[Benandbill]

What are the symptoms?  Some of the stems of my plants are going  darker and some of the fruits' skin is going from smooth green do a slightly rougher surfaced brown colour.

If it is blight, is there any way it can be treated, and for the future, any preventative measure that can be recommended?

[DD.]

Sounds like blight.

For future, have a look at this in the FAQ section.

http://chat.allotment-garden.org/index.php?topic=56717.0

[JayG]

Last year I was panicked into ripening all my Red Alert outdoor toms indoors because some of the stems showed signs of a spreading dark colouration and I couldn't really decide whether various imperfections on the leaves were blight infections or just normal wear and tear.

In actual fact the plants continued to live quite normally and is probably just a feature of this (and possibly other?) varieties (they are exactly the same this year.)

Check out all tomato blight pictures you can find and if you are sure it is blight, act quickly, remove all the fruit, destroy the plants, and try and ripen them indoors. Don't try and ripen the suspect fruits, and keep a close watch on the others as they may not be showing the infection yet.

[Benandbill]

Thanks all for your responses.  JayG, much the same as you, I can't be sure if it's just wear and tear.  I wasn't prepared for them to grow so big, only used half sized canes and haven't bothered tying them so they're a right mess now.  Also. they've been exposed to all weathers as I don't have a greenhouse, so I'm hoping it's something less sinister.

My better half's been thumbing through an old book and it says in there they'll sometimes stay green if there's no magnesium in the feed.  We checked the feed and lo and behold, there's no magnesium, so that could be part of our problem.

There were other tips lie not growing them too close together.  Well I don't know about you but I've got 3 plants to a grow bag and with my ring culture plastic pots, they just about fit in.  Maybe next year, I'll feed them more magnesium, grow 2 plants to a bag and tie them up on proper supports.  Even better would be to get a decent greenhouse, but I only have half a plot at the mo so that would limit growing space too much.

[JayG]

Good plan!

Even though growbags are often invitingly marked with 3 cutouts I think three tomato plants per bag is too many, especially for bush types, and the overcrowding will tend to create a microclimate perfect for blight spore germination.

I would have though all purpose-bought tomato fertilisers contained magnesium, but from what you say it's obviously worth checking to make sure.