Scottish Rock Garden Club Forum
Cultivation => Cultivation Problems => Topic started by: annew on February 07, 2010, 08:58:39 PM
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I know Martin had something to say about 'stag', but in the hope that it isn't as bad as he stated, I've been googling for ages trying to find other people's experiences and largely drawing a blank. The RHS website is useless for this. To this end, can we use a bit of Forum Power and ask anyone with any experience of stag infection/ control or otherwise, preferably with photos, to please post here. I hope this way we can have a central information point for reference. Thank you!
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Here are somepictures from an earlier thread.
I will search for othr references in the Forum and copy them here if they are pertinent.
Re: Galanthus mid February to March 2007 Mark Smyth
« Reply #18 on: February 20, 2007, 08:21:55 PM »
Stagonora curtisii is a fungal infection. Symptoms are leaves, sheaths and bulbs with red streaks and spots. Leaves usually have a kink where the infection is/was. Flowers can abort in the spathe and turn grey. Two of the best collections were recently nearly wiped out.
Early stages are simply small amounts of rusty streaking on the bulb or kinked leaves
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My photos from a couple of years ago
Thankfully I've only seen it in one bulb so far. I think from now on I'll dispose of affected bulbs rather than treat. If only the hard frosts this year would have killed it off
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This is a handy link, mentioned before, from the PBS:
http://www.pacificbulbsociety.org/pbswiki/index.php/Stagonospora%20curtisii
Other talk of treatment, mostly with chemicals not available to the amateur gardener, in this thread:
http://www.srgc.org.uk/smf/index.php?topic=2871.0
.....some posts from there and other threads are repeated in the next post....
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Some posts gathered from elsewhere:
Alan B:
I am having a hard time figuring out what Stagonospora actually DOES?
Okay, the leaves look a bit manky so presumably there is less good leaf left to photosynthesise and the bulbs do not bulk up so well. Therfore I can see that it might cause snowdrops to diminish over several seasons. However, in the account by Matt Bishop in the Daffodils Yearbook, it seems that the disease spread to and killed many of his bulbs between the end of the snowdrop season and June of that same year when he dug them up. Apparantly the bulbs had rotted.
I cannot work out how die-back in leaves relates to rot in bulbs. If you dig up a snowdrop where the leaves show signs of stagonospora will you inveviatbly find that the bulb is rotting? Which comes first?
Mark S
Just now you may see red stains and streaks on the bulbs as you see on Hippeastrums.
Martin B :
Alan,the fungus infects the whole plant, leaves, flowers and bulb. The symptoms first show on the leaves, but it's not simply a case of the leaves alone being affected - at the same time the fungus is at work in the bulb, destroying areas of the bulb scales, just as it destroys areas of the leaves. So it's not simply a case of damaged leaves reducing the snowdrop's ability to photosynthesise. The whole plant is being necrotised.
The first year that the disease shows is when the leaf symptoms appear (concurrent with some bulb damage - showing as reddish staining and rotting of outer scales) followed in the second year by worse leaf symptoms, flowers also turning brown and/ or failing to emerge from the spathe, further bulb scale rotting, and third year usually total bulb death (or almost total, with no leaf growth). Sometimes it can be faster, especially in very wet soil or a very wet summer, as in Matt's case.
Maggi:
The stagonospora curtisii fungus spores are carried in the air, too, so physical removal of affected plants is not necessarily a permanent cure
Robsorchids:
oh so thats what that red colouring was on my hippeastrums! seems quite common on dry bulbs?
Alan B:
This paints a very gloomy picture should my snowdrops ever succumb to Stagonospora, particularly as I have no access to Carbendazim without trying to pass myself off as a nurseryman! What stops "wild" populations of snowdrops being decimated by a disease like this? Or does some small percentage of snowdrops have a natural immunity, thereby enabling a wild population to regenerate over a period of time?
Mark S:
I think the problem is the swapping and buying that goes on. You don’t know who the suppliers are buying from. In a stable wild population I guess those that get it die and that's it. Also in the wild you don’t see the clumps that grow in gardens.
Art:
Is there nothing available to reliably deal with 'stag'? Should we just dispose of any bulbs that are affected?
This info would be welcome in case I find it.
