Topic: This is why blight struck even before a humidity reached 'smith period' levels.

[Vinlander]

It's obvious from the recent blight posts that lots of people know this, and it's kind of obvious, but I think it's worth spelling out for beginners.

Blight spores don't check the humidity online !!!

In other words it's the local humidity inside your tomato patch that matters not the humidity at the nearest weather station.

Everyone who works the soil will have noticed how much more muggy it gets if you work behind a windbreak or among tall plants planted close together.

Plants produce moisture when they try to cool themselves, and if the air can't move through then the humidity will shoot way up above the monitoring station on a rooftop like the one on the Met Office.

It's asking for trouble if you plant tomatoes in blocks instead of wide rows that are oriented to let the prevailing wind through.

It's asking for trouble if you don't remove all the side-shoots (axils) - so the plants join up to make a windbreak.

This means bush types need to be further apart despite being generally shorter plants.

If you are growing big varieties (which have big flat surfaces to catch and hold rain) then it's worth putting a cover over individual fruits.

Cheers.

[Jeannine]

Hi, I just got home from our plots and spoke to a man who has been spraying copper spray on his tomatoes  and potatoes regularly since late May,he was very shocked to discover blight on his plants he has  pulled the lot out.

So far I am still OK..but although isolated and covered  but  I am even more worried now.

Oh the waiting game..

XX Jeannine

[plainleaf]

spraying copper spray on tomatoes is not always effective on blight. something stronger chemical are needed. Also pruning has been shown to cause tomatoes to be more likely to be damaged by disease vectors.

[sunloving]

Its all very well stating that toms should be separate and in wide apart rows but actually not many of us have massive gardens or growing space on an industrial scale and it is a trade of between yeild per meter and the timing of blight.

I have a 15ft greenhouse that has 30 plants in, each one gives me any pounds of toms with or without blght each year its just a question of thier colour. I could grow just 10 plants instead and would have fewer tomatoes and still be at risk of blight every year as they are in the greenhouse.
So its a question of common sense.
Id rather have buckets of fresh tomatoes and deal with blight than have a tiny yeild.
X sunloving

[antipodes]

This is true, also you don't always know how your tomatoes will grow. Every year I space wider apart but I still end up with the plants touching one another. The bush types do seem more disease prone, but I guess that is because they are bushy! 
I have been removing any yellowing or spotted leaves and so far everything seems OK. I am starting to get a few tomatoes every day and the very big vines with the beefsteak types seem in very good condition.

[Ellen K]

What happens on our site is that one plotholder gets the blight (on a dense patch of tomato plants which he waters every day with a sprinkler - he does this every year), does nothing about it then we all get it regardless of how we are growing.

Another poster has said the same thing (it might have been Sunloving but I can't find the post).

So while spacing and careful watering is great, it only works if everyone on the site is doing it.  Because when the spore load is very heavy from a nearby infected crop, you are trying to hold back the tide with a teaspoon.

The funny thing is that we still grow them, in spite of the odds.  Gardeners, eh?

[Vinlander]

It's true that in really bad years like 2008 and 2009 nothing is much good - if it's so bad that good 'air management' backed by copper doesn't work then I'd rather use nothing than risk my future health (10 or 20 years hence) by using dithane or other even newer,  less tested and ever more complex molecules with unpredictably toxic novelty effects (the joke is always on you).

Instead I act on the same thinking DenbyVisitor refers to - I rely on my 2 substitutes - which are dead easy to grow and entirely immune to blight:

The annual physalis or 'ground cherry' is yellow and a bit more like a fruit than tomatoes are, but they are fine in mixed salad - you can always increase the bitter stuff to compensate - extra chicory, raw courgette etc.

The 'lychee tomato' is pretty much half way between tomatoes and the ground cherry above - a closer taste though it is seedier than either (and incredibly thorny). I think they actually taste a lot better than blight resistant tomato varieties (which don't work in a bad year anyway). They are savoury enough to work well in sauces.

It really is a workable option.

Cheers.