Stagonospora infection - collected threads

[snowdropman]

I also dug some other bulbs and wondered if they had stag, or is the orangey colour quite normal? 

Jennie - if you gently peel/scrape away the paper thin brown skin on the bulb then (with the exception of a couple of the species snowdrops) the outer scale should always be a clear white colour.

The brown/orange colour on your bulbs is where the bulb scales are rotting following attack by the spores of stagonospora curtisii.

Just soaking the bulbs in a fungicide will not, in itself, do anything to save the bulb - you must first completely remove the infected parts of the plant. On the bulb this means peeling back the scales of the bulb until you come to a completely white scale. On the leaves/stems this means removing the infected part, back to what looks like a 'clean' area.

Only once you have performed this surgery is there any value to soaking the bulb/drenching the plant in a fungicide - the fungicide will only help to protect the plant from a future attack, it will not cure/kill an existing attack.

Some snowdrop growers routinely spray their snowdrops with a fungicide spray as soon as the leaves have emerged from the soil, immediately after the plant has flowered and then again when the leaves are dieing back - in all 3 instances both the purpose, and the effect, of the fungicide spray is to protect the plant from being infected.

Once a plant is infected, no amount of spraying/soaking will do anything to kill off the attack - if you do not first remove the source of the infection, then the plant will just die and/or be a potential source of spreading infection to other plants.

[Gerry Webster]

There are a number of references in this thread to a fungicide or, even better, a "good fungicide". Since the number of fungicides available to the amateur has been drastically reduced in recent times I would be interested to know what product(s)  forumists have in mind (especially with regard to treatment of  'Stag', since Carbendazim is no longer available).   

[johnw]

Chris - Thanks. I have seen 2, 3 & 4 on imported bulbs but not #1 that I can recall.

Mrs. B. #12 was potted in sand as you suggest and got one fertilising since.  Fingers crossed.

johnw

[snowdropman]

There are a number of references in this thread to a fungicide or, even better, a "good fungicide". Since the number of fungicides available to the amateur has been drastically reduced in recent times I would be interested to know what product(s)  forumists have in mind (especially with regard to treatment of  'Stag', since Carbendazim is no longer available).   

Gerry - this is a frequently aired topic on the forum and a search of the archive should turn up some suggestions - as you correctly say the amateur grower is increasingly restricted in the products available.

Gordon Hanks wrote an authoratitive article in the 2009-2010 edition of the RHS Daffodil, Snowdrop & Tulip Yearbook entitled 'Fungicides for amateur daffodil growers' in which he sets out details of "all fungicides available for amateur use on ornamental plants", together with information on the law and sources of information on approved pesticides.

[snowdropman]

Chris - Thanks. I have seen 2, 3 & 4 on imported bulbs but not #1 that I can recall.

Mrs. B. #12 was potted in sand as you suggest and got one fertilising since.  Fingers crossed.

johnw

John - good luck with Mrs B.

Other symptoms of stagonospora curtisii which, in my experience, appear less frequently are

5. tiny brown spots appearing on the flowers after rain

6. small rough brown bumps appearing on the spathe

[kentish_lass]

I also dug some other bulbs and wondered if they had stag, or is the orangey colour quite normal? 

Jennie - if you gently peel/scrape away the paper thin brown skin on the bulb then (with the exception of a couple of the species snowdrops) the outer scale should always be a clear white colour.

Chris - thanks for the further info on the stag infected bulbs.  I will have to perform surgery tomorrow as I have potted them now and stood them far away from other snowdrops.  I soaked them overnight in some old fungicide I have with Carbendizum.  I am horrified at your further symptoms to look out for as in my paranoia I am thinking I have them all    I noticed Britten's Kite and  Sickle had slightly wavy leaves and a few had a red mark on the flowers.

I imagine this constant wet and rainy weather is not helping matters - I wish it would stop.  Would extra grit in the soil help with Stag?  What exactly causes it?