MartinB:
Carbendazim, for those who can get hold of it, is the best fungicide for stag, and good for most bulb ailments. It replaced that old standby benlate and was sold most recently to gardeners (before the EU review) as Spotless Fungicide. It can still be obtained if you're a nurseryman, greenkeeper etc. from the kinds of suppliers they deal with, but isn't on sale in garden centres any more.
I don't know of any other fungicide available to gardeners that works on stag. The usual advice is to try any wide-spectrum fungicide you can buy in the garden centre and hope it has some effect.
Paddy:
I wonder if carbendazim is present in any of the chemicals available to farmers for crop spraying?
Or, are any of the agricultural sprays effective in the treatment of fungal infection in bulbs?
MartinB:
here's a link to a goverment website listing agricultural fungicides containing carbendazim. It's used on many crops, including for dipping apples yet gardeners can;t be trusted with it!
http://www.pesticides.gov.uk/applicant_advice.asp?id=860
This website only shows uses for dipping fruit, but these products have many other crops spraying uses. Bavistin, at the top of the list, is the one most commonly available.
Hans J:
We have here in Germany only two products with Carbendazim :
Aagrano UW 2000
Harvesan
both contain Carbendazim -but are only available for farmers- not for private gardeners
Benomy ( Benlate ) has not been available for a long time.
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Well done, Maggi :D
Given the info so far, has anyone tried these various treatments who can report back on results?
Occasionally, I get bulbs coming through with small brown tips. Is this stag? I usually pinch them off as soon as seen, which seems to solve the problem.
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For the first time ever I seem to have Stagonospora infection on some dwarf narcissi. I have a small amount of very old Carbendazim (as 'Bio Supercarb') which I will try. Since it is in sealed packets I presume it will be OK. I will report the results, if any. Is copper fungicide of any use?
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Gerry, Zineb is very effective although not a systemic. Meaning you have to use it regularly before and after the "normal" period in which Stagonospora symptoms are seen.
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Anne - only just noticed your post.
This subject came up on the 'Galanthus Winter 2009/2010' thread a week or two back.
Here is what I posted then "The RHS Daffodil, Snowdrop and Tulip Yearbook 2009-2010 contains a very authoritative article on the subject of fungicides, written by Gordon Hanks, entitled 'Fungicides for amateur daffodil growers'.
He goes into the current legislation, where to get the most up to date information on approved pesticides and a review of all fungicides available for amateur use on ornamental plants.
The thing to bear in mind with these chemicals is that most, if not all, of them are preventative rather than curative and that they work by creating a barrier which stops the plant from being infected. It follows therefore that if your plant is already infected then drenching it with fungicide is, in itself unlikely to save your plant - it is necessary to cut out all of the infection first, before drenching it in fungicide (the fungicide then acts as a barrier to help what is left of your plant from becoming re-infected).
Don't forget also that the spores of stagnospora curtisii are believed to survive in the soil for as much as 5 or 6 years, so when you remove the infected plant, you also need to remove the immediate soil and plant a non bulbous plant, from a different genus, in its place (I wrote an article for the 2008-2009 RHS Daffodil, Snowdrop and Tulip Yearbook, entitled 'Collecting Snowdrops - Some Observations', which goes into a lot more detail about what needs to be done)." [the latter article covers both immediate & after treatment]
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Chris refers to some photos and comments made in that that thread 'Galanthus Winter 2009/2010': pages 28-30
http://www.srgc.org.uk/smf/index.php?topic=4674.msg132711#msg132711
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Gerry, Zineb is very effective although not a systemic. Meaning you have to use it regularly before and after the "normal" period in which Stagonospora symptoms are seen.
Alberto - I don't think Zineb is available in the UK, at least for amateurs. A quick internet search suggests that Dithane (Mancozeb), though not identical, is chemically related. Maybe worth trying.
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Here is an extract of an article by Chris Sanham.........
