Potato Blight

[andyt]

don't s'pose there's anything about grey mildew/mould on the underside of sprout leaves?

[Turf cutter man]

If you think it is blight you can use bordeaux mix...or bordealise in france. We had blight on our tomatoes last year and sprayed them a couple of times with bm and got quite a reasonable crop while everyone I know lost theirs.

it is classed as organic and can be used up to a few days before harvest. It is based around copper sulphate and the reason it is allowed under organic conditions is that it breaks down quickly and does not effect soil stucture etc.

Be warned it is blue so colours the plants blue. You can get a coulourless one but...that is not organic...so I can't see the point.

we are having a lot of rain here as well....all ok so far......

[Annpan]

don't s'pose there's anything about grey mildew/mould on the underside of sprout leaves?

as in - brussel sprouts?
general brassica troubles mentions

Downy Mildew
Yellowing of upper surface. White furry fungus growth beneath. Usually restricted to young plants; over crowdingg and moist atmosphere encourage it's spread. Growth severely checked.
Treatment - Spray with Mancozeb at the first sign of disease.
Prevention - sow seeds in sterilised compost. Choose a fresh site for raising seedlings if downy mildew has been a problem in the past.

The book is 'The Vegetable and Herb Expert' by Dr D.G. Hessayon -there is a huge range of these gardening books by the same author - I find it really useful for at least diagnosing (although it isn't organic, so I find treatments elsewhere sometimes)

[ina]

it is classed as organic and can be used up to a few days before harvest.

Don't know about France, but in the UK you can only use it (in certified organic production) after derogation - special license from the certifying body after you've proven that you've tried everything else and failed. They are phasing it out altogether, now that there are more and more blight resistant varieties available.

[VirGin]

Thank you to everyone for responding and supplying links. No, there's no mould on the underside of the leaves. The Capsid bug damage seems quite different to what I've got, so don't think it's that.

The variety I'm growing is Amandine, which is a cultivar of early potato, descended from the varieties Charlotte and Mariana. According to http://www.europotato.org/display_descr ... e=Amandine it has low to medium resistance to late blight, so there's my problem. It is a rather delicious potato tho, so worth trying.

I bumped into my neighbour (the one with the enormous potager ) and described the leaf damage - he said it is "mildiou" i.e. blight. He didn't have the time to pop by to inspect it, but based on my description he didn't hesitate with his diagnosis. I therefore succumbed to the magic blue liquid (bouillie bordelaise). Am considering harvesting one plant to check on the state of the potatoes - stupid question, but can one eat potatoes harvested too early (before any flowering or dying back)?

[ina]

but can one eat potatoes harvested too early (before any flowering or dying back)?

Yes, you can; they just won't taste so nice.

To avoid blight in the future, try spacing them, a bit wider - gives wind a better chance to get through and dry the plants out; also, if possible, arrange the rows in the main wind direction, for the same result. (That's two of the main methods used in organic farming to reduce the impact of blight.)

[Millymollymandy]

By your post I can tell you are in France! I'm growing Amandine too and they have already flowered and the 'new' spuds are enormous! I actually prefer smaller new potatoes!

Anyway where are you?


Edited to say, ignore me, I read back and you've already said you are in Aveyron and it keeps raining there. So that's probably why mine are ahead of yours!

I'd dig up a spud if I were you to have a look.

[andyt]

Thanks Annpan, it's probably the overcrowding thing. Hey ho!!

[casa_tyr]

We are in southern Spain, and often have the same problem.

Your pictures look like 'early blight', which has the black dots, with the leaves yellowing and the plant looking pretty iffy. It eventually affects the potatoes themselves if you don't treat them with an anti-fungal spray.

Potatoes can also get 'late blight', which results in the slimy blackness that others have described.

If you treat early blight, your potatoes will be just fine - we had it this spring, and are now enjoying our great potatoes!

Also make sure to use fresh seed potatoes to avoid passing on the disease, and, of course, rotate your crops.

[oldfella]

Had blight on my taters sprayed them, and left for them two weeks but the foliage died back and the neighbour suggested I left them for another two weeks which I did, and had quite a good result.

[MINESAPINT]

Potato blight league table: http://web.ukonline.co.uk/suttonelms/pot17.html[url][/url]

I try to grow blight resistant varieties. This year I am trying Orla, Lady Balfour, Pentland Dell, Golden Wonder & Kestrel.