a leaf from the infected plant, all resulting plantets will have it. If you crown the plant, the new plant will have it. If you take off suckers, the resulting plantlets will all have it.

4. Monitoring for thrips with blue sticky cards is essential. As soon as you see a thrip, take fast action. Please follow the guidelines in the article above.

5. Testing is not 100% sure. There needs to be enough virus in the part you test, so a plant with a low level could be positive and test negative.

6. No one knows how long it takes symptoms to show in AVs, so isolation may not be effective (some plants display symptoms in days, others in months). Also, if you have some silent carriers, you might think they were fine.

7. Tests are available at about $5 a test. For a large collection, it would simply be less expensive to buy new plants than to test them all. Also, since the plants might test negative when they were positive, some growers feel that throwing out everything is the best thing to do.

Here is a link that might be useful: CLICK here for pictures of INVS on AVs

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Thank you so much for posting this information. It truly is important enough for the GardenWeb staff to put it into the African Violet FAQ. Actually, putting it in FAQ for all the plant forums would be appropriate since it affects hundreds of species.

    Bookmark   April 10, 2010 at 7:38AM
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Thanks for spreading the info. I'm glad the grower is writing an article for the AVSA magazine. The knowledge she's gained through her own devastating experience may save many other AVs. We now know thrips control is essential. Photographs of leaves with INSV will enable greenhouse growers, private traders, and hobby growers like me to recognize problem plants and take action to prevent spreading the virus.

    Bookmark   April 10, 2010 at 1:09PM
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irina_co(z5 CO)

I lost the whole collection a couple years ago.

African violets and sinningias are first to show infection - sinnigias in 7 days. Streptocarpus - hardest to see. Any suspicious plant - distorted leaves and discolored flowers - should be tossed. The presence of the virus in the collection can be confirmed by a local extension office - the home tests you can buy at are not that reliable - exactly as Lathyrus says.

Thrips - shouldn't be tolerated at all. There is enough infection present outside - that you do not want to risk losing the whole colecton because of one infected thrips.

All new plant should go into isolation. Usually the very young violets do not show it, when it is time to form a rosette - they start showing ring spots, grow stunted and not symmetrical. if your new isolated plant or babies coming from a leaf do not look right - dispose. A perfectly nice looking leaf can be from infected plant - and the babies will carry the infection. Virus even gets carried with seeds.

If you are working with a new plant - dip your tweezers and razor blade in alcohol to sterilize it. I keep a glass of a a rubbing alcohol on a table when I work. Once burned - always shy.

Do not try to baby stunted plants. If you do not know why it is stunted (may be it went too dry, or was not repotted for way too long - it is different story) - toss it. AVs in good conditions should thrive. If the plant is still looking bad - out with it.


    Bookmark   April 10, 2010 at 1:22PM
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Good advice Irina.

Also I'd like to say that tossing plants that havent made you happy might feel bad at the time, but is a good feeling afterwards. It also gives the rest of your plants more room to grow and more of your time to keep them healthy. ...unless you are like me and will add more plants to take their places (after isolation, of course!)

    Bookmark   April 12, 2010 at 5:05PM
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irina_co(z5 CO)

Tish - it was nice seeing you again!


    Bookmark   April 19, 2010 at 2:58PM
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trailer_gal(z4 ND)

Was looking at the recent postings and noticed two pictures that got my attention. I have been struggling with my violets for quite awhile now. Finally did get control of the broad mites but now there another problem to be concerned about.
I haven't found the INSV as yet in my violets but am watching closely, and who knows, it may be there and I don't know it.
I did spend $75 today sending away 5 samples of 5 different impatiens to be tested for the virus.
The leaves on the picture of the beautiful Yukako look suspicious to me. They seem to have discolored blotches.
Also I even think I see a ring on one leaf.
The picture posted by jwwc also looked like some of the INSV pictures I have seen.
Wondered if anyone else had noticed that about these two pictures.
Hopefully, I am just being overly concerned and both plants are ok.

    Bookmark   April 19, 2010 at 5:19PM
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irina_co(z5 CO)

Sherry -

seems like you do not live anywhere close to the County Extension office - these guys do the testing for $4-6 a shot.

You can order 5 tests from for $27. Just use the most affected piece of leaf.

Good Luck

Violets and Sinningias are the ones that show the presence of the virus in a week. Especially if you stress them.