(The article, from which this extract is taken – ‘Collecting Snowdrops – Some Observations’ by Chris Sanham - was originally published in the 2008-2009 Edition of the RHS Daffodils, Snowdrops & Tulips Yearbook and is reproduced here with their kind permission)
“Following the very heavy and prolonged rains in the summer of 2007, when the bulbs were sitting in saturated soil for long periods, at a time when they would normally expect to be dry and dormant, I found that I had a higher than usual incidence of bulb rot and Stagonospora curtisii. So this year I have further improved the drainage by adding one part coarse grit to the ‘mix’ and, when potting/re-potting, I now seat the bulbs on a bed of sharp sand to try to avoid the bulbs sitting in wet soil in their dormant period. With increasingly unpredictable weather patterns, this will probably not be the last adjustment that I will make.
Keeping the collection healthy
I have mentioned disease and this is a constant challenge for snowdrop growers – do not assume that your snowdrops will not be hit by disease, or that if they are then it must be someone else’s fault. Whilst measures should be adopted to guard against introducing disease into the collection, the best way to guard against disease is to do everything possible to try to ensure the good health of your plants. I have already mentioned the importance of ensuring that the plants are fed well, and this cannot be overstated in helping to keep them healthy, and it is equally important that the soil is free draining and that the bulbs do not sit in soggy conditions when they are dormant.
Good hygiene is essential – none of us wants to spread disease around our own collection, or for that matter to pass it on to anyone else, so at various times of the year, when it is necessary to handle the snowdrops, and always when I am dealing with plants that I suspect may have a problem, much washing of hands takes place between handling the different plants, as well as ensuring that any tools used are dipped in Jeyes fluid, or a similar garden disinfectant. I know that some of the commercial growers go one step further and use a different set of tools for different parts of their growing area.
Newly acquired plants are carefully examined for any sign of a problem and then all of them are routinely held in quarantine for at least a year, irrespective of whom they came from. Indeed, some could remain in quarantine for up to three years if the source of the plants has had any ‘problems’ in the past. Only after a minimum of a year, and after checking that they appear to be healthy, are newly acquired snowdrops then planted out amongst the main collection.
Here I must touch upon the vexed question of fungicides, which are a general problem for private gardeners due to the lack of available products [1]. Furthermore, fungicides may be curative or preventative and are not necessarily both. Whilst some growers routinely spray with fungicide, two or three times annually, to provide some protection against infection, there are limits to what can be done to save infected plants and in most cases, particularly where the plant is a common form, the best course of action is to carefully lift and destroy both the plant and the surrounding soil. If the infected plant cannot be removed immediately then, as a holding measure, I isolate both the plant and the surrounding soil by dusting them with Bordeaux Mixture, to help stop the infection from spreading. If a modest spraying programme is envisaged, the fungicides used should be as varied as possible, using different classes of fungicides so as to reduce the likelihood of fungicide resistance occurring.
Constant visual examination is essential when the plants are in growth and I check daily for any signs of problems. Any plant that looks in any way out of the ordinary is suspect and the policy that I operate is ‘if in doubt, chuck it out’, on the basis that it is better to do this than to take a chance and put the rest of the collection at risk. If disease is found, or suspected, both the plant and surrounding soil is immediately removed and destroyed. A plant from a different genus is then planted in its place and the surrounding Galanthus are given a precautionary drenching in fungicide. Care is needed here, in that many other bulbous species may be attacked by the fungi likely to attack snowdrops.
The only exception to my policy of destroying infected plants is for rare plants, which have been attacked by fungal disease, where I will attempt to save them. Any infection on the leaves and stem must be cut out and any infected bulb scales must be peeled back until the bulb is ‘clean’. Then the plant must be soaked in fungicide and, when it is dry, dusted with sulphur powder and then potted up in sharp sand so as to minimise conditions for re-infection and to encourage strong root growth. The plant is then kept in quarantine, with further applications of fungicide after about two weeks and during the next growth cycle. If the plant remains in sharp sand for an extended period, it is sensible to give it some liquid feed. I then cross my fingers and wait as, whilst many of the plants treated in this way appear to recover, success is by no means guaranteed. The surgery that I have described can be quite traumatic, not least for the surgeon (!), and is best left to an expert, particularly one who has access to an effective fungicide. If damage to the infected bulb is extensive, twin scaling is the best option and, in expert hands, good results have been achieved, saving rare plants that might not otherwise have survived. There is of course no treatment for plants attacked by virus.
As soon as I can, and in order to further reduce the risk of total loss of rare forms, I plant bulbs of the same form in more than one place in the garden, get a bulb twin scaled and, as a last line of defence, I place ‘back up’ bulbs with trusted friends.
