Spraying against tomato blight

[Primrose]

I was reading the long term forecast of wet weather for July and August and wonder whether it's too early to start spraying my outdoor tomatoes against blight now as a precaution. They haven't got flowers on them yet but I don't want to lose a couple of dozen carefully nurtured plants. What is everybody else doing?

[Tigger]

I'm just going to whisper this 'cos I don't want to stir up another debate about the 'o' word......

I don't spray anything that we're going to eat, so I'll just take my chance with blight.

[Chantal]

I'm with Tigger, I don't spray. However, I'm trying to plant as many tomatoes as possible in the greenhouses and am trying to dream up some sort of plastic shelter for my tomatoes on the plot.

[Johnboy]

Since when have both of you been eating Tomato foliage? With precautionary spraying you can cover the trusses and target the foliage.
The use of plastic can be more of an aid to blight than against it. With plastic you are very likely to cause the humid conditions in which blight occurs.
Good ventilation is very critical when blight is about.
JB.

[Catherine]

This year because we lost all our tomatoes in the polytunnel last year I have planted out almost all my tomatoe plants in the plot in very large pots. Thought I was doing the right thing now I am not so sure. When do you spray for blight and with what. Sorry to sound stupid but I know I can look it up on the net but I find I get more information from you helpful people than having to troll through loads of inforamtion that isn't relevant. Thank you in anticipation.

[Primrose]

Catherine - I don't like using sprays but I dislike losing all my tomatoes to blight even more, so I spray with Dithane. You can buy it from Garden Centres in boxes containing about five sachets of powdered substance. Dissolve each sachet of powder in the recommended amount of water. I then put my dissolved liquid in empty kitchen or bathroom cleaning spray containers and last year started spraying after the first flowers appeared, on inspecting the leaves very carefully for the browning signs of blight. I managed to nick it in the bud and lost two plants out of about 24 but the other survived by spraying once a week (but not in windy conditions or bright sunshine). Early morning of late evening spraying is usually recommended.

[Chantal]

I'd never actually thought of doing that JB and may just give it a go. Should the tomatoes themselves be washed with anything or do they not get blight if the foliage is clean? I lost all my plants in the space of two days last year.

[Johnboy]

Hi Chantal,
Blight generally starts with the leaves and we are talking prevention here. You would be using the spray with a prayer to ward off the blight.
So if you cover the crop so to speak and spray the leaves only I feel you are getting the job done without compromising yourself.
I lost my outside Tomatoes within a morning last year. The first time that I have ever had blight
on Tomatoes. Those in the tunnel and greenhouse were fine but the outdoor ones had only been planted out just over a week. They were fine in the morning and dead or beyond redemption by late afternoon! Boo Hoo!
JB.

[Chantal]

Thanks JB, I'll have a think about this. I did buy some Bordeaux Mix last year but didn't have the courage to use it as I was worried about spraying fruit I was planning to eat. The result of this was not having any fruit to eat!

I would guess if I put the stuff in a small hand sprayer I'll have good control over what I'm doing and can be very careful.

I'll let you know how I get on as a potential pragmatist.

[Catherine]

I went up to check my allotment last night and found one of the tomatoe plant I had put out side on Tuesday has curled leaved. No marks on the leaves but they are curled. None of the others have just this one Is this something serious?

[Johnboy]

Hi Chantal,
It's called twixt a rock and a hard place!
Pragmatism has an awful lot going for it especially pragmatic growing. Finding a way round of not using chemicals in critical places without even doing a Tigger and whispering the o word.
I really do not see that people should lovingly tend their crops all year and end up with very inferior results that will not store for more than a fortnight at most. If you have insufficient compost or manure then use a man made substance as the odd handful of National Growmore will not do them or the environment the slightest bit of harm. This can make a world of difference.
The New Advanced Slug Pellets carry Organic accreditation so when you hear "the slugs ate all my crops" it now rings somewhat hollow.
Pragmatism is really just plain common sense and thinking for yourself no more no less. This makes growing a real pleasure without turning it into a religion.
JB.

[Geoff]

There is quite a pragmatic article in yesterday's Telegraph - like his opinion on heritage varieties ("The reason many old varieties died out is that people stopped growing them because others were better") and organic ("But then society seems to have lost its trust in science - the rush to the organic section of the supermarket illustrates that many of us are in denial about the realities of feeding the world's 6.6 billion people. The fact is, modern scientific plant-breeding and chemical fertilisers are what protect us from starvation. ...but then logic has never been part of the organic philosophy")
How many do you feed from your plot? What area of land would it take to feed the UK at that productivity?
Apologies that the long link makes it a wide posting.
http://www.telegraph.co.uk/gardening/ma ... ury106.xml

[Chantal]

Next question JB, is Bordeaux Mix systemic or does it just coat the leaves and stem?

[Johnboy]

Hi Chantal,
I believe Bordeaux Mixture to be non-systemic although when used on Potatoes the Copper content can be taken up by the roots when washed in by rain so from that I suppose technically it could be taken up by the Tomato roots.
The point is though that you will be mist spraying your plants and how much of that spray will even reach the ground, although debatable, will be minuscule. There are more modern treatments for blight that treat only the leaves and can in no way affect the crop. Sadly the more modern up to date treatments do not carry Organic Accreditation so in this instance, for example, Organic Potatoes are free to take up copper and this makes non organic Potatoes by far the safer option and they are certainly cheaper to buy when your own supply runs out.
To be pragmatic when spraying your tomatoes cover the ground around the plant with polythene to catch any immediate run-off if you are that much concerned.
Probably if you had a full soil analysis of your plot you would find Copper listed in the full spectrum of chemicals therein. Strangely so would Arsenic which quite alarms some people.
JB.