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Produce => Pests & Diseases => Topic started by: Smileyk on August 09, 2007, 09:20:28

Title: Avoiding blight on potatoes?
Post by: Smileyk on August 09, 2007, 09:20:28
Our potatoes are just coming up and dh was at the allotment last night and was talking to potato man (the resident expert!  ;D ) and he said that with the blight around on the other allotments we should spray now to try and avoid it.  I have a problem with this as:

a). I'd like to be as organic as possible
b). he didn't say what to spray them with!

So what should I do?  Do I leave them or can I spray with something that isn't a "nasty" chemical?

Advice please?
Title: Re: Avoiding blight on potatoes?
Post by: Barnowl on August 09, 2007, 12:37:57
There's no cure I'm aware of , but I think Bordeaux mixture is the usual preventative...

http://www.organiccatalog.com/catalog/product_info.php?cPath=61_181&products_id=517 (http://www.organiccatalog.com/catalog/product_info.php?cPath=61_181&products_id=517)

.... I'm sure someone will correct me if I'm wrong.
Title: Re: Avoiding blight on potatoes?
Post by: Smileyk on August 13, 2007, 11:45:25
Okay potato / blight experts out there.  Potatoes are through the ground and we've just earthed up.  There has been blight on the other allotments so do I need to spray and if so when?

Any help appreciated!

Thanks  ;D
Title: Re: Avoiding blight on potatoes?
Post by: tim on August 13, 2007, 11:59:03
No 'expert' but - Bordeaux mixture IS the only 'non-nasty' - every 2 weeks - every leaf - top & bottom!

And respray after rain!  That's why so many have lost crops this year - there wasn't a day you could spray!
Title: Re: Avoiding blight on potatoes?
Post by: telboy on August 15, 2007, 22:30:10
Very true Tim,
Went away for a week in July. Before I left the main crop was upstanding & looked healthy as one could wish.
Came back & the tops were over with the dreaded symptoms.
Took off all the haulms to the ground/left for three weeks/lovely dry spell/ dug up the lot.
After drying/bagged/now inspecting after only one week. Lost 10% already.
Not growing Maincrop next year. (not even the Sarpo rubbish)
After 30 years, this is the only problem I've ever given up on.
There will be others no doubt - the spuds will be replaced by peas. Easier on the back also!

Title: Re: Avoiding blight on potatoes?
Post by: theothermarg on August 16, 2007, 21:32:13
silly question!!!! going by the fact that it sometimes afects my toms in the G/H
it seems to be airbourn so provided the spuds are put in clean earth wouldn,t covering them with fleece stop? it has anyone tried?
marg waiting to be shot down
Title: Re: Avoiding blight on potatoes?
Post by: Robert_Brenchley on August 16, 2007, 23:19:38
The spores are microscopic, and I can't see fleece stopping them. It would be nice and warm and damp imder the fleece too; ideal conditions for fungi.
Title: Re: Avoiding blight on potatoes?
Post by: theothermarg on August 17, 2007, 22:19:23
Quote from: Robert_Brenchley on August 16, 2007, 23:19:38
The spores are microscopic, and I can't see fleece stopping them. It would be nice and warm and damp imder the fleece too; ideal conditions for fungi.
mmm yes you make a very good point there. i think my plan next year is to go for 1sts and 2nds put them in early/ dig them up early and try spraying them
marg
Title: Re: Avoiding blight on potatoes?
Post by: growmore on August 21, 2007, 09:05:22
I think The most effective spray available to us for blight  is Dithane 945 ..

Title: Re: Avoiding blight on potatoes?
Post by: tim on August 21, 2007, 09:24:11
Certainly effective, but less 'organic' than Bordeaux'?

Is it systemic, or must foliage be sprayed over & under?
Title: Re: Avoiding blight on potatoes?
Post by: dandelion on August 21, 2007, 09:34:32
Is traditional copper fungicide The same thing as Bordeaux mixture?
http://www.lovethegarden.com/products/pestdisease/murphyfungicide.html
I used it on my toms after first signs of blight and it has been effective so far.
Title: Re: Avoiding blight on potatoes?
Post by: growmore on August 21, 2007, 10:59:55
Tim, It isn't systemic and you have to drench same as with bordeaux..

Title: Re: Avoiding blight on potatoes?
Post by: tim on August 21, 2007, 11:12:22
Thanks - & less 'organic' than Bordeaux?