[mumofstig]

You can buy testing kits yourself, so there would be no delay in the results.
There are a few  suppliers for example
http://www.plantsbypost.com/testing-kits/potato-and-tomato-blight-testing-kit.html
and
http://www.jbaseedpotatoes.co.uk/potato-blight/blight-tester-kit

[Aunt Sally]

If you want to be a blight monitor send an email to Gary Collins    gcollins@potato.org.uk

They have a new e-mail format so please contact:

Gary.Collins@potato.ahdb.org.uk

[Salmo]

You can buy testing kits yourself, so there would be no delay in the results.
There are a few  suppliers for example
http://www.plantsbypost.com/testing-kits/potato-and-tomato-blight-testing-kit.html
and
http://www.jbaseedpotatoes.co.uk/potato-blight/blight-tester-kit

The kits are no doubt very good but at the price they are I would not want to test every suspect spot ot blemish, just those I was pretty certain are blight.

One could of course do both, test with your own kit and send a sample to Fight the Blight. They want to monitor where there are outbreaks and also to see which strains of blight are doing the damage.

[mumofstig]

The kits are no doubt very good but at the price they are I would not want to test every suspect spot ot blemish, just those I was pretty certain are blight.

Indeed, but it would mean that you wouldn't have to wait days for confirmation, which is what I said in my earlier post 

[cooperman]

Generally Potato Blight (Phytophthora infestans) does not strike until late summer ie after July It is very distinctive and rapidly spreads and plants collapse in a foetid mess.
Most people erroneously confuse "Potato Blight" with "EARLY Blight" or Target Spot (Alternaria solani) which is a totally different infection causing plants just to shrivel up and dieback - plants really look like they've been scorched, this form of blight rarely affects yields and does not need treating as the tubers are not affected.

[Salmo]

Generally Potato Blight (Phytophthora infestans) does not strike until late summer ie after July It is very distinctive and rapidly spreads and plants collapse in a foetid mess.
Most people erroneously confuse "Potato Blight" with "EARLY Blight" or Target Spot (Alternaria solani) which is a totally different infection causing plants just to shrivel up and dieback - plants really look like they've been scorched, this form of blight rarely affects yields and does not need treating as the tubers are not affected.

Are you saying that all our spraying and removal of tops has been a waste of time? One look at the Potato Council blight map will tell you how widespread confirmed outbreaks of late blight are this year. Every one of these has had a sample tested in their laboritory.

[Ice]

I think cooperman's advice might have been right if we hadn't had such a damp and dismal summer.  But there is no escaping the fact that late blight is here and very widespread.  Once you know what to look for it is easy to spot.

[Headgardener22]

Most people erroneously confuse "Potato Blight" with "EARLY Blight"

According to the RHS, "Early blight is widely found in North America, and is commonly reported on the internet. This fungus disease of potatoes is caused by Alternaria solani and A. alternata. It is not a common problem in British gardens and is frequently confused with magnesium deficiency."

I realise that what we are getting now is late blight but is the RHS correct or do we get early blight as well in the UK?

[Salmo]

Yes we do get early blight. It is also known as target spot, because the brown spots often have a series of dark rings, and halo blight, because the brown spots are often surrounded by a lighter area of green leaf. The brown spots never cross  leaf veins, hence the confusion with magnesium defficiency.

Late blight also often has a light surround. The diagnostic features without a test are that late blight crosses the veins to make large lesions and on damp days a white mould is seen round the edges of the lesion on the back of the leaf.

[Headgardener22]

Hi Salmo,

Then why do the RHS make their statement (in their August Newsletter)? It seems that they are making us feel safer than we really are.

[mumofstig]

Then why do the RHS make their statement (in their August Newsletter)? It seems that they are making us feel safer than we really are.

Why don't you write and ask them 

[arugula]

Hi Salmo,

Then why do the RHS make their statement (in their August Newsletter)?

I take it you refer to this link inthe newsletter:

http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=217&utm_campaign=P3+GYO+Aug+2012+Newsletter+&utm_source=emailCampaign&utm_medium=email&utm_content=

It says that early blight is not common in UK gardens, but doesn't say that it does not exist.

[mumofstig]

This article suggests farmers were beginning to worry about it in 2010
http://www.thescottishfarmer.co.uk/early-blight-gains-greater-significance.9031915

[sunshineband]

Early blight is a lot more prevalent than it used to be.

Salmo is exactly right. It is easy to distinguish from late blight by the halo-like yellowish ring around the brown mark on leaves, and it stays within the sections created by the vein pattern too.

Late blight has no halo, and goes over the vein sections

Preventative spraying against late blight need to start ahead of any attack - it is not a cure. This year late blight arrived on our site at the beginning of July.

Last year is wasn't seen until the end of August.

The RHS can only generalise: it does not give exact dates as these are condition dependent

[Headgardener22]

I accept therefore that early blight is a greater problem than it was (and I will write to the RHS but as I'm not a member I don't expect much response).

Does early blight affect tomatoes?