Stagonospora infection - collected threads

[Alan_b]

Vive la difference ...

If I could tell la difference I might vive it but all these societies seem way too similar to me.  For example, what do you grow in a Cottage Garden?  Hardy Plants!  So why on earth do we need a society for each?  And if you like bulbs, as I do, we don't have an Atlantic Bulb Society so it's a complete free-for-all in the UK with every plant society under the sun laying claim to bulbs.

[Tim Ingram]

I suppose you 'pays your money and makes your choice'. (And objectively you are probably right Alan but you won't find much support for the idea!). A lot depends on whether you have been involved in running societies either on the larger or smaller scale, and to be honest the close and friendly relationships you make with other people which enlarge your view of the world. And how much you wish to contribute to them or just enjoy what they provide. (Not a lot to do with Stagonospora! on this thread - my apologies).

[Derryclare]

I too would welcome a little more detail about using peracetic acid to prevent/combat Stagonospora curtisii.  Having read Robin's letter in the AGS journal and having one or two suspicious lesions on plants (yes please - 'good' photos of typical symptoms would be a great help) I have obtained a small bottle of the chemical.  The sentence I am interested in reads 'a 5% solution of peracetic acid diluted in water to a concentration of 1: 200 can be used to soak bulbs for up to 1 hour but a stronger solution for a shorter time can be used to treat infected bulbs' (my italics).  How much stronger/shorter please?

The chemical is clearly nasty stuff; my local home brew store had no licence for it but a local landlord approached a brewery that supplies his pub.  Assurance was required that I knew what I was doing (the science degree sorted that) and the bottle is covered in hazard labels.  I'll be using thick gloves and a visor.

Quite what the drinkers in the local made of the audible murmur 'I'll have your supply of acid for you on Friday' remains to be seen!

[Alan_b]

The other issue is whether the treatment has some specific action on the Stagonospora or just kills-off the exterior parts of the bulb that are affected by it.  Steve Owen advocates stripping a bulb down to healthy tissue, even if that leaves little remaining, on the basis that radical treatment is effective and the bulb will grow back to normal size in due course.   

[johnw]

The chemical is clearly nasty stuff;...................... Quite what the drinkers in the local made of the audible murmur 'I'll have your supply of acid for you on Friday' remains to be seen!

Derryclare

Just how nasty?

I also wonder if tunics should be removed.  As in the hot water treatment as per Hippeastrum I wonder if for smaller Galanthus one should adjust both concentration and time according the size.

No word back yet.

johnw

[Derryclare]

Thank you for your responses and interesting suggestions.  In answer to Johnw, it is nasty enough for it to have a specific licence.  I only know what is mentioned on the web as I have retired and no longer have access to CLEAPSS information.  Wiki lists a range of hazards ranging from skin irritation (another site mentions peeling of skin on contact) to respiratory damage (I do not intend to use it indoors).  I will certainly want to try it first on a straight G nivalis rather than a named cultivar in case of damage to the bulb tissue.  I do like the fact that it will break down to harmless oxygen, acetic acid, water and carbon dioxide rather than lingering as a toxic molecule as some of the fungicides do.

I really hope that some of the other SRGC contributors will be able to give details of use on Galanthus.  For now my small bottle can sit safely in a locked outbuilding.

[Jupiter]

Toxic chemicals are in plants too! Ironically chemicals from plants are more likely to be toxic, or at least biologically active, than man made 'synthetic' chemicals.

Thi; http://www.jstor.org/discover/10.2307/3758431?uid=3737536&uid=2&uid=4&sid=21106495428553  was published back in the 70's and looks like a good little article. I haven't got access to the full article at home; I'll have to wait til I get to work on Monday and have a read. There are a bunch of papers on garlic's anti-fungal properties. Most of them seem to be medical, dealing with dermatitis.

[Alan_b]

I was a bit nervous about these leaf symptoms on a group of 'Trumps'.  I first noticed it at the start of April and thought it might well be indicative of Stag.  So I dug the clump up today but the bulbs themselves cleaned up to be absolutely pristine.  Was I worrying over nothing?

[Maggi Young]

I've  collected a number of previous threads on this subject here - I was moved to do so by a recent conversation I saw  ......

 Q: Does stag cause snowdrop flowers to abort and turn to a brown mush in the spathe?

A:  Yes it can do but the major sign is reddish brown marks on the leaves and scapes plus difformed leaves. Sweeten up your soil with extra humus and Trichoderma harzianum mycorhiza!
 And use less fertiliser then.

[Alan_b]

the major sign is reddish brown marks on the leaves and scapes plus deformed leaves.

Whilst this is quite true, if you dig the bulbs up and remove any dead outer tunic you will find that Stag.-infected bulbs show signs of rot and discolouration.  I think it's reddish-brown again but I'm a bit too colour-blind to state this with any authority.  But my point is that whilst you might see signs above ground, it's that state of the bulbs that clinches it. 

[steve owen]

Stagonospora also has a very distinctive smell. Not a pleasant one either!

[mark smyth]

really? like what? How do you know? Maybe we could train labradors to sniff them out

[Alan_b]

Maybe we could train labradors to sniff them out

Sorry, Mark, I already suggested this idea (well dogs anyway).  Maybe Emma could train her Frenchies to make themselves useful?

[kentish_lass]

Stagonospora also has a very distinctive smell. Not a pleasant one either!

Steve - is it an intense oniony sort of smell?! 

I am plagued with Stag and was peeling back a bulb of Sentinel tonight and noticed it had a very strong smell.  Every time I go outside to take photos I end up spotting problems in the pots or beds hence you have not heard much from me this year on this forum.  I am starting to wonder if I am imagining Stag now and have just become completely paranoid.  At the end of my tether and getting so fed up with it.   My old stash of Carbendazim is running very low now - what is everyone else using?

[JimF]

 
I am plagued with Stag . . . .  My old stash of Carbendazim is running very low now - what is everyone else using?

I use a natural bacterium called Streptomyces lydicus with amazing success. (Sold as Actinovate in the US.) On heavily infected test bulbs, it ate away the dead and dying tissue containing the stag. It was explained to me that it works like maggots used to treat gangrene - it out eats the other bacterium - feeding only on dead or dying tissue.

When repotted in August the top part of each bulb had grown a brown skin attached in the middle to the remaining scarred, unskinned scale connected to the bulb plate. No, I didn't think to take a photo  .

Some nurseries here (Washington State) use is as their main fungicide. It's approved for organic gardening here. Sorry if this sounds like an advertisement, but it saved many rare galanthus and narcissus for me.