I keep a log of ‘problems’ so that any trends can quickly be detected e.g. plants grown in a particular part of the garden, plants coming from a particular source, etc.”
[1] Since this article was originally written a very useful article by Gordon Hanks ‘Fungicides for amateur daffodil growers’ which, with a few stated exclusions, includes all fungicides available for amateur use on ornamental plants, has been published in the 2009-2010 Edition RHS Daffodils, Snowdrops & Tulips Yearbook.
I would suggest that it would be a good idea for those interested to source those Yearbooks to read the full arcticles.
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This is very interesting, and is what I was hoping for. The personal experiences of other growers would be useful too.
In Chris' article he says "I have already mentioned the importance of ensuring that the plants are fed well, and this cannot be overstated in helping to keep them healthy". In other articles I have read that it is important not to feed plants 'too much' as this will make them more prone to disease. It seems that there is a fine line to be drawn here.
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Anne - You're correct there is not much on the internet.
This is what I have found out, not much to add though:
Given that many if not most commercial Hippeastrums have stag it seems the huge bulbs manage to keep ahead of the damage. I have thrown out most of my big H. striatas for fear they have it, though, having said that I have never seen them exhibit leaf problems, just reddish coloration where the bulb scales have been damaged - presumably by stag. Hippeastrum will show this reddishness when they are mechanically damaged as well so it can get very confusing. Ditto I presume Galanthus. I have a friend in Holland who has promised to ask the big growers of Hippeastrums what the best solution might be.
I have had this reddishness on Galanthus bulbs here, scales damaged and the eventual loss of the bulb. I toss or quarantine. It could be damage from sciarid fly larvae that starts a bulb rot of sorts, even a malicious bulb mite if one for G.s exists. I have NEVER seen any foliar spotting or twisting and am convinced the damage starts first on the bulb not the leaf. The damaged areas feel a bit slimy too. Maybe this is not stag. I suspect whatever it was took out my big clump of Rosemary Burnham several years ago.
Carbendazim is considered the best fungicide for stag. It is not available here. Benomyl was available here until a few years ago as mentioned before. One or two websites say that benomyl degrades as carbendazim (with water or soil - I can't recall which - and quickly) so presumably it should be just as good if, one has a pinch around from bygone days. I have an email in to one of the tech guys at Bayers on stag, carbendazim subs and a better solution.
This year I have seen stag on a few locally traded bulbs and now foliar problems, the first time ever but nothing as bad as the shots Maggi posted. They have been moved away from the rest and treated doubled strength with benomyl - kill or cure.
I think Chris is absolutely correct about wetness during dormany being one culprit and most likely the most important factor. I noticed in the last couple of years when de-potting in August some pots were still damp after a June drying off, the very dampest few pots had the reddish stagy looking bulbs. This past summer here was very damp even under greedy trees so it will be interesting to see if in ground plants are affected. In mid to late May I intend to plant a few seeds of annual rye in each of the snowdrop pots, then move them under cover; this way the rye will sprout, dry the soil out and then die of drought. I should be able to gingerly water a few pots of drops that dislike complete drying out (I find setting the pot in a 1/4" of water for just a few minutes gives just enough humidity in the pot to prevent dessication but the moisture is well away from the bulb zone).
Like you I wish someone would publish a definitve scientific report on stag given that affects such important crops as Daffs and Hippes. No doubt in the future someone will discover the stag resistant gene or stimulate an existing one (if anyone is interested in such a project). Perhas it will be inserted in all the named cultivars - then we will have to buy the new genetically-modified version starting from scratch again. Even more expensive? >:( That is until another horror comes along!
johnw
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Thank you John. So far, hawk-like observation, isolation/disposal, and fungicide drench seem to be popular, along with peeling of damaged bulbs back to healthy tissue and/or chipping for specially valuable varieties.
Does the infection affect the roots? I'm asking this because it is relatively easy to dispose of a clump with the soil around the bulbs when they are grown in a plunged basket, but fragments of roots may remain.
