Topic: Dreaded Potatoe Blight

[craggle58]

My potatoes have only just started flowering and are already showing signs of blight. The lower leaves are turning yellow then black and shrivelled. Is there anything at all I can to combat blight which has already set in? The potatoes are still very small and if I start cutting the tops down it will mean a virtually zero harvest. Has anyone else got blight this early? I think it is symptomatic of the mild winter. Other pests and diseases (aphids very bad) seem very prevalent this year.

Another reason could be local agriculture. Farmers seem to have gone big on potatoes in my local area this year. How do farmers deal with blight?

[galina]

That does not sound like blight to me.  The top leaves get brown spots at the edges of the leaves as a first sign of blight, not what you describe.

The picture in this article gives a good representation of potato blight.
http://www.nature.com/news/2009/090909/full/news.2009.893.html

If you see this sort of thing, it is time to cut down the foliage, then lift the potatoes 2 weeks later.

There are copper sprays that work BEFORE blight has started (like Bordeaux mixture), but I have never used them.  We tend to grow resistant potatoes, such as the Sarpo varieties and (first time this year) Carolus, which is said to be immune against blight (I am looking forward to seeing this!).

Yellowing from the bottom can have various reasons, including early potatoes being ready for lifting.

[chriscross1966]

THat's not blight, the leaves don't go yellow, they go brown and rot in situ, what variety are they?

[craggle58]

I have had it confirmed as blight. Will this also affect my tomatoes which are about 10ft away in a double greenhouse? I cant believe how early I have got it. I have had it before but usually around late July.

[bluecar]

Hello Craggle58

This is very early for blight. Do you have any photos you could upload? Who has confirmed it as blight? Where are you located so, that if it is blight, sites near you can start to be more vigilant in their observations.

Regards

Bluecar

[craggle58]

Several people at the allotment confirmed it. The guy with the next door plot has already started cutting the tops down. I am located in Pontefract, Yorkshire. I will try and get some photos tomorrow but the camera on my phone is terrible. Will the same blight also attack my tomatoes? Is it worth spraying my tomatoes with a preventative blight treatment?

[Flighty]

This blog post may be of interest -

http://glallotments.blogspot.co.uk/2014/06/blighted.html

[bluecar]

Hello Craggle58.

Blight will attack your tomatoes, so as Galina says, a spray of Bordeaux mixture will help to prevent it providing its not already started. Potatoes leaves normally go yellow and then black as they die down. If blight is attacking you need to act quick and cut away the foilage.

Have you compared your plants against the link Galina has given?

Regards

Bluecar

[craggle58]

Yes it definitely is blight. It's spread over 3 varieties at the moment. Lady Crystal, kestrel, and Desiree. Only Rudolph seem unaffected. This is the first year for ages I haven't planted some Sarpo. Bloody typical. I'll try and get some bordeaux mixture for the tomatoes as they appear to be unaffected at the moment. This could be a really bad year as half my plot is dedicated to potatoes and tomatoes.

I've just read the blog posted by Flighty. Osset is not far away at all (about 12 miles). I have checked the fight against blight website and there is a confirmed agricultural case near pontefract:

http://www.potato.org.uk/fight-against-blight/blight-incidents

[Digeroo]

I have total wipeout on one of my 1/2 plots.  We have only had one rain storm for several weeks, and no blightwatch alerts. 

Thought to start it was early blight but the stems have gone as well.

I am just about getting one meals worth for two from each potato from my earlies, they needed another few weeks to really start to fill out.

Tomatoes did not go out until after the rain so are ok at the moment.

[bluecar]

Not good news then - I hope by cutting the stalks off you still get a reasonable crop. Again as Galina states it's best to leave the 'spuds' underground for a couple of weeks as this lessens the chance of them being affected.

As I'm away at the moment I've got my fingers crossed that all is well in the West Midlands.

Regards

Bluecar

[craggle58]

I have bought the Bordeaux mixture today. It feels a bit like bolting the proverbial stable door........and not cheap at £4.50 to make 7.5 litres. I have applied it to the tomatoes which seem unscathed at the moment. Is it worth applying some to the potatoes that appear as yet unaffected or is contamination now inevitable? The potatoes are all together in a 20ft x 10ft area.

[Pescador]

Craggle,
If you think it's around you, get the spray on now, as it's a preventative not a cure.

[strawberry1]

SW and rain forecast later after weeks of sun. My neighbour asked me to use bordeaux on hers if needed, so will go up this morning and spray hers. I have two raised beds of potatoes, both 4 x 8 feet and one contains charlotte, the other blue danube (sarpo type) I had a good think last night and have bordeaux stashed in my cupboard but have decided against spraying mine. Charlotte tops are susceptible but the roots are resistant so my plan is that if it strikes, then I will cut the charlotte tops off and I am leaving blue danube. I have spent quite a time building up organic matter in the soil and the worm population has increased a fair bit, so not worth it for me as they would be affected by copper sulphate

I have 22 tomato plants at home, strillo and ferline. I have moved all the 16 outdoor strillo buckets against high walls as they might get some shelter. Other than that I am keeping my fingers crossed. Ferline and strillo have been good in the past few years. When does the bordeaux ban come in?

[craggle58]

I didn't know anything about Bordeaux mixture being banned. It's still on sale. Is it considered dangerous by the Health & Safety police?

[antipodes]

I would be surprised if Bordeaux mixture was banned as it is declared safe for use in organic cultivation...
4.50 sounds expensive for 7 litres of Bordeaux mixture???? I get a packet for about that but it lasts for ages (i.e. several seasons) and I spray my spuds, tomatoes and grapevine !

[craggle58]

The Bordeaux mixture was from a quality but expensive local independent horticultural shop (Pleveys). Do people tend to apply it as a matter of course every year?

[Jayb]

Here's a thread from 2013 discussing Bordeaux Mixture  http://www.allotments4all.co.uk/smf/index.php?topic=74809.0

Do people tend to apply it as a matter of course every year?

I avoid it as much as possible.