Topic: Bordeaux mixture, Dithane safe to eat tomatoes?

[dingerbell]

I lost all my outdoor toms last year to blight. I'm going to try once more. My toms are all looking good at the moment but I am planning to use a spray to protect them. Is it safe to eat toms after treatment? Which is more effective, Dithane or Bordeaux mixture? Stand back, here come the experts... ;D

[saddad]

I wouldn't use either, but keep an eye on the blight forecast and take them off and use green as chutney, or hang up the whole plant to ripen on the vine in a greenhouse, polytunnels tend to be to damp...
 ???

[Robert_Brenchley]

If they get blight, chutney the lot, or at least as many as you can. That way at least you save something. I'm keeping my fingers crossed.

[sandersj89]

Hmmm, this could open a can of worms.

I have used both in the past, Bordeaux does have "organic" approval but even the Soil Association seem to be a bit embarrassed about that as it is based around Copper.

Interesting piece here but a couple of years old:

http://news.bbc.co.uk/1/hi/northern_ireland/3004382.stm

Dithane is a commercial application and in my view works better.

But, and it is a big but, neither is a cure and they are only preventative. Most instructions say spray every two weeks but it it rains any time you need to respray, even if it is only 24 hours later.

Last year I had some success with a "Blight Resistant" variety of tomato, Ferline. These is another called Legend. This did finally succumb but not until October.

I have not tried the Sarpo family of potatoes yet as I have heard mixed reports about their taste.

HTH

Jerry

[Robert_Brenchley]

I think the reality is that if it's commercially expedient to use something, and it's been around for long enough, then a chemical will get 'organic' approval. Personally I don't care how long Bordeaux mixture has been in use, I'm not using it.

[growmore]

Think You are right Jerry ..Can of worms....  :)

I look at it this way I will use  a spray when I know of no alternative remedy. I think the stuff available to us as gardeners is pretty safe  compared to what commercial growers are allowed to use ..
If I couldn't grow it ..I would have to buy their veg which I feel sure has had a lot more chemicals than mine sprayed at it.
Just read bottle as to time between spraying and harvesting and  adhere to strength of mixture they reccomend..  Jim..

[Hector]

So you can prevent with Dithane? Packet says wait till signs of blight. Not questioning, just confused :)

[amphibian]

So you can prevent with Dithane? Packet says wait till signs of blight. Not questioning, just confused :)

Does it mean signs of blight in your locality, rather than on your actual plants.

I have used Bordeaux to good effect in the past, but am determined not to use it any more.

It's hard to resist though, and if I don't use it my crop may fail, if it fails I will have to buy potatoes/tomatoes, which even if 'organic' are bound to have been sprayed with Bordeaux anyway.

The brutal reality is it is very hard to grow blight sensitive crops with any regularity, in the UK, without resorting to Bordeaux.


Blight was not bad, here, last year. I'm hoping we escape it again this year, but tehre is quite a large outbreak in potatoes in Margate already.

[OllieC]

Bordeaux - because you can tell if it's all been washed off when you are eating them!

[tim]

Dinger - growers use Dithane - & there is no need to spray the fruit itself??

[Kepouros]

Neither Bordeau Mixture nor Dithane have any systemic properties whatever, which is why they cease to give any protection once they have been washed off the plant by rain, and neither is known to leaves residues in the crop.

All that should be necessary is to wash your tomatoes before eating them.  Why else do you think that virtually every carton of soft fruit, from peaches to tomatoes to grapes, carries the injunction "Wash before Use"?

[tim]

Nice point but, as I said, no need to cover the fruit. It's the leaves that pick up the disease?

Please tell me if I'm up the creek there, Kepouros.

[OllieC]

Once Bordeaux has dried, it doesn't wash off all that easily - you need to rub whilst rinsing. No residue IN the crop, but plenty ON it!

re: Tim's point - I can't quite visualise how to miss the fruit... I coat everything... would welcome any spraying tips!

[tim]

1. Yes - if you're lucky!

2. If you wish to cover the fruit, fine. I have more time than most &, since there are usually more leaves than fruit -
[attachment=1] - I adjust the jet & pressure to mostly hit the leaves.

Fair??

[tim]

I'm biding my wee about the leaf/fruit idea - I have expert advice coming in.

[amphibian]

When spraying you can use a piece of cardboard to shield the fruit from direct spray.

[Kepouros]

tim, I`m afraid that you`re being a little bit optimistic.  Tomato blight spores will infect any tomato tissue on which they land, and any which land on the fruit can (and probably will) infect the fruit, and rot develops at the infected sites and quickly consumes the whole fruit.  Furthermore, in certain conditions of alternating dryness and wetness there is a two way transference of moisture between the fruit and the rest of the plant, so a blight spore landing on an untreated fruit could infect the whole of an otherwise protected plant.

[Kepouros]

Sorry, I accidentally clicked the `send` button too soon.

Perhaps I could clear up one or two misunderstandings which I noted in foregoing posts.

First, only the Soil Association and HDRA make any pretence whatever that Bordeau Mixture is organic, and they have to do so or so-called organic production of potatoes in the British Isles would cease as there is no actual organic remedy for blight.  At present a maximum of 3 sprays of Bordeau is permitted per crop by the Soil Association and it is anybody`s guess how many `organic` growers observe this, and how many use copper oxychloride instead.

Second, neither Dithane nor Bordeau Mixture is fully preventative, but both give limited protection, which lasts only so long as there is a complete film of residue on all the plant tissues.  If that film is interrupted a blight spore can attack.  The problem is that even where there is no rain to wash away the film the upper plant leaves are growing every day, and stretching, thinning and breaking that film.

In answer to Hector, the instruction to wait for signs of blight means signs in your immediate vicinity.  If you wait until you see signs in your own plants you`ve missed the `bus.

As to whether to use either spray, amphibian has hit the nail on the head.  If your own crop fails for whatever reason you`ll end up buying fruit (even `organic` fruit) which will have been treated with bordeau mixture, or something worse. If you buy fruit from abroad heaven knows what you`ll get.

If you do getblight on your plants, then the same action that I keep reccomending in respect of blight on potatoes will work to slow down drastically the spread in tomato plants, as I`m sure tim will agree.

[tim]

Thanks, Kepourus - I stand corrected. At least it got us to the truth!

In fact, I don't spray against Blight, but I do spray such things as SM3 which I have to keep off the fruit - or Wife says fish! -

[small]

I hope this an appropriate thread to ask a side question. In 30 years I've had blight on potatoes once, and on tomatoes, never: I'm in an isolated garden, not an allotment, could that be why? I've been alarmed by what I have read in this forum and have signed up for notification, I'm prepared to spray if need be: my question really is, are greenhouse toms as badly affected? I've got the best, earliest crop \I've ever had this year and would be desolated to lose them.