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I have a systemic fungicide(PLANT DISEASE CONTROL) that contains 50g/l of Carbendazim made by DOFF PORTLAND LTD, Ariel Way,Watnall Road,Hucknall,Nottingham,NG15 6DW. They still have a webpage http://www.doff.co.uk/ and a fungicide listed but I cannot read what it contains.It may have gone of the market as I have it for a long time.
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Michael - I think Carbendazim is now banned in the EU. The current DOFF systemic fungicide is said to contain myclobutanil but no data sheet is available so it is unclear whether it would be effective against Stag. I suppose one could email them & ask.
Edit - I have just done so & will report what they say.
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Does the infection affect the roots? I'm asking this because it is relatively easy to dispose of a clump with the soil around the bulbs when they are grown in a plunged basket, but fragments of roots may remain.
A good point Anne. Usually I have discovered the redness on the bulbs when dormant so it's hard to say if the roots - long since dried up - were affected as well. I guess that risk would further strengthen the idea that ground where they were should not be replanted for 5 or 6 years.
johnw
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Michael - I think Carbendazim is now banned in the EU. The current DOFF systemic fungicide is said to contain myclobutanil but no data sheet is available so it is unclear whether it would be effective against Stag. I suppose one could email them & ask.
Edit - I have just done so & will report what they say.
This is the email I sent to DOFF:
I'm trying to find a fungicide which will be effective against Stagonospora on narcissus. I used to use Carbendazim which seems no longer available. Will your current systemic product (myclobutanil) be of any use?
Many thanks.
Here is the reply:
Thank you for your recent enquiry.
(Stagonospora curtsii) Yellow to brown lesions at leaf tips. Elongate reddish brown leaf spots. Small black pycnidia form in necrotic areas.
The fungus survives in the neck and between scales.
Disease is favored by mild, moist conditions. Spores are spread in splashing water.
The fungus infects members of the Amaryllidaceae. Treat bulbs with hot water. Protect plants in the field with fungicides. Make first application as leaves emerge.
Doff Systemic Fungus Control contains myclobutanil (controls black spot, rust and mildew). We have tested our products on a limited number of species, we would advise for you to contact your local garden centre for further advice on which fungicide to use.
Regards
Sharon Milner
Technical Department
Doff Portland Limited
Very helpful!
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What a feeble reply from the manufacturer. >:(
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a joke!
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Typical :( And the garden centre would definitely know,wouldn't they. ???
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I'd be amazed if they'd heard of the disease, let alone know the treatment. Might be entertaining to ask though!
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What a feeble reply from the manufacturer. >:(
I wonder whether these people actually manufacture the stuff or just buy in bulk from elsewhere & repackage under their name?
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Feeble response either way, in my opinion. They should be able to answer questions like that whether they're making it or distributing it.
Wonder what the response would have been about the toxic effects.... how much would they know if a poisoning had happpened with the wretched stuff? I thought that manufacturer and distributor would be required to know as much as was possible about products.
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I agree Maggi.
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I suspect the DOFF reply is all they are allowed to give. They will have a licence for specific indications and would not be allowed to recommend use outside of those. It looks like the licensed indications are black spot, rust and mildew.
Chad.
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In snowdrops does Stagonospora look like the yellow leaf in the middle of the prize winning clump of 'Robin Hood' shown in KentGardener's picture on the snowdrop forum's 'RHS Halls feb 2010' thread?
Chad.
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Hi Chad, welcome to the Forum.
We were speaking about that dodgy leaf in the coach on the way home for the Dunblane Early Bulb day.........it certainly looked very suspicious, doesn't it? I'd have removed that before exhibition if it were mine.
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I think the yellow leaf is an illusion but there is something brown
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Found in a basket yesterday (now binned - fortunately not a very choice var). I think this is 'stag'.
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This what I have diagnosed as Stag on Narcissus rupicola. Can anyone confirm my diagnosis?
Further to my post on Feb 12th (Reply no 12). Bayer market 2 fungicides, Dithane & Systhane. On Feb 14th I emailed them to ask whether either would be effective against Stag. As yet I have had no reply.
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Anne's and Gerry's pics both look like stag.
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There is another, mixed, thread dealing with Stagonospora here :
http://www.srgc.net/forum/index.php?topic=5172.0 (http://www.srgc.net/forum/index.php?topic=5172.0) ( as well, of course as other individual posts throughout the forum.