How does Blight affect crop yield...

[snohare]

...if you chop off the haulms from your potatoes ?

I received Blightwatch warnings for the postcodes of all three places I have potatoes planted today. Apart from one solitary bucket of PFAs, they are all in places I cannot visit easily, due to distance or lack of transport. So I was going to go into town tomorrow and chop the haulms off my plants at the allotment.
What I am wondering is, how much of a crop will I get if I do this ? Virtually all I planted were second earlies, if my vague memories serve me rightly (I've lost the labels I put in), with the exception of some Red Duke Of Yorks. They all went in at the end of end April.
Has anyone any experience of this sort of situation ?

[Alison]

I've been getting the odd blightwatch warning since May (although far fewer this year than normally) and I just cross my fingers and hope. Just cos you get a warning doesn't mean you'll get blight it just means that the conditions are right so the likelihood is higher than on other days. As soon as you cut the haulms down the potatoes will stop growing so you'll get the crop that you have at that time. You could cut them down as a preventative measure but would you have done that if the warnings had come 6 weeks ago, say?

[snohare]

I take your point about not doing it earlier. My problem is that blight is all over the place around this area, even when there have been no warnings I have seen patches where the gardeners have either removed the shaws due to alarms, or they have actually been stricken by blight. This isn't tatties that are ready either - I know because I see them regularly.
Given that conditions are absolutely ideal for the spores to be active - muggy, hot, verging on rain - and that sporadic outbreaks are already happening, I am wondering if I dare wait. I normally only go to the allotment once a week...by next Monday they might be withered stalks, with the tubers ruined.
Next year I will be growing some Sarpos, I don't care if the taste is not great I can't afford to lose the whole crop !

[SarzWix]

I'd go and be prepared to take the tops off if it was me. Dig a plant up and see what's under it. If they've been in for May, June and July, that's over 12 weeks which should be just enough to get some tubers?

[VirginVegGrower]

Agree with Sarzwix!

[SarzWix]

Just checked the gardening forecast for Aberdeen for the next week, and it's showing humidity over 90% for at least half the day, for 6 out of the next 7 days. Definitely dig one up and see what you've got!
If the crop is a bit pathetic, what are the chances of you being able to cover the soil beneath the plants? That might stop any spores getting to the tubers? A layer of cardboard, newspaper, straw, or grass-clippings might be enough of a barrier?

[SarzWix]

Metcheck.com - Global Weather Forecasts - [Updated on 03 August 2011 at 0:00] - Weather Feeds - Live Data - Long Range Weather Forecasts

[Aberdeenplotter]

I'd go and be prepared to take the tops off if it was me. Dig a plant up and see what's under it. If they've been in for May, June and July, that's over 12 weeks which should be just enough to get some tubers?

Spot on Sarz. I had signs of blight on my second earlies at the weekend. Tried a stem of kestrel and discovered humungous spuds. Baking spuds now on the menus and shaws/haulms cut off. I also tried the same with amour and although the spuds are of useable size, they are not away from the stem yet so have left them for a few days as that can make a huge difference at this time of the year. I am checking daily and if they deteriorate, it will be off with their heads without hesitation. Better small spuds than no spuds. My lates are blight resistant - sarpo mira - and are growing like tryphids.

[Aberdeenplotter]

btw, covering the soil is unlikely to help. moisture running down the stems will go directly to the spuds.

[snohare]

Okay folks, thanks very much for the info. Context decides everything, so it is much appreciated.
I didn't know that about the forecast for humidity, and that certainly changes the picture. When I was last in, Aberdeen had the haar (sea fog) big time - more perfect conditions for blight you could hardly see.
My get up and go has just got up and gone (CFS), so I have asked a friend who does veggies to go check on them after work today, and if there are any symptoms at all to chop 'em down. If there aren't any, then I can go into town on Friday (if able) and check them then, see what is happening, have a furtle, etc. Like you say AP, a few days may make all the difference.
I hadn't even checked to see what tatties are there, it didn't seem that important as they weren't going to grow any faster for me looking at them, wish I had now !
Aye, I feel it in my bones, they're dooooooommmmed....