    Bookmark   April 19, 2010 at 5:40PM
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trailer_gal(z4 ND)

I would like to try the home test. Will have more things to test, I am sure. ELISA is the test they do at the NDSU test lab in Fargo and it costs $35 for the first plant and then $10 for each additional plant that may have the same virus. I know of others that are doing the home testing, too.
I have gotten very paranoid about pests since the broad mites that I had for all those years and didn't even know what was wrong.
It is just heartbreaking when I hear of the people that have to just dump their violet collections because of the introduction of INSV. Most times people don't know which of new plants introduced the virus into their collection.
The two violet pictures that I mentioned were so pretty and yet the leaves bothered me, but, like I said, I may just be paranoid.
Thanks Irina.

    Bookmark   April 19, 2010 at 6:19PM
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irina_co(z5 CO)

Sherry -

for me the most obvious feature was the mottling on the leaves. If you look at the pics that Lathyrus gave us a link to in a very first post - it is a pic 1608 with "Galiwinku". The second - the flowers do not look right, the shape becomes asymmetric, the color - washed and mottled.

I would say that your Fargo guys are not cheap and I would purchase ELISA strips from for the fraction of the cost.

But if one(1) test comes positive - you need just to start throwing away everything. You can get leaves from your club friends, from us - and rebuild everything in months. Otherwise you will be sitting on a time bomb - you wouldn't know if one of your good looking plants from previous generation carries the hidden infection. We talked with Pat Hancock - the Buckeye hybridizer - about INSV - and she said that 25 years ago a lot of people lost their collections and she has a whole album of photos how it looks like. And sometimes the perfectly healthy looking plants tested positive. So - they just were waiting for thrips to come - and start spreading the infection.

Good Luck


    Bookmark   April 19, 2010 at 6:57PM
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trailer_gal(z4 ND)

If you look at the Yukako, 2nd picture, on the bottom to the left there is a stem with two flowers hanging down. One flower is touching a leaf. In the center of that leaf, taking up about 1/3 of the leaf, I can see a circle. On other leaves I can see brown discoloration both on tops and undersides. Do you see any of these or is it just me and my computer?
On the violet posted by jwwc, 3rd shows discolored flower. 4th picture the baby leaves look odd.
Ok, I am going to quit now before I drive everyone crazy, including myself.

    Bookmark   April 19, 2010 at 7:55PM
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GrowHappy(z7 MD)

Irina, I've read that Episcias also show the virus pretty quickly. If the symptoms can be revealed in Violets and Sinns within a week, is it faster for Episcias?


    Bookmark   April 23, 2010 at 7:54PM
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Growhappy, I've been reading accounts from several people who have had plants test positive. Based on their experiences (and Irina's) AVs can show symptoms quickly, can take many months to show, or may not show symptoms at all. One plant that tested positive had no symptoms until 9 months after the person had completely cleared a thrips infestation. Others, as Irina noted, have tested plants that showed no symptoms at all, yet the test was positive. As far as I've been able to tell, no one has studied AVs related to INSV so no one knows the specifics of it related to time frame, etc.

Sandy, who wrote the recent AV Magazine article about INSV, said that she found changing light and temperature was how she originally found she had a problem. She changed lighting and temperature because she thought it might account for the symptoms she had. Within a week or so of doing that, her plants became much more symptomatic.

I found an article that echoed that changing light and temperature sometimes will work to accelerate development of the virus. Sandy suggested that if anyone has a plant about which they are concerned that they should increase the temperature and light.

Also, as noted, Epicias can succumb very quickly. There are other "indicator" plants. According to a Colorado Extension article, "Early warning of virus presence also can be noted by using indicator plants or plants that show TSWV/INSV symptoms earlier than others. Such plants include the petunia cultivar 'Calypso' and gloxinias. Both plants are extremely susceptible to both viruses and will show symptoms within a week after infection. Non-sticky blue or yellow cards placed near indicator plants can attract thrips and increase the likelihood that the indicator plants will become infested." See link below for entire article.

A Univeristy of Mass article also suggested using an indicator plant. "The petunia cultivars Calypso, Super Blue Magic and Summer Madness have been shown to make good indicator plants for several reasons. First, these varieties are highly attractive to western flower thrips. Secondly, infected petunia plants do not serve as source of virus in the greenhouse because INSV does not become systemic within these petunias. Infected leaves can be picked off and discarded and petunia indicator plants can remain in the greenhouse to continue monitoring. Another reason is that the virus lesions show up very soon after thrips feed. Thrips feeding injury on the foliage leave distinct white feeding scars. If the thrips are carrying INSV, a brown rim and, later, a circular lesion can be seen around the white feeding scars as early as 2-3 days after exposure to thrips."

Here is a link that might be useful: Colorado Extension Article

    Bookmark   April 26, 2010 at 2:17AM
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