Wednesday, 5 August 2009

The B word

It's like mentioning that Scottish play backstage. The 'B' word on the allotments brings fear into the hearts of all.
Two days ago I received an email from the Allotments Association warning of blight on the allotments. Recommending Spraying with Bordeaux mixture. Warning not to compost any of the plants but destroy them.

So let me tell you briefly about blight. It is caused by the fungus Phytophthora infestans. It produces sporangia on infected leaves and fruit which love moisture and riding in the wind for hundreds of miles infecting potatoes and tomatoes alike. You can spray the plants with a copper based fungicide (Bordeaux Mixture) or mancozeb (Dithane) both are nasty chemicals. I checked on a couple of forums about blight yesterday and read that Bordeaux was acceptable by organic standards.

Off I went and got this horrid bottle of blue powder read on the bottle "NOT GOOD FOR THE ENVIRONMENT" - strong words, also they were strong warnings about harming marine life. As I got to the allotments I saw my friends, 'the vegetarians' wheel-barrowing off their tomatoes - some of the first to be noticed with the dreaded blight. They showed me other plots that had it. Pointing out the brown marks on tomatoes etc. They said that mine looked great and no sign of any nasty blight. I was encouraged to 'save' then with the Bordeaux mixture. Regrettably, I very grumpily mixed up the solution and sprayed all my plants. Just to reiterate, I do not have any blight on my tomatoes (yet!)

I was miserable when I left the plots. What have I done? Sprayed some terrible poison on to my plot to save tomatoes that now I'm not sure I want to eat!! What should I have done? Picked all those little tomatoes (most are still small) and made chutney, and composted the plants? My innocent tomatoes are now all blue. And me all blue too.

And to make matters worse when I trawled the web looking for more info on blight last night, I find that bordeaux mixture is not accepted in organic growing and is banned in large scale use. I do not know what or who to believe. I shall fall back on RHS advice I think.

To quote the RHS website:
Tomatoes grown under glass are not always infected. Plants likely to be attacked - especially outdoor tomatoes - require protective sprays of mancozeb (Dithane) or copper (Murphy Traditional Copper or Vitax Bordeaux Mixture). Apply these before the symptoms are seen as a protection against attack. They will not totally prevent infection, but slow it sufficiently to save crop.


Carrie said...

Fear not Tash, we use Bordeaux mixture when we have to especially on roses. On food we would go there if pushed, it's the lesser of 2 evils. Just use it sparingly and don't feel guilty.

Kella said...

I can safely say I would be one those to lose my toms as I don't think I could eat my veg after knowingly spraying it, I might as well buy my veg. So I know exactly how you feel.

I lost all my tomato laden plants in the wet summer of 2007 and didn't want to experience that horrible feeling again so last year I tried building a cover over my outside tomatoes. And though I did get blight, when it finally arrived I was able to keep it in check and I finally removed the plants after the second frost and not because of blight. Here is a link where I explain what I did and the outcomes from last year (I'm thifasmom).

Maybe you could try something similar next year or even this year if you have the space to fit in a similar structure into the growing space.

I wish you a great tomato crop, wash them well and don't lose heart, we all have to compromise our principles at one time or another on the road of life.

Matron said...

I have always understood that Bordeaux mixture is accepted by organic gardeners, though I've never looked it up. I suffered badly with blight last year, if you do a word search on my blog you will see the awful pictures. If your potatoes are maincrop, then dig up one of the plants and see how they are growing. If they are an acceptable size, then completely cut the green tops off and get rid of them. Cut your losses and have a smaller crop of potatoes. This year I am growing a blight resistant potato Sarpo Axona just in case.

Jo said...

We have no sign of blight on our site at the moment, but with this mix of weather we're having it can't be too far away.
I think I would have just cut my losses and picked the fruit you have already, and try again next year.