Here is a photo of Sickle with suspect looking foliage - does anyone think this is cause for concern?  Not a very clear photo as it was late in the day.  I notice the flower in the front looks a bit droopy as well
thanks
Jennie

[mark smyth]

wet soils are supposed to spread stag from snowdrop to snowdrop

[mark smyth]

I bought Paradise Giant last year at the Gala without flowers or flowers over. They are Sickle. I'm not sure which is more expensive

[Gerry Webster]

There are a number of references in this thread to a fungicide or, even better, a "good fungicide". Since the number of fungicides available to the amateur has been drastically reduced in recent times I would be interested to know what product(s)  forumists have in mind (especially with regard to treatment of  'Stag', since Carbendazim is no longer available).   

Gerry - this is a frequently aired topic on the forum and a search of the archive should turn up some suggestions - as you correctly say the amateur grower is increasingly restricted in the products available.

Gordon Hanks wrote an authoratitive article in the 2009-2010 edition of the RHS Daffodil, Snowdrop & Tulip Yearbook entitled 'Fungicides for amateur daffodil growers' in which he sets out details of "all fungicides available for amateur use on ornamental plants", together with information on the law and sources of information on approved pesticides.

Thanks Chris. Unfortunately a search of the forum produces no useful results. Two pages from the RHS website are not encouraging:

http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=735
https://www.rhs.org.uk/advicesearch/Profile.aspx?pid=222

They state that there are no fungicides available to amateurs which will deal with leaf scorch (Stagonospora)
or basal rot (Fusarium) in Amaryllidaceae. This is confirmed by a PDF on fungicides available to amateurs which can be downloaded.

[snowdropman]

I imagine this constant wet and rainy weather is not helping matters - I wish it would stop.  Would extra grit in the soil help with Stag?  What exactly causes it?

Stagno is an ever present problem - the best line of defence against it is keeping your collection of snowdrops healthy. In the 2008-2009 edition of the RHS Daffodil Snowdrop & Tulip Yearbook, I wrote an article 'Collecting Snowdrops - Some Observations' and probably the simplest way to answer your questions is to reproduce below what I think are the relevant section of that article - hope that this helps

Chris

"I should not move on without talking about my ‘mix’ but I must emphasise that this is what works for me, in my growing conditions, and is not intended in any way to be prescriptive. What I have tried to do is devise a ‘mix’ that provides both quick release and slower release fertiliser for the plants, whilst at the same time ensuring that the soil remains free draining. My ‘mix’ comprises, two parts sharp sand, two parts John Innes No 3 [1] and one part multi compost [2] – for those snowdrops that are known to require a more acidic soil, or a chalkier soil, I adjust accordingly. Since changing to this ‘mix’, I have had consistently good results, with plants generally showing strong growth, flowering well and with good natural division.

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. 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."

[mark smyth]

Going through empty pots today I found this caterpillar. This is what I would have called a swift moth caterpillar. This one hides underground and comes out to feed at night

[Gail]

This is what I would have called a swift moth caterpillar. This one hides underground and comes out to feed at night

I think others have shown this elsewhere Mark but this is a swift moth caterpillar - big pest of snowdrops and peonies in my garden.  I think yours is a cut worm larvae, I'm sure someone else will know the species.

[johnw]

wet soils are supposed to spread stag from snowdrop to snowdrop

And yet you saw perfectly fine ones on Ram Island. As mentioned some great nivalis clumps in the city here in very damp spots. Puzzling.

Crhis - do you think peat is implicated in stag?

johnw

[mark smyth]

John I'm going back to Rams Island to help divide snowdrops so I'll be able to have a closer look for stag and if I can get back again in June the fly. Thats if I can spot them among the millions amd millions of Lough Neagh flies

[kentish_lass]

Today I have ordered everything I hope I will need to get the snowdrops in a healthier state.  I ordered 40 lattice pots, a gallon spray bottle (with battery operated nozzle) for the fungicide operation & a small tub of trachoderma.  Then went to the garden centre and bought John Innes no 3 and sharp sand with grit (all they had) and some Jeyes Fluid (for sterilising tools).  I have several bags of horticultural sharp grit already on hand.  I am thinking of adding some perlite too to lighten the mix.

All I need now is for the rain to stop so I can tackle the problems 

Before sinking the lattice pots I will drench with fungicide and possibly Pravado for the narcissus fly.  How long in between drenches should I leave - any ideas?

Have I missed anything?
thanks
Jennie