Blight has struck again!!

[Lara's lottie]

Hi all

Just spotted the first signs of blight on my potatoes (Guildford area), just a few leaves on some of the salad potatoes I had growing in tubs at my house, the one down my allotment seem fine at the moment although my neighbours look like they are coming down. Fingers crossed I have caught it early not sure I could cope with having to chuck all my potatoes and tomatoes out again. I have picked off the infected leaves and given the ones down the lottie a spray with Bordeaux mix and the salad potatoes and tomatoes at my house a spray with Murphy's Cooper Fungicide not sure there is much difference between the two but the Murphy's one came in a sachet which was easier to use as I only needed a smaller amount for the house.

It was my Anya salads (second early) that came down first, no sign on the Charlottes (second Early - salad) I have at the house, down the lottie I have Mayan Gold (not quite worked out what these are I think early maincrop type), Yukon Gold (second Early - baker), King Edwards (early maincrop - Roaster) and Cara (late maincrop- Baker). The earlies should hopefully be ready to lift soon, although I was a bit late getting them in as our allotments were pretty waterlogged over the spring. It will be interesting to see the difference in resistance if the blight does spread, as last year I had Belle de fontenay which were pretty much wiped out both leaf and tuber were affected but the King Edwards and Verity (a bit like a Cara type) managed to hang in there and I got a ok crop of half size potatoes. The Mayan Gold surprisingly did really well despite the blight being rampant everywhere.

Am really glad I sowed some of the Legend blight resistant tomatoes, I will keep this updated with how they fare compared to the other varieties I have (Gardeners Delight, Roma, Oxheart, Tigarella).

[growbag]

Havent spotted any here yet- South Wales. This year I have planted Sarpo Axona, Sarpo Mira & Cara as maincrops- fingers crossed. I lost all my tomatoes last year about 17 plants! was gutted.

[Paulottie]

Hi Lara.

I'm near you...It helps if you put location in your profile.

I lost loads of toms and mainly the anya potatoes last year.

You may be right as I've noticed a few blight spots on juliette and int kidney spuds and sprayed with bordeaux mixture last week. mains (king edward, rattes, desiree and PFA) look OK as do the toms but get spraying if I were you.

[Mr Griff]

Thanks for the warning. I live in Rugby & there is no sign yet, but I'll be straight down to the lottie tonight after work to check it out.
Steve G

[Snadger]

Surprised to see Bordeau mixture for sale in the organic gardening catalogue?

It's a mixture of copper sulphate and hydrated lime.

Not having a go at anyone for using it, if it saves your tattie crop and it's passed the pesticde regulations it must be ok............

[Paulottie]

I think it is soil association approved but certainly still available. As it is used in vineyards I don't suppose the EU will ban it! Burgundy mixture is without lime and tends to clog up sprayer less. Certainly a nicer fungicide than Mancozeb. was /is

[Mr Griff]

Hi,
Checked my tatties last night and i think they are OK (touch wood). However i lifted one lot of Isle of Jura, and the potatos all had lots of white specs on them - it looked like a fungus of some sort. It rubbed off OK and the tatties look fine.
Anyone any ideas?

[Nicos]

Mr Griff.....

White spots are fine- just ignore them

[Lara's lottie]

Yep, I was surprised that Bordeaux mix were ok'd by the Soil Association, although I think the recommend that it is only applied 3 times per season to reduce the accumulation of copper in the soil. So I think as long as the spray is carefully applied and a rotation is maintained, there should be limited problems with accumulation in the soil.

A press release from the soil association last year stated that 30% of Soil Association organic farmers resorted to the use of copper. Two-thirds managed through the use of blight resistant varieties [1], crop rotations [2] and burning or chopping infected vegetation [3].

The Soil Association state that - they only allows the use of copper when disease is a major threat to the crop and hopes to reduce the amount farmers can use as alternative organic controls and resistant strains of potatoes are being developed. And that - Up to four pesticides are permitted (rotenone, soft soap, copper and sulphur) but only as a last resort by the Soil Association; this compares to the 311 chemicals that are available to non-organic farmers. The maintenance of biodiversity to encourage natural predators, crop rotations and preserving optimum crop health are fundamental practices used in organic systems to reduce the incidence of pests and disease.

Link to the press release
Pesticides

As a scientist I am split on the organic movements decisions, I think it is definitely correct to limit the applications of chemicals etc but many of their reasoning is flawed and based on tradition rather than hard science and the GMO issue raises many questions if a species of say potatoes could be genetically modified to be resistant to blight, scab etc etc that would mean there would be no need for the use of chemical to treat these ailments but is GM bad? You could go on for ages listing the arguments of conventional vs. organic, and I think care has to be taken before just blindly accepting the organic movements/soil associations word on the fact that Organic is better. Just as the case is with the use of fungicides is Bordeaux mix ok just because it is traditional or would it be better if you were going to spray for blight prevention to use a newer fungicide?

I try and be as organic as possible on my allotment but gave in this time, and am going to aim to use more resistant varieties, I have Cara this year which has good levels of blight resistance and I was tempted to try the Sarpo varieties of potatoes this year and I think I will definitely give them a try next year has anyone who has grown them got any suggestions on there taste, is the Axona better that the Mira or visa versa, and what they are good for culinary wise?

[SarzWix]

I had to cut down & burn 6 tomato plants and 2 tubs of potatoes yesterday due to blight Another 6 tubs of potatoes have had a lot of leaves picked off and burnt, and the maincrops (Desiree) have had around half of their leaves removed. The toms in the greenhouse seem clean so far.

[moggssue]

My potatoes and tomatoes were all fine on Sunday (in Fulmer, S Bucks) but I'm going to check again tonight, with EVERYTHING crossed. I lost the lot last year, didnt get a single tomato, when I was growing at home so not holding out hopes for the lottie but we'll see ...